diff --git a/core/src/main/java/org/apache/calcite/rel/rules/SubQueryRemoveRule.java b/core/src/main/java/org/apache/calcite/rel/rules/SubQueryRemoveRule.java
index 1a8add9..e63999d 100644
--- a/core/src/main/java/org/apache/calcite/rel/rules/SubQueryRemoveRule.java
+++ b/core/src/main/java/org/apache/calcite/rel/rules/SubQueryRemoveRule.java
@@ -157,105 +157,235 @@
     //   from emp) as q
     //
     final SqlQuantifyOperator op = (SqlQuantifyOperator) e.op;
+    switch (op.comparisonKind) {
+    case GREATER_THAN_OR_EQUAL:
+    case LESS_THAN_OR_EQUAL:
+    case LESS_THAN:
+    case GREATER_THAN:
+    case NOT_EQUALS:
+      break;
 
-    // SOME_EQ & SOME_NE should have been rewritten into IN/ NOT IN
-    assert op == SqlStdOperatorTable.SOME_GE || op == SqlStdOperatorTable.SOME_LE
-        || op == SqlStdOperatorTable.SOME_LT || op == SqlStdOperatorTable.SOME_GT;
+    default:
+      // "SOME =" should have been rewritten into IN.
+      throw new AssertionError("unexpected " + op);
+    }
 
     final RexNode caseRexNode;
     final RexNode literalFalse = builder.literal(false);
     final RexNode literalTrue = builder.literal(true);
     final RexLiteral literalUnknown =
         builder.getRexBuilder().makeNullLiteral(literalFalse.getType());
+
     final SqlAggFunction minMax = op.comparisonKind == SqlKind.GREATER_THAN
         || op.comparisonKind == SqlKind.GREATER_THAN_OR_EQUAL
         ? SqlStdOperatorTable.MIN
         : SqlStdOperatorTable.MAX;
 
     if (variablesSet.isEmpty()) {
-      // for non-correlated case queries such as
-      // select e.deptno, e.deptno < some (select deptno from emp) as v
-      // from emp as e
-      //
-      // becomes
-      //
-      // select e.deptno,
-      //   case
-      //   when q.c = 0 then false // sub-query is empty
-      //   when (e.deptno < q.m) is true then true
-      //   when q.c > q.d then unknown // sub-query has at least one null
-      //   else e.deptno < q.m
-      //   end as v
-      // from emp as e
-      // cross join (
-      //   select max(deptno) as m, count(*) as c, count(deptno) as d
-      //   from emp) as q
-      builder.push(e.rel)
-          .aggregate(builder.groupKey(),
-              builder.aggregateCall(minMax, builder.field(0)).as("m"),
-              builder.count(false, "c"),
-              builder.count(false, "d", builder.field(0)))
-          .as("q")
-          .join(JoinRelType.INNER);
-      caseRexNode = builder.call(SqlStdOperatorTable.CASE,
-          builder.equals(builder.field("q", "c"), builder.literal(0)),
-          literalFalse,
-          builder.call(SqlStdOperatorTable.IS_TRUE,
-              builder.call(RexUtil.op(op.comparisonKind),
-                  e.operands.get(0), builder.field("q", "m"))),
-          literalTrue,
-          builder.greaterThan(builder.field("q", "c"),
-              builder.field("q", "d")),
-          literalUnknown,
-          builder.call(RexUtil.op(op.comparisonKind),
-              e.operands.get(0), builder.field("q", "m")));
-    } else {
-      // for correlated case queries such as
-      //
-      // select e.deptno, e.deptno < some (
-      //   select deptno from emp where emp.name = e.name) as v
-      // from emp as e
-      //
-      // becomes
-      //
-      // select e.deptno,
-      //   case
-      //   when indicator is null then false // sub-query is empty for corresponding corr value
-      //   when q.c = 0 then false // sub-query is empty
-      //   when (e.deptno < q.m) is true then true
-      //   when q.c > q.d then unknown // sub-query has at least one null
-      //   else e.deptno < q.m
-      //   end as v
-      // from emp as e
-      // left outer join (
-      //   select name, max(deptno) as m, count(*) as c, count(deptno) as d,
-      //       "alwaysTrue" as indicator
-      //   from emp group by name) as q on e.name = q.name
-      builder.push(e.rel)
-          .aggregate(builder.groupKey(),
-              builder.aggregateCall(minMax, builder.field(0)).as("m"),
-              builder.count(false, "c"),
-              builder.count(false, "d", builder.field(0)));
+      switch (op.comparisonKind) {
+      case GREATER_THAN_OR_EQUAL:
+      case LESS_THAN_OR_EQUAL:
+      case LESS_THAN:
+      case GREATER_THAN:
+        // for non-correlated case queries such as
+        // select e.deptno, e.deptno < some (select deptno from emp) as v
+        // from emp as e
+        //
+        // becomes
+        //
+        // select e.deptno,
+        //   case
+        //   when q.c = 0 then false // sub-query is empty
+        //   when (e.deptno < q.m) is true then true
+        //   when q.c > q.d then unknown // sub-query has at least one null
+        //   else e.deptno < q.m
+        //   end as v
+        // from emp as e
+        // cross join (
+        //   select max(deptno) as m, count(*) as c, count(deptno) as d
+        //   from emp) as q
+        builder.push(e.rel)
+            .aggregate(builder.groupKey(),
+                builder.aggregateCall(minMax, builder.field(0)).as("m"),
+                builder.count(false, "c"),
+                builder.count(false, "d", builder.field(0)))
+            .as("q")
+            .join(JoinRelType.INNER);
+        caseRexNode = builder.call(SqlStdOperatorTable.CASE,
+            builder.equals(builder.field("q", "c"), builder.literal(0)),
+            literalFalse,
+            builder.call(SqlStdOperatorTable.IS_TRUE,
+                builder.call(RexUtil.op(op.comparisonKind),
+                    e.operands.get(0), builder.field("q", "m"))),
+            literalTrue,
+            builder.greaterThan(builder.field("q", "c"),
+                builder.field("q", "d")),
+            literalUnknown,
+            builder.call(RexUtil.op(op.comparisonKind),
+                e.operands.get(0), builder.field("q", "m")));
+        break;
 
-      final List<RexNode> parentQueryFields = new ArrayList<>(builder.fields());
-      String indicator = "trueLiteral";
-      parentQueryFields.add(builder.alias(literalTrue, indicator));
-      builder.project(parentQueryFields).as("q");
-      builder.join(JoinRelType.LEFT, literalTrue, variablesSet);
-      caseRexNode = builder.call(SqlStdOperatorTable.CASE,
-          builder.isNull(builder.field("q", indicator)),
-          literalFalse,
-          builder.equals(builder.field("q", "c"), builder.literal(0)),
-          literalFalse,
-          builder.call(SqlStdOperatorTable.IS_TRUE,
-              builder.call(RexUtil.op(op.comparisonKind),
-                  e.operands.get(0), builder.field("q", "m"))),
-          literalTrue,
-          builder.greaterThan(builder.field("q", "c"),
-              builder.field("q", "d")),
-          literalUnknown,
-          builder.call(RexUtil.op(op.comparisonKind),
-              e.operands.get(0), builder.field("q", "m")));
+      case NOT_EQUALS:
+        // for non-correlated case queries such as
+        // select e.deptno, e.deptno <> some (select deptno from emp) as v
+        // from emp as e
+        //
+        // becomes
+        //
+        // select e.deptno,
+        //   case
+        //   when q.c = 0 then false // sub-query is empty
+        //   when e.deptno is null then unknown
+        //   when q.c <> q.d && q.d <= 1 then e.deptno != m || unknown
+        //   when q.d = 1
+        //     then e.deptno != m // sub-query has the distinct result
+        //   else true
+        //   end as v
+        // from emp as e
+        // cross join (
+        //   select count(*) as c, count(deptno) as d, max(deptno) as m
+        //   from (select distinct deptno from emp)) as q
+        builder.push(e.rel);
+        builder.distinct()
+            .aggregate(builder.groupKey(),
+                builder.count(false, "c"),
+                builder.count(false, "d", builder.field(0)),
+                builder.max(builder.field(0)).as("m"))
+            .as("q")
+            .join(JoinRelType.INNER);
+        caseRexNode = builder.call(SqlStdOperatorTable.CASE,
+            builder.equals(builder.field("c"), builder.literal(0)),
+            literalFalse,
+            builder.isNull(e.getOperands().get(0)),
+            literalUnknown,
+            builder.and(
+                builder.notEquals(builder.field("d"), builder.field("c")),
+                builder.lessThanOrEqual(builder.field("d"),
+                    builder.literal(1))),
+            builder.or(
+                builder.notEquals(e.operands.get(0), builder.field("q", "m")),
+                literalUnknown),
+            builder.equals(builder.field("d"), builder.literal(1)),
+            builder.notEquals(e.operands.get(0), builder.field("q", "m")),
+            literalTrue);
+        break;
+
+      default:
+        throw new AssertionError("not possible - per above check");
+      }
+    } else {
+      final String indicator = "trueLiteral";
+      final List<RexNode> parentQueryFields = new ArrayList<>();
+      switch (op.comparisonKind) {
+      case GREATER_THAN_OR_EQUAL:
+      case LESS_THAN_OR_EQUAL:
+      case LESS_THAN:
+      case GREATER_THAN:
+        // for correlated case queries such as
+        //
+        // select e.deptno, e.deptno < some (
+        //   select deptno from emp where emp.name = e.name) as v
+        // from emp as e
+        //
+        // becomes
+        //
+        // select e.deptno,
+        //   case
+        //   when indicator is null then false // sub-query is empty for corresponding corr value
+        //   when q.c = 0 then false // sub-query is empty
+        //   when (e.deptno < q.m) is true then true
+        //   when q.c > q.d then unknown // sub-query has at least one null
+        //   else e.deptno < q.m
+        //   end as v
+        // from emp as e
+        // left outer join (
+        //   select name, max(deptno) as m, count(*) as c, count(deptno) as d,
+        //       "alwaysTrue" as indicator
+        //   from emp group by name) as q on e.name = q.name
+        builder.push(e.rel)
+            .aggregate(builder.groupKey(),
+                builder.aggregateCall(minMax, builder.field(0)).as("m"),
+                builder.count(false, "c"),
+                builder.count(false, "d", builder.field(0)));
+
+        parentQueryFields.addAll(builder.fields());
+        parentQueryFields.add(builder.alias(literalTrue, indicator));
+        builder.project(parentQueryFields).as("q");
+        builder.join(JoinRelType.LEFT, literalTrue, variablesSet);
+        caseRexNode = builder.call(SqlStdOperatorTable.CASE,
+            builder.isNull(builder.field("q", indicator)),
+            literalFalse,
+            builder.equals(builder.field("q", "c"), builder.literal(0)),
+            literalFalse,
+            builder.call(SqlStdOperatorTable.IS_TRUE,
+                builder.call(RexUtil.op(op.comparisonKind),
+                    e.operands.get(0), builder.field("q", "m"))),
+            literalTrue,
+            builder.greaterThan(builder.field("q", "c"),
+                builder.field("q", "d")),
+            literalUnknown,
+            builder.call(RexUtil.op(op.comparisonKind),
+                e.operands.get(0), builder.field("q", "m")));
+        break;
+
+      case NOT_EQUALS:
+        // for correlated case queries such as
+        //
+        // select e.deptno, e.deptno <> some (
+        //   select deptno from emp where emp.name = e.name) as v
+        // from emp as e
+        //
+        // becomes
+        //
+        // select e.deptno,
+        //   case
+        //   when indicator is null
+        //     then false // sub-query is empty for corresponding corr value
+        //   when q.c = 0 then false // sub-query is empty
+        //   when e.deptno is null then unknown
+        //   when q.c <> q.d && q.d <= 1
+        //     then e.deptno != m || unknown
+        //   when q.d = 1
+        //     then e.deptno != m // sub-query has the distinct result
+        //   else true
+        //   end as v
+        // from emp as e
+        // left outer join (
+        //   select name, count(distinct *) as c, count(distinct deptno) as d,
+        //       max(deptno) as m, "alwaysTrue" as indicator
+        //   from emp group by name) as q on e.name = q.name
+        builder.push(e.rel)
+            .aggregate(builder.groupKey(),
+                builder.count(true, "c"),
+                builder.count(true, "d", builder.field(0)),
+                builder.max(builder.field(0)).as("m"));
+
+        parentQueryFields.addAll(builder.fields());
+        parentQueryFields.add(builder.alias(literalTrue, indicator));
+        builder.project(parentQueryFields).as("q"); // TODO use projectPlus
+        builder.join(JoinRelType.LEFT, literalTrue, variablesSet);
+        caseRexNode = builder.call(SqlStdOperatorTable.CASE,
+            builder.isNull(builder.field("q", indicator)),
+            literalFalse,
+            builder.equals(builder.field("c"), builder.literal(0)),
+            literalFalse,
+            builder.isNull(e.getOperands().get(0)),
+            literalUnknown,
+            builder.and(
+                builder.notEquals(builder.field("d"), builder.field("c")),
+                builder.lessThanOrEqual(builder.field("d"),
+                    builder.literal(1))),
+            builder.or(
+                builder.notEquals(e.operands.get(0), builder.field("q", "m")),
+                literalUnknown),
+            builder.equals(builder.field("d"), builder.literal(1)),
+            builder.notEquals(e.operands.get(0), builder.field("q", "m")),
+            literalTrue);
+        break;
+
+      default:
+        throw new AssertionError("not possible - per above check");
+      }
     }
 
     // CASE statement above is created with nullable boolean type, but it might
diff --git a/core/src/test/java/org/apache/calcite/test/RelOptRulesTest.java b/core/src/test/java/org/apache/calcite/test/RelOptRulesTest.java
index f54bbf9..c86ccd9 100644
--- a/core/src/test/java/org/apache/calcite/test/RelOptRulesTest.java
+++ b/core/src/test/java/org/apache/calcite/test/RelOptRulesTest.java
@@ -5548,6 +5548,12 @@
     checkSubQuery(sql).withLateDecorrelation(true).check();
   }
 
+  @Test void testSomeWithNotEquality() {
+    final String sql = "select * from emp e1\n"
+        + "  where e1.deptno <> SOME (select deptno from dept)";
+    checkSubQuery(sql).withLateDecorrelation(true).check();
+  }
+
   /** Test case for
    * <a href="https://issues.apache.org/jira/browse/CALCITE-1546">[CALCITE-1546]
    * Sub-queries connected by OR</a>. */
diff --git a/core/src/test/java/org/apache/calcite/test/SqlToRelConverterTest.java b/core/src/test/java/org/apache/calcite/test/SqlToRelConverterTest.java
index 5fee9f3..5a1392d 100644
--- a/core/src/test/java/org/apache/calcite/test/SqlToRelConverterTest.java
+++ b/core/src/test/java/org/apache/calcite/test/SqlToRelConverterTest.java
@@ -1697,6 +1697,12 @@
     sql(sql).expand(false).ok();
   }
 
+  @Test void testSomeWithNotEquality() {
+    final String sql = "select empno from emp where deptno <> some (\n"
+        + "  select deptno from dept)";
+    sql(sql).expand(false).ok();
+  }
+
   @Test void testNotInUncorrelatedSubQueryRex() {
     final String sql = "select empno from emp where deptno not in"
         + " (select deptno from dept)";
diff --git a/core/src/test/resources/org/apache/calcite/test/RelOptRulesTest.xml b/core/src/test/resources/org/apache/calcite/test/RelOptRulesTest.xml
index a99fa46..987802e 100644
--- a/core/src/test/resources/org/apache/calcite/test/RelOptRulesTest.xml
+++ b/core/src/test/resources/org/apache/calcite/test/RelOptRulesTest.xml
@@ -11542,6 +11542,48 @@
 ]]>
     </Resource>
   </TestCase>
+  <TestCase name="testSomeWithNotEquality">
+    <Resource name="sql">
+      <![CDATA[select * from emp e1
+  where e1.deptno <> SOME (select deptno from dept)]]>
+    </Resource>
+    <Resource name="planBefore">
+      <![CDATA[
+LogicalProject(EMPNO=[$0], ENAME=[$1], JOB=[$2], MGR=[$3], HIREDATE=[$4], SAL=[$5], COMM=[$6], DEPTNO=[$7], SLACKER=[$8])
+  LogicalFilter(condition=[<> SOME($7, {
+LogicalProject(DEPTNO=[$0])
+  LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
+})])
+    LogicalTableScan(table=[[CATALOG, SALES, EMP]])
+]]>
+    </Resource>
+    <Resource name="planMid">
+      <![CDATA[
+LogicalProject(EMPNO=[$0], ENAME=[$1], JOB=[$2], MGR=[$3], HIREDATE=[$4], SAL=[$5], COMM=[$6], DEPTNO=[$7], SLACKER=[$8])
+  LogicalProject(EMPNO=[$0], ENAME=[$1], JOB=[$2], MGR=[$3], HIREDATE=[$4], SAL=[$5], COMM=[$6], DEPTNO=[$7], SLACKER=[$8])
+    LogicalFilter(condition=[OR(AND(<>($10, $9), <=($10, 1), OR(<>($7, $11), null), <>($9, 0)), AND(=($10, 1), <>($7, $11), <>($9, 0), OR(=($10, $9), >($10, 1))), AND(<>($9, 0), OR(=($10, $9), >($10, 1)), <>($10, 1)))])
+      LogicalJoin(condition=[true], joinType=[inner])
+        LogicalTableScan(table=[[CATALOG, SALES, EMP]])
+        LogicalProject(c=[$0], d=[$0], m=[$1])
+          LogicalAggregate(group=[{}], c=[COUNT()], m=[MAX($0)])
+            LogicalProject(DEPTNO=[$0])
+              LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
+]]>
+    </Resource>
+    <Resource name="planAfter">
+      <![CDATA[
+LogicalProject(EMPNO=[$0], ENAME=[$1], JOB=[$2], MGR=[$3], HIREDATE=[$4], SAL=[$5], COMM=[$6], DEPTNO=[$7], SLACKER=[$8])
+  LogicalProject(EMPNO=[$0], ENAME=[$1], JOB=[$2], MGR=[$3], HIREDATE=[$4], SAL=[$5], COMM=[$6], DEPTNO=[$7], SLACKER=[$8])
+    LogicalFilter(condition=[OR(AND(<>($10, $9), <=($10, 1), OR(<>($7, $11), null), <>($9, 0)), AND(=($10, 1), <>($7, $11), <>($9, 0), OR(=($10, $9), >($10, 1))), AND(<>($9, 0), OR(=($10, $9), >($10, 1)), <>($10, 1)))])
+      LogicalJoin(condition=[true], joinType=[inner])
+        LogicalTableScan(table=[[CATALOG, SALES, EMP]])
+        LogicalProject(c=[$0], d=[$0], m=[$1])
+          LogicalAggregate(group=[{}], c=[COUNT()], m=[MAX($0)])
+            LogicalProject(DEPTNO=[$0])
+              LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
+]]>
+    </Resource>
+  </TestCase>
   <TestCase name="testSortJoinCopyInnerJoinOrderBy">
     <Resource name="sql">
       <![CDATA[select * from sales.emp join sales.dept on
diff --git a/core/src/test/resources/org/apache/calcite/test/SqlToRelConverterTest.xml b/core/src/test/resources/org/apache/calcite/test/SqlToRelConverterTest.xml
index 39b92d2..3bd6541 100644
--- a/core/src/test/resources/org/apache/calcite/test/SqlToRelConverterTest.xml
+++ b/core/src/test/resources/org/apache/calcite/test/SqlToRelConverterTest.xml
@@ -5912,6 +5912,22 @@
 ]]>
     </Resource>
   </TestCase>
+  <TestCase name="testSomeWithNotEquality">
+    <Resource name="sql">
+      <![CDATA[select empno from emp where deptno <> some (
+  select deptno from dept)]]>
+    </Resource>
+    <Resource name="plan">
+      <![CDATA[
+LogicalProject(EMPNO=[$0])
+  LogicalFilter(condition=[<> SOME($7, {
+LogicalProject(DEPTNO=[$0])
+  LogicalTableScan(table=[[CATALOG, SALES, DEPT]])
+})])
+    LogicalTableScan(table=[[CATALOG, SALES, EMP]])
+]]>
+    </Resource>
+  </TestCase>
   <TestCase name="testSortInSubQuery">
     <Resource name="sql">
       <![CDATA[select * from (select empno from emp order by empno)]]>
diff --git a/core/src/test/resources/sql/some.iq b/core/src/test/resources/sql/some.iq
index 083256f..e0f14bb 100644
--- a/core/src/test/resources/sql/some.iq
+++ b/core/src/test/resources/sql/some.iq
@@ -178,6 +178,276 @@
 
 !ok
 
+# Some sub-query with not equality.
+# Both sides Not NUll.
+select *
+from "scott".emp
+where empno <> some (values (100), (200));
+
++-------+--------+-----------+------+------------+---------+---------+--------+
+| EMPNO | ENAME  | JOB       | MGR  | HIREDATE   | SAL     | COMM    | DEPTNO |
++-------+--------+-----------+------+------------+---------+---------+--------+
+|  7369 | SMITH  | CLERK     | 7902 | 1980-12-17 |  800.00 |         |     20 |
+|  7499 | ALLEN  | SALESMAN  | 7698 | 1981-02-20 | 1600.00 |  300.00 |     30 |
+|  7521 | WARD   | SALESMAN  | 7698 | 1981-02-22 | 1250.00 |  500.00 |     30 |
+|  7566 | JONES  | MANAGER   | 7839 | 1981-02-04 | 2975.00 |         |     20 |
+|  7654 | MARTIN | SALESMAN  | 7698 | 1981-09-28 | 1250.00 | 1400.00 |     30 |
+|  7698 | BLAKE  | MANAGER   | 7839 | 1981-01-05 | 2850.00 |         |     30 |
+|  7782 | CLARK  | MANAGER   | 7839 | 1981-06-09 | 2450.00 |         |     10 |
+|  7788 | SCOTT  | ANALYST   | 7566 | 1987-04-19 | 3000.00 |         |     20 |
+|  7839 | KING   | PRESIDENT |      | 1981-11-17 | 5000.00 |         |     10 |
+|  7844 | TURNER | SALESMAN  | 7698 | 1981-09-08 | 1500.00 |    0.00 |     30 |
+|  7876 | ADAMS  | CLERK     | 7788 | 1987-05-23 | 1100.00 |         |     20 |
+|  7900 | JAMES  | CLERK     | 7698 | 1981-12-03 |  950.00 |         |     30 |
+|  7902 | FORD   | ANALYST   | 7566 | 1981-12-03 | 3000.00 |         |     20 |
+|  7934 | MILLER | CLERK     | 7782 | 1982-01-23 | 1300.00 |         |     10 |
++-------+--------+-----------+------+------------+---------+---------+--------+
+(14 rows)
+
+!ok
+
+# Previous, as scalar sub-query.
+select *, empno <> some (values (100), (200)) as x
+from "scott".emp;
+
++-------+--------+-----------+------+------------+---------+---------+--------+------+
+| EMPNO | ENAME  | JOB       | MGR  | HIREDATE   | SAL     | COMM    | DEPTNO | X    |
++-------+--------+-----------+------+------------+---------+---------+--------+------+
+|  7369 | SMITH  | CLERK     | 7902 | 1980-12-17 |  800.00 |         |     20 | true |
+|  7499 | ALLEN  | SALESMAN  | 7698 | 1981-02-20 | 1600.00 |  300.00 |     30 | true |
+|  7521 | WARD   | SALESMAN  | 7698 | 1981-02-22 | 1250.00 |  500.00 |     30 | true |
+|  7566 | JONES  | MANAGER   | 7839 | 1981-02-04 | 2975.00 |         |     20 | true |
+|  7654 | MARTIN | SALESMAN  | 7698 | 1981-09-28 | 1250.00 | 1400.00 |     30 | true |
+|  7698 | BLAKE  | MANAGER   | 7839 | 1981-01-05 | 2850.00 |         |     30 | true |
+|  7782 | CLARK  | MANAGER   | 7839 | 1981-06-09 | 2450.00 |         |     10 | true |
+|  7788 | SCOTT  | ANALYST   | 7566 | 1987-04-19 | 3000.00 |         |     20 | true |
+|  7839 | KING   | PRESIDENT |      | 1981-11-17 | 5000.00 |         |     10 | true |
+|  7844 | TURNER | SALESMAN  | 7698 | 1981-09-08 | 1500.00 |    0.00 |     30 | true |
+|  7876 | ADAMS  | CLERK     | 7788 | 1987-05-23 | 1100.00 |         |     20 | true |
+|  7900 | JAMES  | CLERK     | 7698 | 1981-12-03 |  950.00 |         |     30 | true |
+|  7902 | FORD   | ANALYST   | 7566 | 1981-12-03 | 3000.00 |         |     20 | true |
+|  7934 | MILLER | CLERK     | 7782 | 1982-01-23 | 1300.00 |         |     10 | true |
++-------+--------+-----------+------+------------+---------+---------+--------+------+
+(14 rows)
+
+!ok
+
+# left side NOT NULL, right side nullable.
+select *
+from "scott".emp
+where empno <> some (values (7499),(NULL));
+
++-------+--------+-----------+------+------------+---------+---------+--------+
+| EMPNO | ENAME  | JOB       | MGR  | HIREDATE   | SAL     | COMM    | DEPTNO |
++-------+--------+-----------+------+------------+---------+---------+--------+
+|  7521 | WARD   | SALESMAN  | 7698 | 1981-02-22 | 1250.00 |  500.00 |     30 |
+|  7566 | JONES  | MANAGER   | 7839 | 1981-02-04 | 2975.00 |         |     20 |
+|  7654 | MARTIN | SALESMAN  | 7698 | 1981-09-28 | 1250.00 | 1400.00 |     30 |
+|  7698 | BLAKE  | MANAGER   | 7839 | 1981-01-05 | 2850.00 |         |     30 |
+|  7782 | CLARK  | MANAGER   | 7839 | 1981-06-09 | 2450.00 |         |     10 |
+|  7788 | SCOTT  | ANALYST   | 7566 | 1987-04-19 | 3000.00 |         |     20 |
+|  7839 | KING   | PRESIDENT |      | 1981-11-17 | 5000.00 |         |     10 |
+|  7844 | TURNER | SALESMAN  | 7698 | 1981-09-08 | 1500.00 |    0.00 |     30 |
+|  7876 | ADAMS  | CLERK     | 7788 | 1987-05-23 | 1100.00 |         |     20 |
+|  7900 | JAMES  | CLERK     | 7698 | 1981-12-03 |  950.00 |         |     30 |
+|  7902 | FORD   | ANALYST   | 7566 | 1981-12-03 | 3000.00 |         |     20 |
+|  7934 | MILLER | CLERK     | 7782 | 1982-01-23 | 1300.00 |         |     10 |
+|  7369 | SMITH  | CLERK     | 7902 | 1980-12-17 |  800.00 |         |     20 |
++-------+--------+-----------+------+------------+---------+---------+--------+
+(13 rows)
+
+!ok
+
+# Previous, as scalar sub-query.
+select *, empno <> some (values (7499), (NULL)) as x
+from "scott".emp;
+
++-------+--------+-----------+------+------------+---------+---------+--------+------+
+| EMPNO | ENAME  | JOB       | MGR  | HIREDATE   | SAL     | COMM    | DEPTNO | X    |
++-------+--------+-----------+------+------------+---------+---------+--------+------+
+|  7369 | SMITH  | CLERK     | 7902 | 1980-12-17 |  800.00 |         |     20 | true |
+|  7499 | ALLEN  | SALESMAN  | 7698 | 1981-02-20 | 1600.00 |  300.00 |     30 |      |
+|  7521 | WARD   | SALESMAN  | 7698 | 1981-02-22 | 1250.00 |  500.00 |     30 | true |
+|  7566 | JONES  | MANAGER   | 7839 | 1981-02-04 | 2975.00 |         |     20 | true |
+|  7654 | MARTIN | SALESMAN  | 7698 | 1981-09-28 | 1250.00 | 1400.00 |     30 | true |
+|  7698 | BLAKE  | MANAGER   | 7839 | 1981-01-05 | 2850.00 |         |     30 | true |
+|  7782 | CLARK  | MANAGER   | 7839 | 1981-06-09 | 2450.00 |         |     10 | true |
+|  7788 | SCOTT  | ANALYST   | 7566 | 1987-04-19 | 3000.00 |         |     20 | true |
+|  7839 | KING   | PRESIDENT |      | 1981-11-17 | 5000.00 |         |     10 | true |
+|  7844 | TURNER | SALESMAN  | 7698 | 1981-09-08 | 1500.00 |    0.00 |     30 | true |
+|  7876 | ADAMS  | CLERK     | 7788 | 1987-05-23 | 1100.00 |         |     20 | true |
+|  7900 | JAMES  | CLERK     | 7698 | 1981-12-03 |  950.00 |         |     30 | true |
+|  7902 | FORD   | ANALYST   | 7566 | 1981-12-03 | 3000.00 |         |     20 | true |
+|  7934 | MILLER | CLERK     | 7782 | 1982-01-23 | 1300.00 |         |     10 | true |
++-------+--------+-----------+------+------------+---------+---------+--------+------+
+(14 rows)
+
+!ok
+
+# left side NOT NULL, right side empty.
+select *
+from "scott".emp
+where empno <> some (select empno from "scott".emp where empno = 8000);
+
++-------+-------+-----+-----+----------+-----+------+--------+
+| EMPNO | ENAME | JOB | MGR | HIREDATE | SAL | COMM | DEPTNO |
++-------+-------+-----+-----+----------+-----+------+--------+
++-------+-------+-----+-----+----------+-----+------+--------+
+(0 rows)
+
+!ok
+
+# Previous, as scalar sub-query.
+select *, empno <> some (select empno from "scott".emp where empno = 8000) as x
+from "scott".emp;
+
++-------+--------+-----------+------+------------+---------+---------+--------+-------+
+| EMPNO | ENAME  | JOB       | MGR  | HIREDATE   | SAL     | COMM    | DEPTNO | X     |
++-------+--------+-----------+------+------------+---------+---------+--------+-------+
+|  7369 | SMITH  | CLERK     | 7902 | 1980-12-17 |  800.00 |         |     20 | false |
+|  7499 | ALLEN  | SALESMAN  | 7698 | 1981-02-20 | 1600.00 |  300.00 |     30 | false |
+|  7521 | WARD   | SALESMAN  | 7698 | 1981-02-22 | 1250.00 |  500.00 |     30 | false |
+|  7566 | JONES  | MANAGER   | 7839 | 1981-02-04 | 2975.00 |         |     20 | false |
+|  7654 | MARTIN | SALESMAN  | 7698 | 1981-09-28 | 1250.00 | 1400.00 |     30 | false |
+|  7698 | BLAKE  | MANAGER   | 7839 | 1981-01-05 | 2850.00 |         |     30 | false |
+|  7782 | CLARK  | MANAGER   | 7839 | 1981-06-09 | 2450.00 |         |     10 | false |
+|  7788 | SCOTT  | ANALYST   | 7566 | 1987-04-19 | 3000.00 |         |     20 | false |
+|  7839 | KING   | PRESIDENT |      | 1981-11-17 | 5000.00 |         |     10 | false |
+|  7844 | TURNER | SALESMAN  | 7698 | 1981-09-08 | 1500.00 |    0.00 |     30 | false |
+|  7876 | ADAMS  | CLERK     | 7788 | 1987-05-23 | 1100.00 |         |     20 | false |
+|  7900 | JAMES  | CLERK     | 7698 | 1981-12-03 |  950.00 |         |     30 | false |
+|  7902 | FORD   | ANALYST   | 7566 | 1981-12-03 | 3000.00 |         |     20 | false |
+|  7934 | MILLER | CLERK     | 7782 | 1982-01-23 | 1300.00 |         |     10 | false |
++-------+--------+-----------+------+------------+---------+---------+--------+-------+
+(14 rows)
+
+!ok
+
+# left side nullable, right side NOT NULL.
+select *
+from "scott".emp
+where emp.comm <> some (values (300), (500));
+
++-------+--------+----------+------+------------+---------+---------+--------+
+| EMPNO | ENAME  | JOB      | MGR  | HIREDATE   | SAL     | COMM    | DEPTNO |
++-------+--------+----------+------+------------+---------+---------+--------+
+|  7499 | ALLEN  | SALESMAN | 7698 | 1981-02-20 | 1600.00 |  300.00 |     30 |
+|  7521 | WARD   | SALESMAN | 7698 | 1981-02-22 | 1250.00 |  500.00 |     30 |
+|  7654 | MARTIN | SALESMAN | 7698 | 1981-09-28 | 1250.00 | 1400.00 |     30 |
+|  7844 | TURNER | SALESMAN | 7698 | 1981-09-08 | 1500.00 |    0.00 |     30 |
++-------+--------+----------+------+------------+---------+---------+--------+
+(4 rows)
+
+!ok
+
+# Previous, as scalar sub-query.
+select *, emp.comm <> some (values (300), (500)) as x
+from "scott".emp;
+
++-------+--------+-----------+------+------------+---------+---------+--------+------+
+| EMPNO | ENAME  | JOB       | MGR  | HIREDATE   | SAL     | COMM    | DEPTNO | X    |
++-------+--------+-----------+------+------------+---------+---------+--------+------+
+|  7369 | SMITH  | CLERK     | 7902 | 1980-12-17 |  800.00 |         |     20 |      |
+|  7499 | ALLEN  | SALESMAN  | 7698 | 1981-02-20 | 1600.00 |  300.00 |     30 | true |
+|  7521 | WARD   | SALESMAN  | 7698 | 1981-02-22 | 1250.00 |  500.00 |     30 | true |
+|  7566 | JONES  | MANAGER   | 7839 | 1981-02-04 | 2975.00 |         |     20 |      |
+|  7654 | MARTIN | SALESMAN  | 7698 | 1981-09-28 | 1250.00 | 1400.00 |     30 | true |
+|  7698 | BLAKE  | MANAGER   | 7839 | 1981-01-05 | 2850.00 |         |     30 |      |
+|  7782 | CLARK  | MANAGER   | 7839 | 1981-06-09 | 2450.00 |         |     10 |      |
+|  7788 | SCOTT  | ANALYST   | 7566 | 1987-04-19 | 3000.00 |         |     20 |      |
+|  7839 | KING   | PRESIDENT |      | 1981-11-17 | 5000.00 |         |     10 |      |
+|  7844 | TURNER | SALESMAN  | 7698 | 1981-09-08 | 1500.00 |    0.00 |     30 | true |
+|  7876 | ADAMS  | CLERK     | 7788 | 1987-05-23 | 1100.00 |         |     20 |      |
+|  7900 | JAMES  | CLERK     | 7698 | 1981-12-03 |  950.00 |         |     30 |      |
+|  7902 | FORD   | ANALYST   | 7566 | 1981-12-03 | 3000.00 |         |     20 |      |
+|  7934 | MILLER | CLERK     | 7782 | 1982-01-23 | 1300.00 |         |     10 |      |
++-------+--------+-----------+------+------------+---------+---------+--------+------+
+(14 rows)
+
+!ok
+
+# left side nullable, right side nullable.
+select *
+from "scott".emp
+where emp.comm <> some (select comm from "scott".emp);
+
++-------+--------+----------+------+------------+---------+---------+--------+
+| EMPNO | ENAME  | JOB      | MGR  | HIREDATE   | SAL     | COMM    | DEPTNO |
++-------+--------+----------+------+------------+---------+---------+--------+
+|  7499 | ALLEN  | SALESMAN | 7698 | 1981-02-20 | 1600.00 |  300.00 |     30 |
+|  7521 | WARD   | SALESMAN | 7698 | 1981-02-22 | 1250.00 |  500.00 |     30 |
+|  7654 | MARTIN | SALESMAN | 7698 | 1981-09-28 | 1250.00 | 1400.00 |     30 |
+|  7844 | TURNER | SALESMAN | 7698 | 1981-09-08 | 1500.00 |    0.00 |     30 |
++-------+--------+----------+------+------------+---------+---------+--------+
+(4 rows)
+
+!ok
+
+# Previous, as scalar sub-query.
+select *, emp.comm <> some (select comm from "scott".emp) as x
+from "scott".emp;
+
++-------+--------+-----------+------+------------+---------+---------+--------+------+
+| EMPNO | ENAME  | JOB       | MGR  | HIREDATE   | SAL     | COMM    | DEPTNO | X    |
++-------+--------+-----------+------+------------+---------+---------+--------+------+
+|  7369 | SMITH  | CLERK     | 7902 | 1980-12-17 |  800.00 |         |     20 |      |
+|  7499 | ALLEN  | SALESMAN  | 7698 | 1981-02-20 | 1600.00 |  300.00 |     30 | true |
+|  7521 | WARD   | SALESMAN  | 7698 | 1981-02-22 | 1250.00 |  500.00 |     30 | true |
+|  7566 | JONES  | MANAGER   | 7839 | 1981-02-04 | 2975.00 |         |     20 |      |
+|  7654 | MARTIN | SALESMAN  | 7698 | 1981-09-28 | 1250.00 | 1400.00 |     30 | true |
+|  7698 | BLAKE  | MANAGER   | 7839 | 1981-01-05 | 2850.00 |         |     30 |      |
+|  7782 | CLARK  | MANAGER   | 7839 | 1981-06-09 | 2450.00 |         |     10 |      |
+|  7788 | SCOTT  | ANALYST   | 7566 | 1987-04-19 | 3000.00 |         |     20 |      |
+|  7839 | KING   | PRESIDENT |      | 1981-11-17 | 5000.00 |         |     10 |      |
+|  7844 | TURNER | SALESMAN  | 7698 | 1981-09-08 | 1500.00 |    0.00 |     30 | true |
+|  7876 | ADAMS  | CLERK     | 7788 | 1987-05-23 | 1100.00 |         |     20 |      |
+|  7900 | JAMES  | CLERK     | 7698 | 1981-12-03 |  950.00 |         |     30 |      |
+|  7902 | FORD   | ANALYST   | 7566 | 1981-12-03 | 3000.00 |         |     20 |      |
+|  7934 | MILLER | CLERK     | 7782 | 1982-01-23 | 1300.00 |         |     10 |      |
++-------+--------+-----------+------+------------+---------+---------+--------+------+
+(14 rows)
+
+!ok
+
+# left side nullable, right side empty.
+select *
+from "scott".emp
+where emp.comm <> some (select comm from "scott".emp where comm = 800);
+
++-------+-------+-----+-----+----------+-----+------+--------+
+| EMPNO | ENAME | JOB | MGR | HIREDATE | SAL | COMM | DEPTNO |
++-------+-------+-----+-----+----------+-----+------+--------+
++-------+-------+-----+-----+----------+-----+------+--------+
+(0 rows)
+
+!ok
+
+# Previous, as scalar sub-query.
+select *, emp.comm <> some (select comm from "scott".emp where comm = 800) as x
+from "scott".emp;
+
++-------+--------+-----------+------+------------+---------+---------+--------+-------+
+| EMPNO | ENAME  | JOB       | MGR  | HIREDATE   | SAL     | COMM    | DEPTNO | X     |
++-------+--------+-----------+------+------------+---------+---------+--------+-------+
+|  7369 | SMITH  | CLERK     | 7902 | 1980-12-17 |  800.00 |         |     20 | false |
+|  7499 | ALLEN  | SALESMAN  | 7698 | 1981-02-20 | 1600.00 |  300.00 |     30 | false |
+|  7521 | WARD   | SALESMAN  | 7698 | 1981-02-22 | 1250.00 |  500.00 |     30 | false |
+|  7566 | JONES  | MANAGER   | 7839 | 1981-02-04 | 2975.00 |         |     20 | false |
+|  7654 | MARTIN | SALESMAN  | 7698 | 1981-09-28 | 1250.00 | 1400.00 |     30 | false |
+|  7698 | BLAKE  | MANAGER   | 7839 | 1981-01-05 | 2850.00 |         |     30 | false |
+|  7782 | CLARK  | MANAGER   | 7839 | 1981-06-09 | 2450.00 |         |     10 | false |
+|  7788 | SCOTT  | ANALYST   | 7566 | 1987-04-19 | 3000.00 |         |     20 | false |
+|  7839 | KING   | PRESIDENT |      | 1981-11-17 | 5000.00 |         |     10 | false |
+|  7844 | TURNER | SALESMAN  | 7698 | 1981-09-08 | 1500.00 |    0.00 |     30 | false |
+|  7876 | ADAMS  | CLERK     | 7788 | 1987-05-23 | 1100.00 |         |     20 | false |
+|  7900 | JAMES  | CLERK     | 7698 | 1981-12-03 |  950.00 |         |     30 | false |
+|  7902 | FORD   | ANALYST   | 7566 | 1981-12-03 | 3000.00 |         |     20 | false |
+|  7934 | MILLER | CLERK     | 7782 | 1982-01-23 | 1300.00 |         |     10 | false |
++-------+--------+-----------+------+------------+---------+---------+--------+-------+
+(14 rows)
+
+!ok
+
 # Sub-query is empty, so "< all" is trivially true. Even for null comm.
 select * from "scott".emp
 where comm < all (select comm from "scott".emp where 1 = 0)
diff --git a/core/src/test/resources/sql/sub-query.iq b/core/src/test/resources/sql/sub-query.iq
index 172dbe9..4200c47 100644
--- a/core/src/test/resources/sql/sub-query.iq
+++ b/core/src/test/resources/sql/sub-query.iq
@@ -2161,4 +2161,258 @@
 
 !ok
 
+!set outputformat mysql
+# Correlated SOME sub-query with not equality
+# Both sides Not NUll.
+select empno
+from "scott".emp emp1
+where empno <> some (select emp2.empno from "scott".emp emp2 where emp2.empno = emp1.empno);
+EnumerableCalc(expr#0..5=[{inputs}], expr#6=[<>($t2, $t1)], expr#7=[1], expr#8=[<=($t2, $t7)], expr#9=[<>($t0, $t3)], expr#10=[IS NULL($t4)], expr#11=[0], expr#12=[=($t1, $t11)], expr#13=[OR($t10, $t12)], expr#14=[IS NOT TRUE($t13)], expr#15=[AND($t6, $t8, $t9, $t14)], expr#16=[=($t2, $t7)], expr#17=[IS NOT NULL($t2)], expr#18=[AND($t6, $t17)], expr#19=[IS NOT TRUE($t18)], expr#20=[AND($t16, $t9, $t14, $t19)], expr#21=[AND($t6, $t8)], expr#22=[IS NOT TRUE($t21)], expr#23=[IS NOT TRUE($t16)], expr#24=[AND($t14, $t22, $t23)], expr#25=[OR($t15, $t20, $t24)], EMPNO=[$t0], $condition=[$t25])
+  EnumerableMergeJoin(condition=[=($0, $5)], joinType=[left])
+    EnumerableCalc(expr#0..7=[{inputs}], EMPNO=[$t0])
+      EnumerableTableScan(table=[[scott, EMP]])
+    EnumerableSort(sort0=[$4], dir0=[ASC])
+      EnumerableCalc(expr#0..7=[{inputs}], expr#8=[1:BIGINT], expr#9=[true], c=[$t8], d=[$t8], m=[$t0], trueLiteral=[$t9], EMPNO1=[$t0])
+        EnumerableTableScan(table=[[scott, EMP]])
+!plan
++-------+
+| EMPNO |
++-------+
++-------+
+(0 rows)
+
+!ok
+
+# Previous, as scalar sub-query.
+select empno, empno <> some (select emp2.empno from "scott".emp emp2 where emp2.empno = emp1.empno) as x
+from "scott".emp emp1;
+
++-------+-------+
+| EMPNO | X     |
++-------+-------+
+|  7369 | false |
+|  7499 | false |
+|  7521 | false |
+|  7566 | false |
+|  7654 | false |
+|  7698 | false |
+|  7782 | false |
+|  7788 | false |
+|  7839 | false |
+|  7844 | false |
+|  7876 | false |
+|  7900 | false |
+|  7902 | false |
+|  7934 | false |
++-------+-------+
+(14 rows)
+
+!ok
+
+# left side NOT NULL, correlated sub-query nullable.
+select *
+from "scott".emp emp1
+where empno <> some (select comm from "scott".emp where deptno = emp1.deptno);
+EnumerableCalc(expr#0..12=[{inputs}], expr#13=[<>($t9, $t8)], expr#14=[1], expr#15=[<=($t9, $t14)], expr#16=[AND($t13, $t15)], expr#17=[=($t9, $t14)], expr#18=[OR($t16, $t17)], expr#19=[<>($t0, $t10)], expr#20=[IS NULL($t11)], expr#21=[0], expr#22=[=($t8, $t21)], expr#23=[OR($t20, $t22)], expr#24=[IS NOT TRUE($t23)], expr#25=[AND($t18, $t19, $t24)], expr#26=[IS NOT TRUE($t18)], expr#27=[AND($t24, $t26)], expr#28=[OR($t25, $t27)], proj#0..7=[{exprs}], $condition=[$t28])
+  EnumerableMergeJoin(condition=[=($7, $12)], joinType=[left])
+    EnumerableSort(sort0=[$7], dir0=[ASC])
+      EnumerableTableScan(table=[[scott, EMP]])
+    EnumerableSort(sort0=[$4], dir0=[ASC])
+      EnumerableCalc(expr#0..3=[{inputs}], expr#4=[true], c=[$t1], d=[$t2], m=[$t3], trueLiteral=[$t4], DEPTNO=[$t0])
+        EnumerableAggregate(group=[{0}], c=[COUNT() FILTER $4], d=[COUNT($1) FILTER $3], m=[MIN($2) FILTER $4])
+          EnumerableCalc(expr#0..3=[{inputs}], expr#4=[0], expr#5=[=($t3, $t4)], expr#6=[1], expr#7=[=($t3, $t6)], DEPTNO=[$t1], COMM=[$t0], m=[$t2], $g_0=[$t5], $g_1=[$t7])
+            EnumerableAggregate(group=[{6, 7}], groups=[[{6, 7}, {7}]], m=[MAX($6)], $g=[GROUPING($7, $6)])
+              EnumerableCalc(expr#0..7=[{inputs}], expr#8=[IS NOT NULL($t7)], proj#0..7=[{exprs}], $condition=[$t8])
+                EnumerableTableScan(table=[[scott, EMP]])
+!plan
++-------+--------+----------+------+------------+---------+---------+--------+
+| EMPNO | ENAME  | JOB      | MGR  | HIREDATE   | SAL     | COMM    | DEPTNO |
++-------+--------+----------+------+------------+---------+---------+--------+
+|  7499 | ALLEN  | SALESMAN | 7698 | 1981-02-20 | 1600.00 |  300.00 |     30 |
+|  7521 | WARD   | SALESMAN | 7698 | 1981-02-22 | 1250.00 |  500.00 |     30 |
+|  7654 | MARTIN | SALESMAN | 7698 | 1981-09-28 | 1250.00 | 1400.00 |     30 |
+|  7698 | BLAKE  | MANAGER  | 7839 | 1981-01-05 | 2850.00 |         |     30 |
+|  7844 | TURNER | SALESMAN | 7698 | 1981-09-08 | 1500.00 |    0.00 |     30 |
+|  7900 | JAMES  | CLERK    | 7698 | 1981-12-03 |  950.00 |         |     30 |
++-------+--------+----------+------+------------+---------+---------+--------+
+(6 rows)
+
+!ok
+
+# Previous, as scalar sub-query.
+select *, empno <> some (select comm from "scott".emp where deptno = emp1.deptno) as x
+from "scott".emp as emp1;
+
++-------+--------+-----------+------+------------+---------+---------+--------+------+
+| EMPNO | ENAME  | JOB       | MGR  | HIREDATE   | SAL     | COMM    | DEPTNO | X    |
++-------+--------+-----------+------+------------+---------+---------+--------+------+
+|  7369 | SMITH  | CLERK     | 7902 | 1980-12-17 |  800.00 |         |     20 |      |
+|  7499 | ALLEN  | SALESMAN  | 7698 | 1981-02-20 | 1600.00 |  300.00 |     30 | true |
+|  7521 | WARD   | SALESMAN  | 7698 | 1981-02-22 | 1250.00 |  500.00 |     30 | true |
+|  7566 | JONES  | MANAGER   | 7839 | 1981-02-04 | 2975.00 |         |     20 |      |
+|  7654 | MARTIN | SALESMAN  | 7698 | 1981-09-28 | 1250.00 | 1400.00 |     30 | true |
+|  7698 | BLAKE  | MANAGER   | 7839 | 1981-01-05 | 2850.00 |         |     30 | true |
+|  7782 | CLARK  | MANAGER   | 7839 | 1981-06-09 | 2450.00 |         |     10 |      |
+|  7788 | SCOTT  | ANALYST   | 7566 | 1987-04-19 | 3000.00 |         |     20 |      |
+|  7839 | KING   | PRESIDENT |      | 1981-11-17 | 5000.00 |         |     10 |      |
+|  7844 | TURNER | SALESMAN  | 7698 | 1981-09-08 | 1500.00 |    0.00 |     30 | true |
+|  7876 | ADAMS  | CLERK     | 7788 | 1987-05-23 | 1100.00 |         |     20 |      |
+|  7900 | JAMES  | CLERK     | 7698 | 1981-12-03 |  950.00 |         |     30 | true |
+|  7902 | FORD   | ANALYST   | 7566 | 1981-12-03 | 3000.00 |         |     20 |      |
+|  7934 | MILLER | CLERK     | 7782 | 1982-01-23 | 1300.00 |         |     10 |      |
++-------+--------+-----------+------+------------+---------+---------+--------+------+
+(14 rows)
+
+!ok
+
+# left side NOT NULL, correlated sub-query empty.
+select *
+from "scott".emp as emp1
+where empno <> some (select 2 from "scott".dept dept1 where dept1.deptno = emp1.empno);
+EnumerableCalc(expr#0..12=[{inputs}], expr#13=[<>($t9, $t8)], expr#14=[1], expr#15=[<=($t9, $t14)], expr#16=[<>($t0, $t10)], expr#17=[IS NULL($t11)], expr#18=[0], expr#19=[=($t8, $t18)], expr#20=[OR($t17, $t19)], expr#21=[IS NOT TRUE($t20)], expr#22=[AND($t13, $t15, $t16, $t21)], expr#23=[=($t9, $t14)], expr#24=[IS NOT NULL($t9)], expr#25=[AND($t13, $t24)], expr#26=[IS NOT TRUE($t25)], expr#27=[AND($t23, $t16, $t21, $t26)], expr#28=[AND($t13, $t15)], expr#29=[IS NOT TRUE($t28)], expr#30=[IS NOT TRUE($t23)], expr#31=[AND($t21, $t29, $t30)], expr#32=[OR($t22, $t27, $t31)], proj#0..7=[{exprs}], $condition=[$t32])
+  EnumerableMergeJoin(condition=[=($0, $12)], joinType=[left])
+    EnumerableTableScan(table=[[scott, EMP]])
+    EnumerableSort(sort0=[$4], dir0=[ASC])
+      EnumerableCalc(expr#0..3=[{inputs}], expr#4=[CAST($t3):INTEGER NOT NULL], expr#5=[true], c=[$t1], d=[$t2], m=[$t4], trueLiteral=[$t5], DEPTNO0=[$t0])
+        EnumerableAggregate(group=[{0}], c=[COUNT() FILTER $4], d=[COUNT($1) FILTER $3], m=[MIN($2) FILTER $4])
+          EnumerableCalc(expr#0..3=[{inputs}], expr#4=[0], expr#5=[=($t3, $t4)], expr#6=[1], expr#7=[=($t3, $t6)], proj#0..2=[{exprs}], $g_0=[$t5], $g_1=[$t7])
+            EnumerableAggregate(group=[{0, 1}], groups=[[{0, 1}, {0}]], m=[MAX($1)], $g=[GROUPING($0, $1)])
+              EnumerableCalc(expr#0..2=[{inputs}], expr#3=[CAST($t0):SMALLINT NOT NULL], expr#4=[2], DEPTNO0=[$t3], EXPR$0=[$t4])
+                EnumerableTableScan(table=[[scott, DEPT]])
+!plan
++-------+-------+-----+-----+----------+-----+------+--------+
+| EMPNO | ENAME | JOB | MGR | HIREDATE | SAL | COMM | DEPTNO |
++-------+-------+-----+-----+----------+-----+------+--------+
++-------+-------+-----+-----+----------+-----+------+--------+
+(0 rows)
+
+!ok
+
+# Previous, as scalar sub-query.
+select *, empno <> some (select 2 from "scott".dept dept1 where dept1.deptno = emp1.empno) as x
+from "scott".emp as emp1;
+
++-------+--------+-----------+------+------------+---------+---------+--------+-------+
+| EMPNO | ENAME  | JOB       | MGR  | HIREDATE   | SAL     | COMM    | DEPTNO | X     |
++-------+--------+-----------+------+------------+---------+---------+--------+-------+
+|  7369 | SMITH  | CLERK     | 7902 | 1980-12-17 |  800.00 |         |     20 | false |
+|  7499 | ALLEN  | SALESMAN  | 7698 | 1981-02-20 | 1600.00 |  300.00 |     30 | false |
+|  7521 | WARD   | SALESMAN  | 7698 | 1981-02-22 | 1250.00 |  500.00 |     30 | false |
+|  7566 | JONES  | MANAGER   | 7839 | 1981-02-04 | 2975.00 |         |     20 | false |
+|  7654 | MARTIN | SALESMAN  | 7698 | 1981-09-28 | 1250.00 | 1400.00 |     30 | false |
+|  7698 | BLAKE  | MANAGER   | 7839 | 1981-01-05 | 2850.00 |         |     30 | false |
+|  7782 | CLARK  | MANAGER   | 7839 | 1981-06-09 | 2450.00 |         |     10 | false |
+|  7788 | SCOTT  | ANALYST   | 7566 | 1987-04-19 | 3000.00 |         |     20 | false |
+|  7839 | KING   | PRESIDENT |      | 1981-11-17 | 5000.00 |         |     10 | false |
+|  7844 | TURNER | SALESMAN  | 7698 | 1981-09-08 | 1500.00 |    0.00 |     30 | false |
+|  7876 | ADAMS  | CLERK     | 7788 | 1987-05-23 | 1100.00 |         |     20 | false |
+|  7900 | JAMES  | CLERK     | 7698 | 1981-12-03 |  950.00 |         |     30 | false |
+|  7902 | FORD   | ANALYST   | 7566 | 1981-12-03 | 3000.00 |         |     20 | false |
+|  7934 | MILLER | CLERK     | 7782 | 1982-01-23 | 1300.00 |         |     10 | false |
++-------+--------+-----------+------+------------+---------+---------+--------+-------+
+(14 rows)
+
+!ok
+
+# left side nullable, correlated sub-query empty.
+select *
+from "scott".emp as emp1
+where comm <> some (select 2 from "scott".dept dept1 where dept1.deptno = emp1.empno);
+EnumerableCalc(expr#0..12=[{inputs}], expr#13=[<>($t9, $t8)], expr#14=[1], expr#15=[<=($t9, $t14)], expr#16=[AND($t13, $t15)], expr#17=[=($t9, $t14)], expr#18=[OR($t16, $t17)], expr#19=[<>($t6, $t10)], expr#20=[IS NULL($t11)], expr#21=[IS NULL($t6)], expr#22=[0], expr#23=[=($t8, $t22)], expr#24=[OR($t20, $t21, $t23)], expr#25=[IS NOT TRUE($t24)], expr#26=[AND($t18, $t19, $t25)], expr#27=[IS NOT TRUE($t18)], expr#28=[AND($t25, $t27)], expr#29=[OR($t26, $t28)], proj#0..7=[{exprs}], $condition=[$t29])
+  EnumerableMergeJoin(condition=[=($0, $12)], joinType=[left])
+    EnumerableTableScan(table=[[scott, EMP]])
+    EnumerableSort(sort0=[$4], dir0=[ASC])
+      EnumerableCalc(expr#0..3=[{inputs}], expr#4=[CAST($t3):INTEGER NOT NULL], expr#5=[true], c=[$t1], d=[$t2], m=[$t4], trueLiteral=[$t5], DEPTNO0=[$t0])
+        EnumerableAggregate(group=[{0}], c=[COUNT() FILTER $4], d=[COUNT($1) FILTER $3], m=[MIN($2) FILTER $4])
+          EnumerableCalc(expr#0..3=[{inputs}], expr#4=[0], expr#5=[=($t3, $t4)], expr#6=[1], expr#7=[=($t3, $t6)], proj#0..2=[{exprs}], $g_0=[$t5], $g_1=[$t7])
+            EnumerableAggregate(group=[{0, 1}], groups=[[{0, 1}, {0}]], m=[MAX($1)], $g=[GROUPING($0, $1)])
+              EnumerableCalc(expr#0..2=[{inputs}], expr#3=[CAST($t0):SMALLINT NOT NULL], expr#4=[2], DEPTNO0=[$t3], EXPR$0=[$t4])
+                EnumerableTableScan(table=[[scott, DEPT]])
+!plan
++-------+-------+-----+-----+----------+-----+------+--------+
+| EMPNO | ENAME | JOB | MGR | HIREDATE | SAL | COMM | DEPTNO |
++-------+-------+-----+-----+----------+-----+------+--------+
++-------+-------+-----+-----+----------+-----+------+--------+
+(0 rows)
+
+!ok
+
+# Previous, as scalar sub-query.
+select *, comm <> some (select 2 from "scott".dept dept1 where dept1.deptno = emp1.empno) as x
+from "scott".emp as emp1;
+
++-------+--------+-----------+------+------------+---------+---------+--------+-------+
+| EMPNO | ENAME  | JOB       | MGR  | HIREDATE   | SAL     | COMM    | DEPTNO | X     |
++-------+--------+-----------+------+------------+---------+---------+--------+-------+
+|  7369 | SMITH  | CLERK     | 7902 | 1980-12-17 |  800.00 |         |     20 | false |
+|  7499 | ALLEN  | SALESMAN  | 7698 | 1981-02-20 | 1600.00 |  300.00 |     30 | false |
+|  7521 | WARD   | SALESMAN  | 7698 | 1981-02-22 | 1250.00 |  500.00 |     30 | false |
+|  7566 | JONES  | MANAGER   | 7839 | 1981-02-04 | 2975.00 |         |     20 | false |
+|  7654 | MARTIN | SALESMAN  | 7698 | 1981-09-28 | 1250.00 | 1400.00 |     30 | false |
+|  7698 | BLAKE  | MANAGER   | 7839 | 1981-01-05 | 2850.00 |         |     30 | false |
+|  7782 | CLARK  | MANAGER   | 7839 | 1981-06-09 | 2450.00 |         |     10 | false |
+|  7788 | SCOTT  | ANALYST   | 7566 | 1987-04-19 | 3000.00 |         |     20 | false |
+|  7839 | KING   | PRESIDENT |      | 1981-11-17 | 5000.00 |         |     10 | false |
+|  7844 | TURNER | SALESMAN  | 7698 | 1981-09-08 | 1500.00 |    0.00 |     30 | false |
+|  7876 | ADAMS  | CLERK     | 7788 | 1987-05-23 | 1100.00 |         |     20 | false |
+|  7900 | JAMES  | CLERK     | 7698 | 1981-12-03 |  950.00 |         |     30 | false |
+|  7902 | FORD   | ANALYST   | 7566 | 1981-12-03 | 3000.00 |         |     20 | false |
+|  7934 | MILLER | CLERK     | 7782 | 1982-01-23 | 1300.00 |         |     10 | false |
++-------+--------+-----------+------+------------+---------+---------+--------+-------+
+(14 rows)
+
+!ok
+
+# left side nullable, correlated sub-query nullable.
+select *
+from "scott".emp emp1
+where emp1.comm <> some (select comm from "scott".emp emp2 where emp2.sal = emp1.sal);
+EnumerableCalc(expr#0..12=[{inputs}], expr#13=[<>($t9, $t8)], expr#14=[1], expr#15=[<=($t9, $t14)], expr#16=[AND($t13, $t15)], expr#17=[=($t9, $t14)], expr#18=[OR($t16, $t17)], expr#19=[<>($t6, $t10)], expr#20=[IS NULL($t11)], expr#21=[IS NULL($t6)], expr#22=[0], expr#23=[=($t8, $t22)], expr#24=[OR($t20, $t21, $t23)], expr#25=[IS NOT TRUE($t24)], expr#26=[AND($t18, $t19, $t25)], expr#27=[IS NOT TRUE($t18)], expr#28=[AND($t25, $t27)], expr#29=[OR($t26, $t28)], proj#0..7=[{exprs}], $condition=[$t29])
+  EnumerableMergeJoin(condition=[=($5, $12)], joinType=[left])
+    EnumerableSort(sort0=[$5], dir0=[ASC])
+      EnumerableTableScan(table=[[scott, EMP]])
+    EnumerableSort(sort0=[$4], dir0=[ASC])
+      EnumerableCalc(expr#0..3=[{inputs}], expr#4=[true], c=[$t1], d=[$t2], m=[$t3], trueLiteral=[$t4], SAL=[$t0])
+        EnumerableAggregate(group=[{0}], c=[COUNT() FILTER $4], d=[COUNT($1) FILTER $3], m=[MIN($2) FILTER $4])
+          EnumerableCalc(expr#0..3=[{inputs}], expr#4=[0], expr#5=[=($t3, $t4)], expr#6=[1], expr#7=[=($t3, $t6)], proj#0..2=[{exprs}], $g_0=[$t5], $g_1=[$t7])
+            EnumerableAggregate(group=[{5, 6}], groups=[[{5, 6}, {5}]], m=[MAX($6)], $g=[GROUPING($5, $6)])
+              EnumerableCalc(expr#0..7=[{inputs}], expr#8=[IS NOT NULL($t5)], proj#0..7=[{exprs}], $condition=[$t8])
+                EnumerableTableScan(table=[[scott, EMP]])
+!plan
++-------+--------+----------+------+------------+---------+---------+--------+
+| EMPNO | ENAME  | JOB      | MGR  | HIREDATE   | SAL     | COMM    | DEPTNO |
++-------+--------+----------+------+------------+---------+---------+--------+
+|  7521 | WARD   | SALESMAN | 7698 | 1981-02-22 | 1250.00 |  500.00 |     30 |
+|  7654 | MARTIN | SALESMAN | 7698 | 1981-09-28 | 1250.00 | 1400.00 |     30 |
++-------+--------+----------+------+------------+---------+---------+--------+
+(2 rows)
+
+!ok
+
+# Previous, as scalar sub-query.
+select *, emp1.comm <> some (select comm from "scott".emp where sal = emp1.sal) as x
+from "scott".emp emp1;
+
++-------+--------+-----------+------+------------+---------+---------+--------+-------+
+| EMPNO | ENAME  | JOB       | MGR  | HIREDATE   | SAL     | COMM    | DEPTNO | X     |
++-------+--------+-----------+------+------------+---------+---------+--------+-------+
+|  7369 | SMITH  | CLERK     | 7902 | 1980-12-17 |  800.00 |         |     20 |       |
+|  7499 | ALLEN  | SALESMAN  | 7698 | 1981-02-20 | 1600.00 |  300.00 |     30 | false |
+|  7521 | WARD   | SALESMAN  | 7698 | 1981-02-22 | 1250.00 |  500.00 |     30 | true  |
+|  7566 | JONES  | MANAGER   | 7839 | 1981-02-04 | 2975.00 |         |     20 |       |
+|  7654 | MARTIN | SALESMAN  | 7698 | 1981-09-28 | 1250.00 | 1400.00 |     30 | true  |
+|  7698 | BLAKE  | MANAGER   | 7839 | 1981-01-05 | 2850.00 |         |     30 |       |
+|  7782 | CLARK  | MANAGER   | 7839 | 1981-06-09 | 2450.00 |         |     10 |       |
+|  7788 | SCOTT  | ANALYST   | 7566 | 1987-04-19 | 3000.00 |         |     20 |       |
+|  7839 | KING   | PRESIDENT |      | 1981-11-17 | 5000.00 |         |     10 |       |
+|  7844 | TURNER | SALESMAN  | 7698 | 1981-09-08 | 1500.00 |    0.00 |     30 | false |
+|  7876 | ADAMS  | CLERK     | 7788 | 1987-05-23 | 1100.00 |         |     20 |       |
+|  7900 | JAMES  | CLERK     | 7698 | 1981-12-03 |  950.00 |         |     30 |       |
+|  7902 | FORD   | ANALYST   | 7566 | 1981-12-03 | 3000.00 |         |     20 |       |
+|  7934 | MILLER | CLERK     | 7782 | 1982-01-23 | 1300.00 |         |     10 |       |
++-------+--------+-----------+------+------------+---------+---------+--------+-------+
+(14 rows)
+
+!ok
+
 # End sub-query.iq