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<h1 title="程序包" class="title">程序包&nbsp;org.apache.calcite.rex</h1>
<div class="docSummary">
<div class="block">Provides a language for representing row-expressions.</div>
</div>
<p>请参阅:&nbsp;<a href="#package.description">说明</a></p>
</div>
<div class="contentContainer">
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<table class="typeSummary" border="0" cellpadding="3" cellspacing="0" summary="接口概要表, 列表接口和解释">
<caption><span>接口概要</span><span class="tabEnd">&nbsp;</span></caption>
<tr>
<th class="colFirst" scope="col">接口</th>
<th class="colLast" scope="col">说明</th>
</tr>
<tbody>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexAction.html" title="org.apache.calcite.rex中的接口">RexAction</a></td>
<td class="colLast">已过时</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexBiVisitor.html" title="org.apache.calcite.rex中的接口">RexBiVisitor</a>&lt;R,P&gt;</td>
<td class="colLast">
<div class="block">Visitor pattern for traversing a tree of <a href="../../../../org/apache/calcite/rex/RexNode.html" title="org.apache.calcite.rex中的类"><code>RexNode</code></a> objects
and passing a payload to each.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexExecutor.html" title="org.apache.calcite.rex中的接口">RexExecutor</a></td>
<td class="colLast">
<div class="block">Can reduce expressions, writing a literal for each into a list.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexNode.Closeable.html" title="org.apache.calcite.rex中的接口">RexNode.Closeable</a></td>
<td class="colLast">
<div class="block">Removes a Hook after use.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexPattern.html" title="org.apache.calcite.rex中的接口">RexPattern</a></td>
<td class="colLast">已过时</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexSqlConvertlet.html" title="org.apache.calcite.rex中的接口">RexSqlConvertlet</a></td>
<td class="colLast">
<div class="block">Converts a <a href="../../../../org/apache/calcite/rex/RexNode.html" title="org.apache.calcite.rex中的类"><code>RexNode</code></a> expression into a <a href="../../../../org/apache/calcite/sql/SqlNode.html" title="org.apache.calcite.sql中的类"><code>SqlNode</code></a> expression.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexSqlConvertletTable.html" title="org.apache.calcite.rex中的接口">RexSqlConvertletTable</a></td>
<td class="colLast">
<div class="block">Collection of <a href="../../../../org/apache/calcite/rex/RexSqlConvertlet.html" title="org.apache.calcite.rex中的接口"><code>RexSqlConvertlet</code></a>s.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexToSqlNodeConverter.html" title="org.apache.calcite.rex中的接口">RexToSqlNodeConverter</a></td>
<td class="colLast">
<div class="block">Converts expressions from <a href="../../../../org/apache/calcite/rex/RexNode.html" title="org.apache.calcite.rex中的类"><code>RexNode</code></a> to <a href="../../../../org/apache/calcite/sql/SqlNode.html" title="org.apache.calcite.sql中的类"><code>SqlNode</code></a>.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexVisitor.html" title="org.apache.calcite.rex中的接口">RexVisitor</a>&lt;R&gt;</td>
<td class="colLast">
<div class="block">Visitor pattern for traversing a tree of <a href="../../../../org/apache/calcite/rex/RexNode.html" title="org.apache.calcite.rex中的类"><code>RexNode</code></a> objects.</div>
</td>
</tr>
</tbody>
</table>
</li>
<li class="blockList">
<table class="typeSummary" border="0" cellpadding="3" cellspacing="0" summary="类概要表, 列表类和解释">
<caption><span>类概要</span><span class="tabEnd">&nbsp;</span></caption>
<tr>
<th class="colFirst" scope="col">类</th>
<th class="colLast" scope="col">说明</th>
</tr>
<tbody>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/LogicVisitor.html" title="org.apache.calcite.rex中的类">LogicVisitor</a></td>
<td class="colLast">
<div class="block">Visitor pattern for traversing a tree of <a href="../../../../org/apache/calcite/rex/RexNode.html" title="org.apache.calcite.rex中的类"><code>RexNode</code></a> objects.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexAnalyzer.html" title="org.apache.calcite.rex中的类">RexAnalyzer</a></td>
<td class="colLast">
<div class="block">Analyzes an expression, figures out what are the unbound variables,
assigns a variety of values to each unbound variable, and evaluates
the expression.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexBuilder.html" title="org.apache.calcite.rex中的类">RexBuilder</a></td>
<td class="colLast">
<div class="block">Factory for row expressions.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexCall.html" title="org.apache.calcite.rex中的类">RexCall</a></td>
<td class="colLast">
<div class="block">An expression formed by a call to an operator with zero or more expressions
as operands.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexCallBinding.html" title="org.apache.calcite.rex中的类">RexCallBinding</a></td>
<td class="colLast">
<div class="block"><code>RexCallBinding</code> implements <a href="../../../../org/apache/calcite/sql/SqlOperatorBinding.html" title="org.apache.calcite.sql中的类"><code>SqlOperatorBinding</code></a> by
referring to an underlying collection of <a href="../../../../org/apache/calcite/rex/RexNode.html" title="org.apache.calcite.rex中的类"><code>RexNode</code></a> operands.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexChecker.html" title="org.apache.calcite.rex中的类">RexChecker</a></td>
<td class="colLast">
<div class="block">Visitor which checks the validity of a <a href="../../../../org/apache/calcite/rex/RexNode.html" title="org.apache.calcite.rex中的类"><code>RexNode</code></a> expression.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexCorrelVariable.html" title="org.apache.calcite.rex中的类">RexCorrelVariable</a></td>
<td class="colLast">
<div class="block">Reference to the current row of a correlating relational expression.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexDynamicParam.html" title="org.apache.calcite.rex中的类">RexDynamicParam</a></td>
<td class="colLast">
<div class="block">Dynamic parameter reference in a row-expression.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexExecutable.html" title="org.apache.calcite.rex中的类">RexExecutable</a></td>
<td class="colLast">
<div class="block">Result of compiling code generated from a <a href="../../../../org/apache/calcite/rex/RexNode.html" title="org.apache.calcite.rex中的类"><code>RexNode</code></a> expression.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexExecutorImpl.html" title="org.apache.calcite.rex中的类">RexExecutorImpl</a></td>
<td class="colLast">
<div class="block">Evaluates a <a href="../../../../org/apache/calcite/rex/RexNode.html" title="org.apache.calcite.rex中的类"><code>RexNode</code></a> expression.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexFieldAccess.html" title="org.apache.calcite.rex中的类">RexFieldAccess</a></td>
<td class="colLast">
<div class="block">Access to a field of a row-expression.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexFieldCollation.html" title="org.apache.calcite.rex中的类">RexFieldCollation</a></td>
<td class="colLast">
<div class="block">Expression combined with sort flags (DESCENDING, NULLS LAST).</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexInputRef.html" title="org.apache.calcite.rex中的类">RexInputRef</a></td>
<td class="colLast">
<div class="block">Variable which references a field of an input relational expression.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexInterpreter.html" title="org.apache.calcite.rex中的类">RexInterpreter</a></td>
<td class="colLast">
<div class="block">Evaluates <a href="../../../../org/apache/calcite/rex/RexNode.html" title="org.apache.calcite.rex中的类"><code>RexNode</code></a> expressions.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexLiteral.html" title="org.apache.calcite.rex中的类">RexLiteral</a></td>
<td class="colLast">
<div class="block">Constant value in a row-expression.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexLocalRef.html" title="org.apache.calcite.rex中的类">RexLocalRef</a></td>
<td class="colLast">
<div class="block">Local variable.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexMultisetUtil.html" title="org.apache.calcite.rex中的类">RexMultisetUtil</a></td>
<td class="colLast">
<div class="block">Utility class for various methods related to multisets.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexNode.html" title="org.apache.calcite.rex中的类">RexNode</a></td>
<td class="colLast">
<div class="block">Row expression.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexOver.html" title="org.apache.calcite.rex中的类">RexOver</a></td>
<td class="colLast">
<div class="block">Call to an aggregate function over a window.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexPatternFieldRef.html" title="org.apache.calcite.rex中的类">RexPatternFieldRef</a></td>
<td class="colLast">
<div class="block">Variable which references a field of an input relational expression</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexPermutationShuttle.html" title="org.apache.calcite.rex中的类">RexPermutationShuttle</a></td>
<td class="colLast">
<div class="block">Visitor which replaces <a href="../../../../org/apache/calcite/rex/RexLocalRef.html" title="org.apache.calcite.rex中的类"><code>RexLocalRef</code></a> objects after the expressions in a
<a href="../../../../org/apache/calcite/rex/RexProgram.html" title="org.apache.calcite.rex中的类"><code>RexProgram</code></a> have been reordered.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexPermuteInputsShuttle.html" title="org.apache.calcite.rex中的类">RexPermuteInputsShuttle</a></td>
<td class="colLast">
<div class="block">Shuttle which applies a permutation to its input fields.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexProgram.html" title="org.apache.calcite.rex中的类">RexProgram</a></td>
<td class="colLast">
<div class="block">A collection of expressions which read inputs, compute output expressions,
and optionally use a condition to filter rows.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexProgramBuilder.html" title="org.apache.calcite.rex中的类">RexProgramBuilder</a></td>
<td class="colLast">
<div class="block">Workspace for constructing a <a href="../../../../org/apache/calcite/rex/RexProgram.html" title="org.apache.calcite.rex中的类"><code>RexProgram</code></a>.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexRangeRef.html" title="org.apache.calcite.rex中的类">RexRangeRef</a></td>
<td class="colLast">
<div class="block">Reference to a range of columns.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexShuttle.html" title="org.apache.calcite.rex中的类">RexShuttle</a></td>
<td class="colLast">
<div class="block">Passes over a row-expression, calling a handler method for each node,
appropriate to the type of the node.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexSimplify.html" title="org.apache.calcite.rex中的类">RexSimplify</a></td>
<td class="colLast">
<div class="block">Context required to simplify a row-expression.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexSlot.html" title="org.apache.calcite.rex中的类">RexSlot</a></td>
<td class="colLast">
<div class="block">Abstract base class for <a href="../../../../org/apache/calcite/rex/RexInputRef.html" title="org.apache.calcite.rex中的类"><code>RexInputRef</code></a> and <a href="../../../../org/apache/calcite/rex/RexLocalRef.html" title="org.apache.calcite.rex中的类"><code>RexLocalRef</code></a>.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexSlot.SelfPopulatingList.html" title="org.apache.calcite.rex中的类">RexSlot.SelfPopulatingList</a></td>
<td class="colLast">
<div class="block">Thread-safe list that populates itself if you make a reference beyond
the end of the list.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexSqlReflectiveConvertletTable.html" title="org.apache.calcite.rex中的类">RexSqlReflectiveConvertletTable</a></td>
<td class="colLast">
<div class="block">Implementation of <a href="../../../../org/apache/calcite/rex/RexSqlConvertletTable.html" title="org.apache.calcite.rex中的接口"><code>RexSqlConvertletTable</code></a>.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexSqlStandardConvertletTable.html" title="org.apache.calcite.rex中的类">RexSqlStandardConvertletTable</a></td>
<td class="colLast">
<div class="block">Standard implementation of <a href="../../../../org/apache/calcite/rex/RexSqlConvertletTable.html" title="org.apache.calcite.rex中的接口"><code>RexSqlConvertletTable</code></a>.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexSubQuery.html" title="org.apache.calcite.rex中的类">RexSubQuery</a></td>
<td class="colLast">
<div class="block">Scalar expression that represents an IN, EXISTS or scalar sub-query.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexTableInputRef.html" title="org.apache.calcite.rex中的类">RexTableInputRef</a></td>
<td class="colLast">
<div class="block">Variable which references a column of a table occurrence in a relational plan.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexTableInputRef.RelTableRef.html" title="org.apache.calcite.rex中的类">RexTableInputRef.RelTableRef</a></td>
<td class="colLast">
<div class="block">Identifies uniquely a table by its qualified name and its entity number (occurrence)</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexToSqlNodeConverterImpl.html" title="org.apache.calcite.rex中的类">RexToSqlNodeConverterImpl</a></td>
<td class="colLast">
<div class="block">Standard implementation of <a href="../../../../org/apache/calcite/rex/RexToSqlNodeConverter.html" title="org.apache.calcite.rex中的接口"><code>RexToSqlNodeConverter</code></a>.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexTransformer.html" title="org.apache.calcite.rex中的类">RexTransformer</a></td>
<td class="colLast">
<div class="block">Takes a tree of <a href="../../../../org/apache/calcite/rex/RexNode.html" title="org.apache.calcite.rex中的类"><code>RexNode</code></a> objects and transforms it into another in one
sense equivalent tree.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexUtil.html" title="org.apache.calcite.rex中的类">RexUtil</a></td>
<td class="colLast">
<div class="block">Utility methods concerning row-expressions.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexUtil.ExprSimplifier.html" title="org.apache.calcite.rex中的类">RexUtil.ExprSimplifier</a></td>
<td class="colLast">已过时</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexUtil.FieldAccessFinder.html" title="org.apache.calcite.rex中的类">RexUtil.FieldAccessFinder</a></td>
<td class="colLast">
<div class="block">Visitor which builds a bitmap of the inputs used by an expression.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexUtil.FixNullabilityShuttle.html" title="org.apache.calcite.rex中的类">RexUtil.FixNullabilityShuttle</a></td>
<td class="colLast">
<div class="block">Shuttle that fixes up an expression to match changes in nullability of
input fields.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexUtil.SubQueryFinder.html" title="org.apache.calcite.rex中的类">RexUtil.SubQueryFinder</a></td>
<td class="colLast">
<div class="block">Visitor that throws <a href="../../../../org/apache/calcite/util/Util.FoundOne.html" title="org.apache.calcite.util中的类"><code>Util.FoundOne</code></a> if
applied to an expression that contains a <a href="../../../../org/apache/calcite/rex/RexSubQuery.html" title="org.apache.calcite.rex中的类"><code>RexSubQuery</code></a>.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexVariable.html" title="org.apache.calcite.rex中的类">RexVariable</a></td>
<td class="colLast">
<div class="block">A row-expression which references a field.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexVisitorImpl.html" title="org.apache.calcite.rex中的类">RexVisitorImpl</a>&lt;R&gt;</td>
<td class="colLast">
<div class="block">Default implementation of <a href="../../../../org/apache/calcite/rex/RexVisitor.html" title="org.apache.calcite.rex中的接口"><code>RexVisitor</code></a>, which visits each node but does
nothing while it's there.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexWindow.html" title="org.apache.calcite.rex中的类">RexWindow</a></td>
<td class="colLast">
<div class="block">Specification of the window of rows over which a <a href="../../../../org/apache/calcite/rex/RexOver.html" title="org.apache.calcite.rex中的类"><code>RexOver</code></a> windowed
aggregate is evaluated.</div>
</td>
</tr>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexWindowBound.html" title="org.apache.calcite.rex中的类">RexWindowBound</a></td>
<td class="colLast">
<div class="block">Abstracts "XX PRECEDING/FOLLOWING" and "CURRENT ROW" bounds for windowed
aggregates.</div>
</td>
</tr>
</tbody>
</table>
</li>
<li class="blockList">
<table class="typeSummary" border="0" cellpadding="3" cellspacing="0" summary="枚举概要表, 列表枚举和解释">
<caption><span>枚举概要</span><span class="tabEnd">&nbsp;</span></caption>
<tr>
<th class="colFirst" scope="col">枚举</th>
<th class="colLast" scope="col">说明</th>
</tr>
<tbody>
<tr class="altColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexDigestIncludeType.html" title="org.apache.calcite.rex中的枚举">RexDigestIncludeType</a></td>
<td class="colLast">
<div class="block">Defines if type information should be printed for <a href="../../../../org/apache/calcite/rex/RexLiteral.html" title="org.apache.calcite.rex中的类"><code>RexLiteral</code></a>.</div>
</td>
</tr>
<tr class="rowColor">
<td class="colFirst"><a href="../../../../org/apache/calcite/rex/RexUnknownAs.html" title="org.apache.calcite.rex中的枚举">RexUnknownAs</a></td>
<td class="colLast">
<div class="block">Policy for whether a simplified expression may instead return another
value.</div>
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</tr>
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<h2 title="程序包org.apache.calcite.rex的说明">程序包org.apache.calcite.rex的说明</h2>
<div class="block">Provides a language for representing row-expressions.
<h2>Life-cycle</h2>
<p>A <a href="../../../../org/apache/calcite/sql2rel/SqlToRelConverter.html" title="org.apache.calcite.sql2rel中的类"><code>SqlToRelConverter</code></a> converts a SQL
parse tree consisting of <a href="../../../../org/apache/calcite/sql/SqlNode.html" title="org.apache.calcite.sql中的类"><code>SqlNode</code></a> objects into
a relational expression (<a href="../../../../org/apache/calcite/rel/RelNode.html" title="org.apache.calcite.rel中的接口"><code>RelNode</code></a>). Several
kinds of nodes in this tree have row expressions
(<a href="../../../../org/apache/calcite/rex/RexNode.html" title="org.apache.calcite.rex中的类"><code>RexNode</code></a>).</p>
<p>After the relational expression has been optimized, a
<a href="../../../../org/apache/calcite/adapter/enumerable/JavaRelImplementor.html" title="org.apache.calcite.adapter.enumerable中的类"><code>JavaRelImplementor</code></a> converts it
into to a plan. If the plan is a Java parse tree, row-expressions are
translated into equivalent Java expressions.</p>
<h2>Expressions</h2>
<p>Every row-expression has a type. (Compare with
<a href="../../../../org/apache/calcite/sql/SqlNode.html" title="org.apache.calcite.sql中的类"><code>SqlNode</code></a>, which is created before validation,
and therefore types may not be available.)</p>
<p>Every node in the parse tree is a <a href="../../../../org/apache/calcite/rex/RexNode.html" title="org.apache.calcite.rex中的类"><code>RexNode</code></a>.
Sub-types are:</p>
<ul>
<li><a href="../../../../org/apache/calcite/rex/RexLiteral.html" title="org.apache.calcite.rex中的类"><code>RexLiteral</code></a> represents a boolean,
numeric, string, or date constant, or the value <code>NULL</code>.
</li>
<li><a href="../../../../org/apache/calcite/rex/RexVariable.html" title="org.apache.calcite.rex中的类"><code>RexVariable</code></a> represents a leaf of the
tree. It has sub-types:
<ul>
<li><a href="../../../../org/apache/calcite/rex/RexCorrelVariable.html" title="org.apache.calcite.rex中的类"><code>RexCorrelVariable</code></a> is a
correlating variable for nested-loop joins
</li>
<li><a href="../../../../org/apache/calcite/rex/RexInputRef.html" title="org.apache.calcite.rex中的类"><code>RexInputRef</code></a> refers to a field
of an input relational expression
</li>
<li><a href="../../../../org/apache/calcite/rex/RexCall.html" title="org.apache.calcite.rex中的类"><code>RexCall</code></a> is a call to an
operator or function. By means of special operators, we can
use this construct to represent virtually every non-leaf node
in the tree.
</li>
<li><a href="../../../../org/apache/calcite/rex/RexRangeRef.html" title="org.apache.calcite.rex中的类"><code>RexRangeRef</code></a> refers to a
collection of contiguous fields from an input relational
expression. It usually exists only during translation.
</li>
</ul>
</li>
</ul>
<p>Expressions are generally
created using a <a href="../../../../org/apache/calcite/rex/RexBuilder.html" title="org.apache.calcite.rex中的类"><code>RexBuilder</code></a> factory.</p>
<h2>Related packages</h2>
<ul>
<li><code>org.apache.calcite.sql</code> SQL object model</li>
<li><code>org.apache.calcite.plan</code> Core classes, including
<a href="../../../../org/apache/calcite/rel/type/RelDataType.html" title="org.apache.calcite.rel.type中的接口"><code>RelDataType</code></a> and
<a href="../../../../org/apache/calcite/rel/type/RelDataTypeFactory.html" title="org.apache.calcite.rel.type中的接口"><code>RelDataTypeFactory</code></a>.</li>
</ul></div>
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