| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| package org.apache.empire.db.expr.join; |
| |
| import org.apache.empire.db.DBColumn; |
| import org.apache.empire.db.DBColumnExpr; |
| import org.apache.empire.db.DBCommand; |
| import org.apache.empire.db.DBExpr; |
| import org.apache.empire.db.DBJoinType; |
| import org.apache.empire.db.DBRowSet; |
| |
| /** |
| * This class is used for building a join expression of an SQL statement. |
| * <P> |
| * There is no need to explicitly create instances of this class.<BR> |
| * Instead use @link {@link org.apache.empire.db.DBCommand#join(DBColumnExpr, DBColumn, DBJoinType)} |
| * <P> |
| * |
| */ |
| public abstract class DBJoinExpr extends DBExpr |
| { |
| // *Deprecated* private static final long serialVersionUID = 1L; |
| |
| protected DBJoinType type; |
| |
| /** |
| * Constructs a new DBJoinExpr object initialize this object with |
| * the left and right column and the data type of the join |
| * expression. |
| * |
| * @param left left value |
| * @param right right value |
| * @param type data type (JOIN_INNER, JOIN_LEFT or JOIN_RIGHT) |
| */ |
| protected DBJoinExpr(DBJoinType type) |
| { |
| this.type = type; |
| } |
| |
| /** |
| * returns the join type for this join |
| */ |
| public DBJoinType getType() |
| { |
| return type; |
| } |
| |
| /** |
| * alters the join type for this join |
| */ |
| public void setType(DBJoinType type) |
| { |
| this.type = type; |
| } |
| |
| /** |
| * returns the RowSet on the left of the join |
| */ |
| public abstract DBRowSet getLeftTable(); |
| |
| /** |
| * returns the RowSet on the right of the join |
| */ |
| public abstract DBRowSet getRightTable(); |
| |
| /** |
| * returns true if this join is using the given table or view or false otherwise |
| */ |
| public abstract boolean isJoinOn(DBRowSet rowset); |
| |
| /** |
| * returns true if this join is using the given column or false otherwise |
| */ |
| public abstract boolean isJoinOn(DBColumn column); |
| |
| /** |
| * Returns the left table name if the data type= JOIN_LEFT and returns |
| * the right table if the data type= JOIN_RIGHT. If the |
| * data type = JOIN_INNER the return value is null. |
| * |
| * @return the current DBDatabase object |
| */ |
| public abstract DBRowSet getOuterTable(); |
| |
| /** |
| * Returns the subquery Params |
| * Valid only directly after addSQL() has been called! |
| * @param which: both (==0) | left (<=0) | right (>=0) |
| * @return the subquery params; |
| */ |
| // public abstract Object[] getSubqueryParams(int which); |
| |
| /** |
| * This function swaps the left and the right statements of the join expression. |
| */ |
| public abstract void reverse(); |
| |
| /** |
| * Copy Command |
| * @param cmd |
| */ |
| public abstract DBJoinExpr copy(DBCommand newCmd); |
| |
| } |