com.simba.dsi.ext.aetree
Class AEJoin

java.lang.Object
  extended by com.simba.dsi.CppClassWrapper
      extended by com.simba.dsi.ext.aetree.AENode
          extended by com.simba.dsi.ext.aetree.AEQueryOperation
              extended by com.simba.dsi.ext.aetree.AERelationalExpr
                  extended by com.simba.dsi.ext.aetree.AEBinaryRelationalExpr
                      extended by com.simba.dsi.ext.aetree.AEJoin

public final class AEJoin
extends AEBinaryRelationalExpr

This class models the derived join relational operation: Join(R1, R2, Cond), where "Cond" is the join condition.

The following two semantically identical SQL queries can be translated to an AEJoin operation directly.

 SELECT A.*, B.* FROM A,B WHERE cond
 
 A JOIN B ON cond
 
The following two queries, however, cannot be translated to an AEJoin operation directly. They can be translated to a join following a project operation. That is, pa(A f B), where j represents the implicit joining condition: A.c1 = B.c1 AND A.c2 = B.c2 AND ... . That is, to translate such a join construct, the translator needs to first figure out the common columns in the two tables.
 A JOIN B USING (common_column_list)
 
 A NATURAL JOIN B
 
NOTE: The following joins are not currently supported by the parser,


Constructor Summary
AEJoin(long objRef, JoinType joinType)
          Constructor.
 
Method Summary
 AEBooleanExpr getJoinCond()
          Retrieves the join condition.
 JoinType getJoinType()
          Retrieves the join type.
 
Methods inherited from class com.simba.dsi.ext.aetree.AEBinaryRelationalExpr
getLeftOperand, getRightOperand
 
Methods inherited from class com.simba.dsi.ext.aetree.AERelationalExpr
isNamed
 
Methods inherited from class com.simba.dsi.ext.aetree.AEQueryOperation
getColumn, getColumnCount
 
Methods inherited from class com.simba.dsi.ext.aetree.AENode
getChild, getChildCount, getNodeType
 
Methods inherited from class com.simba.dsi.CppClassWrapper
getObjRef
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

AEJoin

public AEJoin(long objRef,
              JoinType joinType)
Constructor.

Parameters:
objRef - The corresponding C++ object reference.
joinType - The node type.
Method Detail

getJoinType

public JoinType getJoinType()
Retrieves the join type.

Returns:
The join type.

getJoinCond

public AEBooleanExpr getJoinCond()
Retrieves the join condition.

Returns:
The join condition.


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