Defines a join condition.

User can define a joint data set which is a data set joined by several data sets on some join conditions, The join condition is whether two expressions,left expression and right expression, satisfy a relationship defined by the join operator which can be equality, less than or greater than. Left expression is an expression of fields from left dataset, right expression is an expression of fields from right dataset.

For example, a condition can be:

       dataSet1 inner join dataSet2 on 2 * column1 = 3 * column2

"column1" is from the data set named "dataSet1", "coloumn2" is from "dataSet2".

This condition is defined by JoinCondition with following members:

	joinType	=	inner join
	joinOperator	=	eq
	leftDataSet	=	"dataSet1"
	rightDataSet	=	"dataSet2"
	leftExpression	=	"2 * column1"
	rightExpression	=	"3 * column2"

The comparator of the condition: equals, less than or greater than.

The join type: inner join, left out join or right out join.

The name of left data set of the condition.

The left expression of the condition.

The name of right data set of the condition.

The right expression of the condition.