# JoinCondition

Defines a join condition.

### Description

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"

### See Also

## joinType

The join type.

### Description

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

### See Also

## joinOperator

The comparator of the condition.

### Description

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

### See Also

## leftDataSet

The name of left data set of the condition.

### Description

The name of left data set of the condition.

### See Also

## rightDataSet

The name of right data set of the condition.

### Description

The name of right data set of the condition.

### See Also

## leftExpression

The left expression of the condition.

### Description

The left expression of the condition.

### See Also

## rightExpression

The right expression of the condition.

### Description

The right expression of the condition.

### See Also