Freehand Joins in Information Designer

In many situations, a join can be defined using one of the operators in the Condition drop-down list. However, it may sometimes be desirable to use more complex conditions, such as:

• %1 = 2 * %2 (mathematical calculation prior to comparison)

• %1 = %3 AND %4 = %2 (an intermediate table used to set up the join)

In the latter case, it is important to select which tables to join - the tables in which %1 and %2 occur. The other columns included in the join condition, %3 and %4, are found in an intermediate table. No join is created between this table and the other two.

Example:

In the following tables, we want to create a join that links T1 and T3. In this way, we will be able to query the database for, say, the address of the person who earns 1400. To achieve this, T2 is used as intermediate table. The tables T1 and T3 should be selected from the Target tables' drop-down lists (see Creating a Join). The join, again, is defined as:

%1 = %3 AND %4 = %2

See also:

Creating a Join

Joins Overview