If the DataWindow object will contain data from more than one table, you should join the tables on their common columns. If you have selected more than one table, DataWindow Designer joins columns according to whether they have a key relationship:
Columns with a primary/foreign key relationship are joined automatically.
Columns with no key relationship are joined, if possible, based on common column names and types.
DataWindow Designer links joined tables in the Select painter Table Layout view. DataWindow Designer joins can differ depending on the order in which you select the tables, and sometimes the DataWindow Designer best-guess join is incorrect, so you may need to delete a join and manually define a join.
To delete a join:
Click the join operator connecting the tables.
The Join dialog box displays.
Click Delete.
To join tables:
Click the Join button in the PainterBar.
Click the columns on which you want to join the tables.
To create a join other than an equality join, click the join operator in the Table Layout view.
The Join dialog box displays:
Select the join operator you want and click OK.
If your DBMS supports outer joins, outer join options also display in the Join dialog box.
