Expressions are complex items in an SQL statement. Expressions can involve columns from different tables, functions, constants, parameters, mathematical operators, or string operators. They are typically used to form aggregate expressions or perform conditional selects.
You can begin creating an expression in the SQL Statement Builder by right-clicking a column in the Graphic Design area and selecting Add Select Item from the context menu. The Expression wizard shown below appears and allows you to build an expression. The options in the wizard are available based on whether they would contribute to correct SQL syntax.
As you add items to an expression, the expression appears in the text area at the bottom of the wizard. You can back up and go forward through the building process. At each step, the applicable option buttons are available to ensure the correct syntax for an SQL expression. When you are satisfied with the expression you have built, select End Expression, and click Finish. The expression is added to the SQL statement.