Right-click a column in the graphic design area of the screen and select Add Select Item from the context menu. The Expression Wizard appears.
Select the column, SQL function, parameter, or constant you want to start the expression with and click the Next button. Your selection appears in the field at the bottom of the wizard.
NOTE: If you select a function of Cast, Convert, DateDiff, or DatePart, an input dialog box will appear that you must select a value from in order to continue creating the expression. For example, if you select Convert, you must select the the data type you want to convert to. If you select DatePart, you must select the part of the date you want to use in the expression.
Continue making selections from the wizard and follow its instructions until you complete the expression and the Finish button appears.
Click the Finish button to add the expression to the current statement.
For more information on expressions, see the Building Expressions section.