Click above to get retro games delivered to your door ever month!

   The Expression control can be used on the Query object in two distinct
   modes. Depending on the fact that it is associated or not associated
   to a variable, the system will build the query expression differently. In
   the first case, the control is added to the Get cycle. In the second case,
   the expression is added to the global query expression.

Associated to variable

   When the expression control is associated to a variable, the GET
   variable field in the definition frame must contain the name of the
   variable associated to the control. Key F7 is available for copying a
   variable from the Data Dictionary's symbols.

   In the generated application, the end-user can enter data into the memory
   variable, that will be compared to the value of the expression entered in
   the Expression field. The comparison is made using the operator set in
   the Query expression parameter in the Options environment.

Example:

     
     (Definition frame)
     Expression.........: "TEST.DBF"
     GET picture........: !!!!!!!!!!!!
     SAY picture........: !!!!!!!!!!!!
     Message............: Enter file name
     GET variable.......: cFile
     
     (Options)
     Query expression...: =  Equal to
     

   The above example will add a variable to the get cycle (cFile). The
   contents will then be compared (= Equal to) to "TEST.DBF". The
   Expression field can contain any valid expression, as long as the
   value is of same type as the variable's.

Not associated to variable

   In this case, the expression entered in the Expression field is added
   to the global query expression. Please note, that the result of the
   Expression MUST be logical (True or False).

Example:

     
     (Definition frame)
     Expression.........: DATE()=dDay
     GET picture........:
     SAY picture........:
     Message............:
     GET variable.......: <Empty>
     

   The expression must return a logical result, either True or False.

   In the generated application, the expression is not displayed on the
   object. The programmer can use this method to force an additional
   filtering condition to the query, without having the user to enter the
   necessary values.