Adding a Select/Omit Rule

When a logical file record is to be accessed by a program, the select/omit rules are evaluated sequentially by the database until an expression is found to be true, then the related action (Select or Omit) is taken.

Use the *TRUE keyword to specify the action to be taken after all other Select/Omit statements have been processed. Specify "Select: *TRUE" to direct the database to select any records that do not meet any of the previous Select/Omit rules. Conversely, specify "Omit: *TRUE" to omit any records that do not meet any of the previous Select/Omit rules.

If the *TRUE rule is omitted, the default action is to presume you want all remaining records to be either selected or omitted depending upon the last Select/Omit statement. That is:

  • If the last statement was a Select, the default is to assume "Omit: *TRUE" wherein all records that did not meet the any of the previous Select/Omit rules will be omitted.
  • If the last statement was an Omit, the default is to assume "Select: *TRUE" wherein all records that did not meet the any of the previous Select/Omit rules will be selected.

To Add a Select/Omit Rule to a Logical Format

  1. Open the physical file definition source file in the Database File Definition Designer.
  2. In the details tree view of the designer, select the record format node as shown below with the RCMMASTL1 record format.
  3. Select the Select/Omit tab in the lower right panel to display the select/omit grid as shown below.

  4. Scroll to the bottom of the select/omit grid, if necessary. Select the New Row (the last row of the grid) by clicking on the leftmost column of the row.
  5. Select the rule verb by clicking on the drop-down box in the Verb cell. Change the rule expression from the default "*none" to a logical expression pertaining to the rule. Note that the rule will not be added to the format until you select a verb and enter an expression.

A logical expression consists of a field name, an operator, and a constant. The valid relational operators are: >, >=, <, <=, =, !=,. Refer also to the illustration below comparing AS/400 and DataGate coding of rules.

Illustration:

The Select/Omit Rules below compare the rule implementation in DDS and DataGate.

DDS Example:

       	O PRTDSC COMP(EQ 'HAMMER')
	S UNTPRC COMP(GT PRCLVL)
	ONHAND COMP(LT 10)
	O ALL

The same rules as above coded for DataGate:

	Omit: PRTDSC = 'HAMMER'
	Select: UNTPRC > PRCLVL & ONHAND < 10
	Omit: *TRUE

If the expression is incorrectly constructed, an error may occur when creating the file.

Section summary: