SELECT ILF Statement

SELECT Statement

The SELECT statement allows the access path of in input process to be changed dynamically. The structure of the statement is: 

***** SELECT   *** ********                      KEY IS  **********************
(1)            (2) (3)                                   (4)

(1) T/F execution conditions 
(2) Application ID
(3) File name
(4) Access key field name 

The application and file name must be specified and must be the same as the Process Control File (PCF) of the input process.

The Access Key Field name must be a valid key for the specified file.  SCAN is available during entry of the key field name and only defined keys are presented as choices.

Execution of a SELECT statement effectively instructs the input process to use the specified access path (key) the next time that the input process enters KEY ENTRY.  At that point, the user will be prompted to enter a key value for the specified access path.

ACCESS PATH Predefined Field

Also related to the SELECT statement is a Pre-Defined Field called --- ACCESS PATH. This field contains the value of the current access path for the Process Control File. The field may be viewed, but not changed via ILF code (that is to say, an ILF statement to SET --- ACCESS PATH to a specified value will be ignored).

Examples:

One reasonable use for the SELECT statement is be to facilitate access path switching by users of a scrolling input process. For example, an input screen could be designed to include three buttons that the user could use to select the desired access path for the input process. Note that the SELECT statement does not force KEY ENTRY phase, so, without further coding, a user not in KEY ENTRY would see no immediate change in view.

In the following example, the file name is TEST42. The primary key is TEST42 ID NO.. Alternate keys are defined as TEST42 CATEGORY and TEST42 REGION. The screen has three buttons defined, linked to User Option 1, 2, and 3. The Option Intercept Event Point contains the following code:

      *        First, we disable the SELECT ACCESS PATH option (F3)
      IF       --- OPTION                    EQ     SELECT ACCESS PATH
T     SET      --- OPTION                     =
      *        Next, use the SELECT statement to set the desired path
      IF       --- OPTION                    EQ     USER 1
T     SELECT   TST TEST42                       KEY IS  TEST42 CATEGORY
F     IF       --- OPTION                    EQ     USER 2
FT    SELECT   TST TEST42                       KEY IS  TEST42 REGION
FF    IF       --- OPTION                    EQ     USER 3
FFT   SELECT   TST TEST42                       KEY IS  TEST42 ID NO
FFF   END
      *        Ignore these buttons if pushed in ADD mode
      IF       --- MODE                      EQ     ADD
T     END
      *        Now, push the options into the stack to switch into KEY ENTRY
      *        and redisplay the records (remember, last in, first out)
      SET      --- OPTION                     =     RETURN
      PUSH     --- OPTION                    FIELD
      *
      IF       --- MODE                      EQ     DELETE
T     SET      --- OPTION                    =      DELETE MODE
F     IF       --- MODE                      EQ     CHANGE
FT    SET      --- OPTION                    =      CHANGE MODE
FF    SET      --- OPTION                    =      INQUIRE MODE
      PUSH     --- OPTION                    FIELD

Finally, just add three lines of code to the beginning of the Pre-Display event point:

      IF       --- INTERACTIVE PHASE          NE     DATA SCROLL
T     POP      --- OPTION                    FIELD
T     END

Comments:

-- SteveFrizzell - 01 Oct 2008