SELECT Statement

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

(4) Access key field name

ACCESS PATH Predefined Field

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

• •     Next, use the SELECT statement to set the desired path IF   --- OPTION EQ USER 1

• •     Ignore these buttons if pushed in ADD mode IF   --- MODE EQ ADD

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

***** SELECT   *** ********************** *** ***************
(1)            (2) (3)                    (4) (5)

(1) T/F execution conditions 
(2) Application ID
(3) File Name, field name, or predefined field
(4) Occurrence (constant/index)
(5) Data item type (FIELD, RECORD, DEFAULT FIELD, DEFAULT RECORD, ORIGINAL FIELD, ORIGINAL RECORD)

SELECT ILF Statement

SELECT

      SELECT  AAA FILENAME                        KEY IS  _____________________________

One reasonable use for the SELECT statement would be to facilitate access path switching by users, without them having to use F3 (SELECT ACCESS PATH), and perhaps in that way limiting which keys they can select. 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. It would seem that a valuable use would be to redisplay a scrolling screen using an alternate key, and to do so, the above defined PUSH and POP statements come in very handy. Here's an example:

The file is called 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 one line of code to Pre-Display:

      POP     --- OPTION                    FIELD

Also related to this new statement is a new Pre-Defined Field called --- ACCESS PATH. As one might assume, the 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).

Limitations:

Comments:

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-- SteveFrizzell - 01 Oct 2008