Join Logical Files in DDS

Join logical files combine different fields from more than one physical file into a single record. You must specify the JFILE keyword at the record level for join logical files.

Specify the entries in the following order to define a join logical file:

  1. File-level entries (optional)
  2. Record-level entries
  3. Join-level entries
  4. Field-level entries
  5. Key field-level entries (optional)
  6. Select/omit-field level entries (optional)

Because only one record format is allowed in a join logical file, specify these entries only once.

Figure 2 shows a join logical file coding example.

Figure 2. Join Logical File Coding Example

|...+....1....+....2....+....3....+....4....+....5....+....6....+....7....+....8
00010A* Joins fields from two physical files into one record format
00020A          R RECORD1                   JFILE(PF1 PF2)
00030A          J                           JOIN(PF1 PF2)
00040A                                      JFLD(NAME NAME)
00050A            NAME                      JREF(1)
00060A            ADDR
00070A            PHONE
     A

You can find an explanation of file-, record-, join-, field-, key field-, and select/omit field-levels in Introduction to DDS Reference.

You can find the syntax rules for specifying DDS keywords in DDS Syntax Rules.