Using the JOIN Command to Process Multiple Files

You can JOIN ADABAS databases defined to FOCUS to other ADABAS databases, to FOCUS files, or to any other fully joinable, FOCUS-readable databases. Each JOIN creates a parent-child relationship. The parent field is called the host or from field. The child field is called the cross-referenced or to field. See the FOCUS for IBM Mainframe User's Manual for more information about the JOIN command.

You can JOIN to ADABAS databases if the cross-referenced field is one of the following:"

• A descriptor field.
• A superdescriptor defined with TYPE=SPR or NOP in the Access File.
• A subdescriptor defined with TYPE=NOP in the Access File.

In every case, in the Access File, the cross-referenced segment must specify ACCESS=ADBS.

If CALLTYPE=RL is specified for the cross-referenced segment, the host field can be joined to the high-order portion of a descriptor, superdescriptor, or subdescriptor.

When an ADABAS file is the host file, the host field is one of the following:

• A non-recurring field (ACCESS=ADBS).
• A field in a periodic group (ACCESS=PE).
• A multi-value field (ACCESS=MU).

The ADABAS Interface also supports DEFINE-based JOINs. Up to 16 JOINs can be in effect at one time.

Multi-field JOIN and Short-to-long JOIN Capability

For a multi-field JOIN, the number of fields used in the JOIN must be the same for both the host and the cross-referenced files. The cross-referenced fields must describe the left-most portion of a superdescriptor defined to FOCUS using the GROUP attribute. For example:

JOIN FLDA AND FLDB IN ADBS1 TO KEY1 AND KEY2 IN ADBS2 AS J1

For the short-to-long JOIN, the cross-referenced field must be either a descriptor, subdescriptor, or superdescriptor, or a field that describes the left-most portion of a GROUP superdescriptor.