Displaying Joined Structures

How to:

When you join two data sources together, they are subsequently treated as one logical structure. This structure results from appending the structure of the cross-referenced file to the structure of the host file. The segment in the cross-referenced file containing the shared value field becomes the child of the segment in the host file with the shared value field.

Syntax: How to Display a Joined Structure

To display the joined structure, issue the following command: 

CHECK FILE hostfile PICTURE

where:

hostfile
Is the name of the host file.

Example: Displaying a Joined Structure

Notice that the segments belonging to the host file appear as regular segments outlined by asterisks. The segments belonging to the cross-referenced file appear as virtual segments outlined by dots. The segments of the cross-referenced file are also labeled with the cross-referenced file name below each segment. 

JOIN PIN IN EMPDATA TO PIN IN SALHIST
CHECK FILE EMPDATA PICTURE
0 NUMBER OF ERRORS=     0
  NUMBER OF SEGMENTS=   2  ( REAL=    1  VIRTUAL=   1 )
  NUMBER OF FIELDS=    14  INDEXES=   1  FILES=     2
  NUMBER OF DEFINES=    1
  TOTAL LENGTH OF ALL FIELDS=  132
1SECTION 01.01
              STRUCTURE OF FOCUS    FILE EMPDATA  ON 03/05/01 AT 12.22.49
          EMPDATA
  01      S1
 **************
 *PIN         **I
 *LASTNAME    **
 *FIRSTNAME   **
 *MIDINITIAL  **
 *            **
 ***************
  **************
        I
        I
        I
        I SLHISTRY
  02    I KU
 ..............
 :PIN         :K
 :EFFECTDATE  :
 :OLDSALARY   :
 :            :
 :            :
 :............:
  JOINED  SALHIST

The top segment of the cross-referenced file structure is the one containing the shared-value field. If this segment is not the root segment, the cross-referenced file structure is inverted, as in an alternate file view.

The cross-referenced file segment types in the joined structure are the following:

  • In unique join structures, the top cross-referenced file segment has the segment type KU. Its unique child segments have segment type KLU. Non-unique child segments have segment type KL.
  • In non-unique join structures, the top cross-referenced file segment has the segment type KM. Its unique child segments have segment type KLU. Non-unique child segments have segment type KL.

The host file structure remains unchanged. The cross-referenced file may still be used independently.

Syntax: How to List Joined Structures

To display a list of joined data sources, issue the following command: 

? JOIN

This displays every JOIN command currently in effect. For example: 

  JOINS CURRENTLY ACTIVE
 
HOST                        CROSSREFERENCE
FIELD      FILE      TAG    FIELD      FILE     TAG    AS       ALL  WH
-----      ----      ---    -----      ----     ---    --       ---  --
JOBCODE    EMPLOYEE         JOBCODE    JOBFILE                   N    N

If the joined structure has no join name, the AS phrase is omitted. If two data sources are joined by multiple JOIN commands, only the first command you issued is displayed. The N in the WH column indicates that the join is not conditional. A Y indicates that the join is conditional.