Setting sort or merge criteria

To set sort or merge criteria, define the keys on which the operation is to be performed.

About this task

Do these steps:

Procedure

  1. In the record description of the files to be sorted or merged, define the key or keys.

    Restriction: A key cannot be variably located.

  2. In the SORT or MERGE statement, specify the key fields to be used for sequencing by coding the ASCENDING or DESCENDING KEY phrase, or both. When you code more than one key, some can be ascending, and some descending.

    Specify the names of the keys in decreasing order of significance. The leftmost key is the primary key. The next key is the secondary key, and so on.

Results

SORT and MERGE keys can be of class alphabetic, alphanumeric, national (if the compiler option NCOLLSEQ(BIN) is in effect), or numeric (but not numeric of USAGE NATIONAL). If it has USAGE NATIONAL, a key can be of category national or can be a national-edited or numeric-edited data item. A key cannot be a national decimal data item or a national floating-point data item.

The collation order for national keys is determined by the binary order of the keys. If you specify a national data item as a key, any COLLATING SEQUENCE phrase in the SORT or MERGE statement does not apply to that key.

You can mix SORT and MERGE statements in the same COBOL program. A program can perform any number of sort or merge operations. However, one operation must end before another can begin.

Related references   
NCOLLSEQ
  
SORT statement (COBOL for Linux® on x86 Language Reference)  
MERGE statement (COBOL for Linux on x86 Language Reference)