Reading by key operation

 

This operation gets the record identified by the key value.

Key operations of equal, equal or after, equal or before, read previous key equal, read next key equal, after, or before can be specified. If a format name is specified, the system searches for a record of the specified key value and record format name. If a format name is not specified, the entire keyed sequence access path is searched for the specified key value. If the key definition for the file includes multiple key fields, a partial key can be specified (you can specify either the number of key fields or the key length to be used). This allows you to do generic key searches. If the program does not specify a number of key fields, the system assumes a default number of key fields. This default varies depending on if a record format name is passed by the program. If a record format name is passed, the default number of key fields is the total number of key fields defined for that format. If a record format name is not passed, the default number of key fields is the maximum number of key fields that are common across all record formats in the access path. The program must supply enough key data to match the number of key fields assumed by the system. (The CHAIN statement in the RPG language and the READ statement in the COBOL language are examples of this operation.)

 

Parent topic:

Reading database records using a keyed sequence access path