Valid Keys for a Record or File

For a keyed-sequence access path, you can define one or more fields in the DDS to be used as the key fields for a record format. All record types in a file do not have to have the same key fields. For example, an order header record can have the ORDER field defined as the key field, and the order detail records can have the ORDER and LINE fields defined as the key fields.

The key for a file is determined by the valid keys for the record types in that file. The file’s key is determined in the following manner:

• If all record types in a file have the same number of key fields defined in the DDS that are identical in attributes, the key for the file consists of all fields in the key for the record types. (The corresponding fields do not have to have the same name.) For example, if the file has three record types and the key for each record type consists of fields A, B, and C, the file’s key consists of fields A, B, and C. That is, the file’s key is the same as the records’ key.
• If all record types in the file do not have the same key fields, the key for the file consists of the key fields common to all record types. For example, a file has three record types and the key fields are defined as follows:
  • REC1 contains key field A.
  • REC2 contains key fields A and B.
  • REC3 contains key fields A, B, and C.

  The file’s key is field A–the key field common to all record types.

• If no key field is common to all record types, there is no key for the file.

In an ILE RPG program, you can specify a search argument on certain file operation codes to identify the record you want to process. The ILE RPG program compares the search argument with the key of the file or record, and processes the specified operation on the record whose key matches the search argument.