File and member name

Before you can process data in a database file, you must identify which file and member you want to use with the FILE and MBR parameters.

Normally, you specify the file name and, optionally, the member name in your high-level language program. The system then uses this name when your program requests the file to be opened. To override the file name specified in your program and open a different file, you can use the TOFILE parameter on the Override with Database File (OVRDBF) command. If no member name is specified in your program, the first member of the file (as defined by the creation date and time) is processed.

If the member name cannot be specified in the high-level language program (some high-level languages do not allow a member name), or you want a member other than the first member, you can use an OVRDBF command or an open command (OPNDBF or OPNQRYF) to specify the file and member you want to process (using the FILE and MBR parameters).

To process all the members of a file, use the OVRDBF command with the MBR(*ALL) parameter specified. For example, if FILEX has three members and you want to process all the members, you can specify:

OVRDBF   FILE(FILEX)  MBR(*ALL)

If you specify MBR(*ALL) on the OVRDBF command, your program reads the members in the order they were created. For each member, your program reads the records in keyed or arrival sequence, depending on whether the file is an arrival sequence or keyed sequence file.