IMAGE/SQL Field Lists

Field List Options in IMAGE/SQL

The Field List is a parameter of the DBGET, DBPUT and DBUPDATE IMAGE/SQL intrinsics. It specifies which fields of a dataset to process. By asking for only the fields you need, you make the program more independent of database changes. This is the most flexible--and slowest--form of field list. A typical value is a character string that has a series of fieldnames, separated by commas, ending with a semicolon:

CUST-NUM,CUST-NAME,CUST-PHONE;.

A slightly faster list is a series of item numbers, but if you hard-code item numbers in a program, you're asking for maintenance problems. The "@" (all) field list is much less general, and much faster. It returns the entire dataset entry in the order defined in the schema. The drawback to "@" is that you must recompile the program whenever the dataset format changes. Even faster than "@" is the "*" field list. "*" says to use the same field list as on the last call for the same dataset. "*" after "@" is faster than "@", and "*" after a list of names is even faster. And the simplest form of field list is "0" for the null list.