Receiving Records Using File Qualifiers

To join records from several iSeries, eServer™ i5, or System i5® files, fields of the same type must be joined.

For example, the part number fields in the INVENTORY and SUPPLIERS files can have the same name PARTNO. To specify the desired PARTNO fields, you must specify which file contains those fields. To do so, file qualifiers are used.

A file qualifier is the character T (uppercase or lowercase) followed by a one- or two-digit number. Use a comma to delimit the file qualifier and field name. In the previous example, prefix T1. and T2. to the PARTNO field names. T1. indicates the first file of FROM, while T2. indicates the second.

To obtain the same information as in the previous example, specify:
Library/File (Member) SUPPLIERS, INVENTORY
JOIN BY T1.PARTNO = T2.PARTNO
SELECT T1.PARTNO, DESCRIPTION, PRICE
WHERE SUPPNO = 51
ORDER BY T1.PARTNO

T1.PARTNO indicates the PARTNO fields in the SUPPLIERS file, while T2.PARTNO indicates the PARTNO fields in the INVENTORY file.

Qualifiers are not needed for the names of the DESCRIPTION, PRICE, and SUPPNO fields, because they exist in one file only. However, the user can specify the following qualifiers for clarity:
T2.DESCRIPTION, T1.PRICE, T1.SUPPNO

The following examples of joining several iSeries, eServer i5, or System i5 files describe more sophisticated techniques. You should now be familiar with the basics of how to join two files. For a more detailed explanation, refer to the following sections.