Sort sequence and row selection

Sort sequences affect selection of data.

The following SQL statement selects rows with the value 'MGR' in the JOB column: 
SELECT * FROM STAFF WHERE JOB='MGR'

The first table shows how row selection is done with a *HEX sort sequence. The rows that match the row selection criteria for the column JOB are selected exactly as specified in the select statement. Only the uppercase 'MGR' is selected.

Table 1. Result of using the *HEX sort sequence
ID NAME DEPT JOB YEARS SALARY COMM
30 Merenghi 38 MGR 5 17506.75 0

Table 2 shows how row selection is done with a unique-weight sort sequence. The lowercase and uppercase letters are treated as unique. The lowercase 'mgr' is not treated the same as uppercase 'MGR'. Therefore, the lowercase 'mgr' is not selected.

Table 2. Result of using unique-weight sort sequence for the ENU language identifier
ID NAME DEPT JOB YEARS SALARY COMM
30 Merenghi 38 MGR 5 17506.75 0

The following table shows how row selection is done with a shared-weight sort sequence. The rows that match the row selection criteria for the column 'JOB' are selected by treating uppercase letters the same as lowercase letters. Notice that all the values 'mgr', 'Mgr' and 'MGR' are selected.

Table 3. Result of using the shared-weight sort sequence for the ENU language identifier
ID NAME DEPT JOB YEARS SALARY COMM
10 Sanders 20 Mgr 7 18357.50 0
30 Merenghi 38 MGR 5 17506.75 0
50 Hanes 15 Mgr 10 20659.80 0
100 Plotz 42 mgr 6 18352.80 0