776  Appendix A  n  Lab Exercises

Lab 13.3: Performing Linguistic Sorts

In this exercise, you will create a table and populate it with values that are easily sorted. You will then modify the NLS parameters that affect linguistic sorts and query the table, observing how the NLS-parameter settings modify the sort results. Here are the steps:

1.Create a table for linguistic sorts, and populate it.

2.Verify your session NLS parameters.

3.Query the sort table.

4.Modify the sort parameter.

5.Query the table and observe the differences in the sort results. Here’s an example:

1.Create a table for linguistic sorts, and populate it.

SQL> create table linguistic_sort_test (x number, y varchar2(1)); Table created.

SQL>

insert into linguistic_sort_test values (1,’A’); insert into linguistic_sort_test values (2,’B’); insert into linguistic_sort_test values (3,’C’); insert into linguistic_sort_test values (4,’D’); insert into linguistic_sort_test values (5,’E’); insert into linguistic_sort_test values (6,’F’); insert into linguistic_sort_test values (7,’G’); insert into linguistic_sort_test values (8,’H’); insert into linguistic_sort_test values (9,’I’); insert into linguistic_sort_test values (10,’J’); insert into linguistic_sort_test values (11,’a’); insert into linguistic_sort_test values (12,’b’); insert into linguistic_sort_test values (13,’c’); insert into linguistic_sort_test values (14,’d’); insert into linguistic_sort_test values (15,’e’); insert into linguistic_sort_test values (16,’f’); insert into linguistic_sort_test values (17,’g’); insert into linguistic_sort_test values (18,’h’); insert into linguistic_sort_test values (19,’i’); insert into linguistic_sort_test values (20,’j’); commit;

2.Verify your session NLS parameters.

SQL> select * from nls_session_parameters; PARAMETER VALUE

SQL>

3.Query the sort table. Order by the numeric value as a baseline or control query, and then order by the character column using the default BINARY sort.

SQL> select * from linguistic_sort_test order by x;

X Y

---------- -

778  Appendix A  n  Lab Exercises

8 H

9 I

10J

11a

12b

13c

14d

15e

16f

17g

18h

19i

20j

20 rows selected.

SQL>

SQL> select * from linguistic_sort_test order by y;

X Y

---------- -

18h

19i

20j

20 rows selected.

4.Modify the sort parameter. The default was BINARY; we’ll modify it to EBCDIC to demonstrate the simple difference.

SQL>

SQL> alter session set nls_sort=’EBCDIC’; Session altered.

5.Query the table and observe the differences in the sort results from the previous query.

SQL> select * from linguistic_sort_test order by y;

X Y

---------- -

11a

12b

13c

14d

15e

16f

17g

18h

19i

20j 1 A 2 B 3 C 4 D 5 E 6 F 7 G 8 H 9 I

10 J

20 rows selected.

780  Appendix A  n  Lab Exercises

Notice that the EBCDIC sort placed the lowercase letters at the beginning of the sort because they have a lower EBCDIC value than their uppercase counterparts.

If we now set the NLS_SORT value to ASCII7, you’ll see the same results as BINARY for this simple sort.

SQL> alter session set nls_sort=’ASCII7’;

Session altered.

SQL> select * from linguistic_sort_test order by y;

X Y

---------- -

20 rows selected.

Now if you set the NLS_SORT to CROATIAN, you’ll see something really interesting.

SQL> alter session set nls_sort=’CROATIAN’;

Session altered.

SQL> select * from linguistic_sort_test order by y;

X Y

---------- -

1 A

11a 2 B

12b 3 C

13c 4 D

14d 5 E

15e 6 F

16f 7 G

17g 8 H

18h 9 I

19i

10J

20j

20 rows selected.

SQL>

And when you set NLS_SORT to THAI_M, you’ll see the opposite pattern from the one for CROATIAN.

SQL> alter session set nls_sort=’THAI_M’;

Session altered.

SQL> select * from linguistic_sort_test order by y;

782  Appendix A  n  Lab Exercises

X Y

---------- -

11a 1 A

12b 2 B

13c 3 C

14d 4 D

15e 5 E

16f 6 F

17g 7 G

18h 8 H

19i 9 I

20j

10J

20 rows selected.

SQL>

Remember that setting NLS_LANGUAGE will override the NLS_SORT setting, but NLS_SORT can be set to whatever valid setting you choose following a change to NLS_LANGUAGE.