SQL Server/T-SQL Tutorial/System Settings/ANSI NULLS

SET ANSI_NULLS ON/OFF

3> CREATE TABLE titles(
4>    title_id       varchar(20),
5>    title          varchar(80)       NOT NULL,
6>    type           char(12)          NOT NULL,
7>    pub_id         char(4)               NULL,
8>    price          money                 NULL,
9>    advance        money                 NULL,
10>    royalty        int                   NULL,
11>    ytd_sales      int                   NULL,
12>    notes          varchar(200)          NULL,
13>    pubdate        datetime          NOT NULL
14> )
15> GO
1>
2> insert titles values ("1", "Secrets",   "popular_comp", "1389", NULl, $8000.00, 10, 4095,"Note 1","06/12/94")
3> insert titles values ("2", "The",       "business",     "1389", $19.99, $5000.00, 10, 4095,"Note 2","06/12/91")
4> insert titles values ("3", "Emotional", "psychology",   "0736", $7.99,  $4000.00, 10, 3336,"Note 3","06/12/91")
5> insert titles values ("4", "Prolonged", "psychology",   "0736", $19.99, $2000.00, 10, 4072,"Note 4","06/12/91")
6> insert titles values ("5", "With",      "business",     "1389", $11.95, $5000.00, 10, 3876,"Note 5","06/09/91")
7> insert titles values ("6", "Valley",    "mod_cook",     "0877", $19.99, $0.00,    12, 2032,"Note 6","06/09/91")
8> insert titles values ("7", "Any?",      "trad_cook",    "0877", $14.99, $8000.00, 10, 4095,"Note 7","06/12/91")
9> insert titles values ("8", "Fifty",     "trad_cook",    "0877", $11.95, $4000.00, 14, 1509,"Note 8","06/12/91")
10> GO
(1 rows affected)
(1 rows affected)
(1 rows affected)
(1 rows affected)
(1 rows affected)
(1 rows affected)
(1 rows affected)
(1 rows affected)
1>
2> SET ANSI_NULLS OFF
3> GO
1> SELECT * FROM titles WHERE price = NULL
2> GO
title_id             title                                                                            type         pub_id price                 advance               royalty     ytd_sales   notes
                                                                                                                                                                                               pubdate
-------------------- -------------------------------------------------------------------------------- ------------ ------ --------------------- --------------------- ----------- ----------- ----------
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ---------
--------------
1                    Secrets                                                                          popular_comp 1389                    NULL             8000.0000          10        4095 Note 1
                                                                                                                                                                                               1994-06-1
2 00:00:00.000
(1 rows affected)
1>
2> -- Second batch will return no rows
3>
4> SET ANSI_NULLS ON
5> GO
1>
2> SELECT * FROM titles WHERE price = NULL
3> GO
title_id             title                                                                            type         pub_id price                 advance               royalty     ytd_sales   notes
                                                                                                                                                                                               pubdate
-------------------- -------------------------------------------------------------------------------- ------------ ------ --------------------- --------------------- ----------- ----------- ----------
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- ---------
--------------
(0 rows affected)
1>
2> drop table titles;
3> GO