Queries Involving Null Values
1>
2> CREATE TABLE works_on (emp_no INTEGER NOT NULL,
3> project_no CHAR(4) NOT NULL,
4> job CHAR (15) NULL,
5> enter_date DATETIME NULL)
6> GO
1> insert into works_on values (1, 'p1', 'analyst', '1997.10.1')
2> insert into works_on values (1, 'p3', 'manager', '1999.1.1')
3> insert into works_on values (2, 'p2', 'clerk', '1998.2.15')
4> insert into works_on values (2, 'p2', NULL, '1998.6.1')
5> insert into works_on values (3, 'p2', NULL, '1997.12.15')
6> insert into works_on values (4, 'p3', 'analyst', '1998.10.15')
7> insert into works_on values (5, 'p1', 'manager', '1998.4.15')
8> insert into works_on values (6, 'p1', NULL, '1998.8.1')
9> insert into works_on values (7, 'p2', 'clerk', '1999.2.1')
10> insert into works_on values (8, 'p3', 'clerk', '1997.11.15')
11> insert into works_on values (7, 'p1', 'clerk', '1998.1.4')
12> 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 rows affected)
(1 rows affected)
(1 rows affected)
1>
2> -- Queries Involving Null Values
3>
4> SELECT emp_no, project_no FROM works_on WHERE project_no = 'p2' AND job IS NULL
5> GO
emp_no project_no
----------- ----------
2 p2
3 p2
(2 rows affected)
1> drop table works_on
2> GO
1>
2>
Related examples in the same category