DISTINCT clause can be used only once in a SELECT list, precede all column names in that list
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>
7> insert into works_on values (1, 'p1', 'analyst', '1997.10.1')
8> insert into works_on values (1, 'p3', 'manager', '1999.1.1')
9> insert into works_on values (2, 'p2', 'clerk', '1998.2.15')
10> insert into works_on values (2, 'p2', NULL, '1998.6.1')
11> insert into works_on values (3, 'p2', NULL, '1997.12.15')
12> insert into works_on values (4, 'p3', 'analyst', '1998.10.15')
13> insert into works_on values (5, 'p1', 'manager', '1998.4.15')
14> insert into works_on values (6, 'p1', NULL, '1998.8.1')
15> insert into works_on values (7, 'p2', 'clerk', '1999.2.1')
16> insert into works_on values (8, 'p3', 'clerk', '1997.11.15')
17> insert into works_on values (7, 'p1', 'clerk', '1998.1.4')
18>
19> select * from works_on
20> 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)
emp_no project_no job enter_date
----------- ---------- --------------- -----------------------
1 p1 analyst 1997-10-01 00:00:00.000
1 p3 manager 1999-01-01 00:00:00.000
2 p2 clerk 1998-02-15 00:00:00.000
2 p2 NULL 1998-06-01 00:00:00.000
3 p2 NULL 1997-12-15 00:00:00.000
4 p3 analyst 1998-10-15 00:00:00.000
5 p1 manager 1998-04-15 00:00:00.000
6 p1 NULL 1998-08-01 00:00:00.000
7 p2 clerk 1999-02-01 00:00:00.000
8 p3 clerk 1997-11-15 00:00:00.000
7 p1 clerk 1998-01-04 00:00:00.000
(11 rows affected)
1>
2> -- DISTINCT clause can be used only once in a SELECT list, precede all column names in that list.
3>
4> SELECT emp_fname, DISTINCT emp_no FROM works_on WHERE project_no = 'p1' OR project_no = 'p2'
5> GO
Msg 156, Level 15, State 1, Server JAVA2S\SQLEXPRESS, Line 4
Incorrect syntax near the keyword 'DISTINCT'.
1>
2> drop table works_on
3> GO
1>
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