选择具有另一个表的单个非唯一值的一列的唯一值

Question

我有下表，我必须从中获取结果行：

SAMPLE TABLE

id  |  Course
----+----------------------
39  |   B.Sc.-IT-6
40  |   B.Sc.-CS/DCS-2
41  |   B.Sc.-CS-3
42  |   B.Sc.-CS-4
43  |   B.Sc.-CS-5
44  |   B.Sc.-CS-6
45  |   MBA-3
46  |   MBA-3
47  |   MBA-3
48  |   MBA-3
49  |   MBA-3
50  |   MBA-3
51  |   MBA-3
52  |   MBA-3
53  |   MBA-4
54  |   MBA-4
55  |   MBA-4
56  |   MBA-4
57  |   MBA-4
58  |   MBA-4
59  |   BA-1
60  |   BA-2

我想检索只显示一次的重复值，其值为第一个值，如

预期输出

id  |   course
----+---------------------
39  |   B.Sc.-IT-6
40  |   B.Sc.-CS/DCS-2
41  |   B.Sc.-CS-3
42  |   B.Sc.-CS-4
43  |   B.Sc.-CS-5
44  |   B.Sc.-CS-6
45  |   MBA-3
53  |   MBA-4

Answer 1

试试这个。

<强> QUERY

SELECT MIN(id) AS 'ID',column_name 
FROM test 
GROUP BY column_name
ORDER BY id;

<强> FIND SQLFIDDLE HERE