[英]How do I select distinct rows where a column may have a number of the same values but all their 2nd columns have the same value?
[英]How can I select rows with all Column value, which have the same values?
SELECT
memId, GROUP_CONCAT(courId)
FROM table_name
GROUP BY memId
假设您已经创建了如下所示的表
CREATE TABLE test (
MemId INTEGER,
CourId VARCHAR (50)
);
并执行如下所示的插入
INSERT INTO test VALUES (1, '2');
INSERT INTO test VALUES (1, '3');
INSERT INTO test VALUES (2, '2');
INSERT INTO test VALUES (3, '1');
INSERT INTO test VALUES (3, '3');
像这样运行查询
SELECT MemId, GROUP_CONCAT( CourId) FROM test GROUP BY MemId
你的结果应该是这样的
| MemId | GROUP_CONCAT( CourId) |
|-------|-----------------------|
| 1 | 2,3 |
| 2 | 2 |
| 3 | 1,3 |
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