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[英]MYSQL - How to select a row with a certain value, but only if it appears once?
[英]How to select the same value only once in MysQL?
我有這張桌子:
-------
id a b
-------
1 1 1
2 1 5
3 1 1
4 1 1
5 1 6
我該如何選擇?
-------
id a b
-------
1 1 1
2 1 5
5 1 6
嘗試:
SELECT MIN(id), a, b FROM table GROUP BY a, b
SELECT MIN(id), a, b
FROM table
GROUP BY a,b
select id, a, b from table
where id in (1,2,5)
select min(id), a,b from foo group by a,b;
下面的示例將為您提供所需的信息,但是我不確定如果min ID是關鍵,那么min ID是否有用。
SELECT MIN(id), a, b
FROM table
GROUP BY a,b
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