问题描述
我相信这对于 t-sql 大师来说会非常简单.
Im sure this will be pretty simple for a t-sql guru.
我从表格中得到以下结果
I have the following result from a table
idMain IdSecondary TextValue 1 1 text1 1 2 text2 2 5 text3 2 6 text5
我只想获得 idMain 的第一次出现.
And I want to obtain the first occurence of the idMain only.
结果应该是这样的.
idMain idSecondary TextValue 1 1 text1 2 5 text3
我怎样才能做到这一点?
How can I achieve this?
推荐答案
您应该能够加入子查询,如下例所示.这假设第一"是指最低的 idSecondary:
You should be able to join with a sub query, as in the following example. This assumes that by "first" you mean the lowest idSecondary:
SELECT t.idMain, sub_t.minSecondary, t.textValue FROM your_table t JOIN (SELECT idMain, MIN(idSecondary) minSecondary FROM your_table GROUP BY idMain) sub_t ON (sub_t.idMain = t.idMain);