T-SQL 如何从一列中选择没有重复值的行？
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T-SQL How to select rows without duplicate values from one column?
提问by Tony
I have a table with 2 columns ID, ID_PROJ_CSR
我有一个有 2 列的表格 ID, ID_PROJ_CSR
The content of that table is:
该表的内容是：
ID ID_PROJ_CSR
------------------
747 222 <
785 102
786 222 <
787 223
788 224
I want to select the ID, but if any value from ID_PROJ_CSR is a duplicate, I need to select any ID of the rows that contains that duplicate value (in that example, select ID 747OR 786
我想选择 ID，但如果 ID_PROJ_CSR 中的任何值是重复的，我需要选择包含该重复值的行的任何 ID（在该示例中，选择 ID 747OR 786
I try:
我尝试：
SELECT * FROM my_table tab
WHERE tab.id_proj_csr = (SELECT TOP 1 id_proj_csr
FROM my_table mt
WHERE mt.id_proj_csr = tab.id_proj_csr)
回答by cjk
You need to GROUP BY:
您需要 GROUP BY：
SELECT MAX(ID) as [ID], ID_PROJ_CSR
FROM my_table
GROUP BY ID_PROJ_CSR
回答by Gregory Kaczmarczyk
Here's the case of omitting anything that has a duplicate value, so you'll only get rows that don't have duplicates:
这是省略具有重复值的任何内容的情况，因此您只会获得没有重复值的行：
SELECT *
FROM my_table
GROUP BY ID_PROJ_CSR
HAVING count(ID_PROJ_CSR) = 1;
