sql-server - 获取所有数据左表与右表上的条件（ms sql）

Question

colA colB --------------------------------tab_1
1 AA
2 BB
3 CC
4 DD
5 EE

colA colC-------------------tab_2
1 XX
2 YY
3 ZZ

输出必须 (tab_2.colC != ZZ)

colA colB colC
1 AA XX
2 BB YY
4 DD NULL
5 EE NULL

我用左连接尝试过，但它会返回所有 5 条记录

例如：

select tab_1.colA, tab_1.colB, tab_2.colC
from tab_1
left join tab_2 on tab_1.colA = tab_2.colA and tab_2.colC != 'ZZ'

如果有人可以帮助我，我真的很感激？

score 2 · Accepted Answer

SELECT
T1.colA, T1.colB, T2.olC
FROM tab_1 T1
  LEFT JOIN tab_2 T2
    ON T1.colA = T2.colA
WHERE T2.colC != 'ZZ'
   OR T2.colC IS NULL

score 0 · Accepted Answer

SELECT  a.*, b.ColC
FROM    table1 a
        LEFT JOIN table2 b
            ON a.ColA = b.ColA
WHERE   b.colC <> 'zz' OR b.ColC IS NULL

score 0 · Accepted Answer

SELECT t1.colA, t1.colB, t2.colC
FROM tab_1 t1
LEFT JOIN tab_2 t2
ON tab_1.colA = tab_2.colA
WHERE t2.ColC <> 'ZZ' OR t2.ColC IS NULL

3 回答 3