Question

如果我有一个包含

列的表格

ID1 ID2 VAL1 VAL2

ID1，ID2作为主键索引。

如何为特定的ID1，ID2值执行任何SQL语句？

示例：我的记录表有PK（1,1）（1,2）（2,4）（2,1）（3,1）（3,2）（3,5）

我想只选择带（1,1）（1,2）（3,5）（3,2）

的记录

带

的SELECT查询

SELECT * FROM tbl1 WHERE ID1 IN（1,3）AND ID2 IN（1,2,5）

将产生不希望的结果：（3,1）。那么最好的方法是什么？

我正在寻找SQL的总体答案，但如果它依赖于DBMS，我想知道如何在PostgreSQL和MySQL中这样做。

Answer 1

MySQL和PostgreSQL都支持IN中的元组，如下所示。

SELECT * 
FROM tbl1
WHERE (ID1,ID2) IN ((1,1) (1,2) (2,4) (2,1) (3,1) (3,2) (3,5));

Answer 2

您可以使用and和or：

执行此操作

SELECT  * 
FROM    tbl1
WHERE   ID1 = 1 AND ID2 = 1 OR
        ID1 = 1 AND ID2 = 2 OR
        ID1 = 3 AND ID2 = 5 OR
        ID1 = 2 AND ID2 = 2

Answer 3

这可能是您所要求的最紧凑的方式：

SELECT *
FROM tbl1
WHERE (ID1 = 1 AND (ID2 = 1 OR ID2 = 2))
   OR (ID1 = 3 AND (ID2 = 5 OR ID2 = 2));

Answer 4

SELECT * FROM tbl1 WHERE ID1 = 1 AND ID2 IN (1,2)
UNION
SELECT * FROM tbl1 WHERE ID1 = 3 AND ID2 IN (5,2)

OR

SELECT * FROM tbl1 WHERE (ID1 = 1 AND ID2 IN (1,2)) OR (ID1 = 3 AND ID2 IN (5,2))

Answer 5

您也可以尝试

SELECT
   *
FROM
  tbl1
  JOIN
  (
    SELECT 1 AS ID1, 1 AS ID2
    UNION ALL
    SELECT 1 AS ID1, 2 AS ID2
    UNION ALL
    SELECT 2 AS ID1, 4 AS ID2
    UNION ALL
    SELECT 2 AS ID1, 1 AS ID2
    UNION ALL
    SELECT 3 AS ID1, 1 AS ID2
    UNION ALL
    SELECT 3 AS ID1, 2 AS ID2
    UNION ALL
    SELECT 3 AS ID1, 5 AS ID2
  ) as keylist ON tbl1.ID1 = keylist.ID1 AND tbl1.ID2 = keylist.ID2

如何在具有复合键列表的表上执行SELECT？

5 个答案: