将多个表连接到一个表

Question

我有表A，B，C，我想将这些表连接成一个表但是表A没有表B和表C的链接字段。表B和表C有。

Answer 1

使用UNION ALL，您必须将列命名为相同：

SELECT COLA1 AS [COMMON_COL1], COLA2 AS [COMMON_COL2]
FROM A
UNION ALL
SELECT COLB1 AS [COMMON_COL1], COLB2 AS [COMMON_COL2]
FROM B
UNION ALL
SELECT COLC1 AS [COMMON_COL1], COLC2 AS [COMMON_COL2]
FROM C
ORDER BY [COMMON_COL1]