Question

如果我有4个表（Army, Navy, Air Force, Marines），则所有表都有serial number作为主键，name。我有一个operation表，其中op_num为主键，op_name。我还有一个表operation member，它将操作表与其他4个表相关联，如何编写单个SQL语句，返回隐蔽操作“沙漠风暴”的成员名称（无论服务分支如何） '使用Microsoft T-SQL语法？

Answer 1

鉴于您的关联表看起来像这样

Operation_Member (op_num, ser_num)

以下查询应返回所需的结果：

SELECT Soldier.Name FROM Operation_Member
INNER JOIN Operation
    ON Operation.op_num = Operation_Member.op_num
INNER JOIN
(
    SELECT ser_num, name FROM Army
    UNION ALL
    SELECT ser_num, name FROM Navy
    UNION ALL
    SELECT ser_num, name FROM Air_Force
    UNION ALL
    SELECT ser_num, name FROM Marines
) Soldier
    ON Soldier.ser_num = Operation_Member.ser_num
WHERE Operation.op_name = 'Desert Storm'

SQL Server中的关联表

1 个答案: