Question

我有以下结构：

TABLE1         TABLE2
id_worker_main  id_worker
id_worker_sub   name_worker

我需要选择为id_worker_main和id_worker_sub获取name_worker，但我不能。以下查询返回两次相同的名称。

SELECT t2.name_worker as main, t2.name_worker as sub 
FROM table1 
INNER JOIN table2 ON t1.id_worker_main = t2.id_worker AND t1.id_worker_sub = t2.id_worker

Answer 1

您必须两次加入同一张桌子。只需为每个联接使用不同的别名

<强> Sql Fiddle Demo

有了这个工人

INSERT INTO Table2
    ([id_worker], [name_worker])
VALUES
    (1, 'Juan'),
    (2, 'Angela'),
    (3, 'Peter');

这种关系

INSERT INTO Table1
    ([id_worker_main], [id_worker_sub])
VALUES
    (1, 2),
    (2, 3),
    (1, 3);

使用此查询

SELECT A.name_worker MAINWORKER, B.name_worker SUBWORKER
FROM Table1 T1 
Inner join Table2 A
   ON T1.id_worker_main = A.id_worker
Inner join Table2 B
   ON T1.id_worker_sub = B.id_worker

<强>输出

| MAINWORKER | SUBWORKER |
|------------|-----------|
|       Juan |    Angela |
|     Angela |     Peter |
|       Juan |     Peter |

Answer 2

如果我正确理解您的问题，您可以多次加入table2

SELECT t21.name_worker as main, t22.name_worker as sub
FROM table1 t1
JOIN table2 t21 on t21.id_worker = t1.id_worker_main
JOIN table2 t22 on t22.id_worker = t1.id_worker_sub

SQL Server选择重复列值

2 个答案: