如何在PL/SQL中加入子查询？

Question

我需要在oracle中加入子查询。这不起作用我收到连接操作的语法错误

select s1.key, s1.value, s2.value 
from ((select key, value
        from tbl 
        where id = 1) as s1
join 
    (select key, value
        from tbl 
        where id = 2) as s2
on s1.contract = s2.contract);

Answer 1

您应该在内联视图中选择要加入的字段 (contract)：

SELECT  s1.key, s1.value, s2.value 
FROM    (
        SELECT contract, key, value
        FROM   tbl 
        WHERE  id = 1
        ) as s1
JOIN    (
        SELECT  contract, key, value
        FROM    tbl 
        WHERE   id = 2
        ) as s2
ON     s1.contract = s2.contract

Answer 2

你的括号太多了。

SELECT
  s1.key, 
  s1.value, 
  s2.value 
FROM (SELECT 
        key, 
        value
      FROM tbl 
      WHERE id = 1) AS s1
JOIN (SELECT 
        key, 
        value
      FROM tbl 
      WHERE id = 2) AS s2
  ON s1.contract = s2.contract;

Answer 3

去掉最外面的括号。