如何在PL/SQL中连接子查询？

我需要在oracle中加入子查询。如果联接操作出现语法错误，则此操作无效

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);

---

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;

---

去掉最外面的圆括号。

您应该在内联视图中选择要加入合同的字段：

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;

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

---

明确提及连接的类型，即内部连接、左侧外部连接等。您能发布准确的错误消息吗？您正在连接不在内联视图中的列协定。去掉最外面的括号并指定内部联接的类型解决了问题。对于我来说，我必须删除表别名上的as：SELECT s1.key、s1.value、s2.value FROM SELECT CONTACT、key、，来自tbl的值，其中id=1 s1连接选择合同，键，来自tbl的值，其中id=2 s2在s1.contract=s2.contract上