从子句而不是子句中的临时表中

Question

我有此查询（完美运行）：

WITH TEMPTABLE AS(
            SELECT count(CONTRACT_ID) AS no_contract, T.BRANCH_ID as branch
            FROM CONTRACT, "EMPLOYMENT" T, TABLE(T."EMPLOYEE") TT
            WHERE CONTRACT.EMPLOYEE_ID = TT.EMPLOYEE_ID
                  AND CONTRACT.CONTRACT_VT_START BETWEEN '01/01/2018' AND '30/06/2018'
            GROUP BY T.BRANCH_ID
        )
        SELECT branch
        FROM TEMPTABLE
        WHERE no_contract IN (SELECT MAX(no_contract)
                             FROM TEMPTABLE);

我想知道它是否可以通过另一种方式而不是子句来完成。这样的东西：

SELECT count_per_branch.BRANCH
FROM (SELECT count(CONTRACT_ID) AS no_contract, BRANCH_ID AS BRANCH
      FROM CONTRACT, "EMPLOYMENT" T, TABLE(T."EMPLOYEE") TT
      WHERE CONTRACT.EMPLOYEE_ID = TT.EMPLOYEE_ID
            AND CONTRACT.CONTRACT_VT_START BETWEEN '01/01/2018' AND '30/06/2018'
      GROUP BY T.BRANCH_ID) count_per_branch
WHERE count_per_branch.no_contract =
            (SELECT max(count_per_branch.no_contract)
             FROM count_per_branch);

给出一个ORA-00942："不存在表或视图"线路错误：9

Answer 1

您可以在从子句中使用子查询：

FROM (SELECT count(CONTRACT_ID) ... )

您可以给它一个别名：

FROM (SELECT count(CONTRACT_ID) ... ) count_per_branch

您可以使用该别名来限定列参考：

WHERE count_per_branch.no_contract =

但是您不能使用该别名作为另一个子查询中的行源，这是您在这里尝试做的：

(SELECT max(count_per_branch.no_contract)
 FROM count_per_branch)

要以这种方式"重用"子查询，您必须使用常见的表表达语法 - 即，with with with strause。