MySQL 避免 WHERE/AND 中的子查询重复

Question

我有一个 SQL 查询，我在 WHERE 子句中使用子查询。然后我需要再次使用相同的子查询将其与不同的列进行比较。

我假设没有办法在子查询之外访问“emp_education_list li”？

我猜子查询重复是多余的。坦率地说，我对 SQL 有点生疏。

SELECT e.fname, e.lname
    FROM employee e, emp_education_list l
    WHERE
        e.skillsID = l.skillsID
    AND
    (
        SELECT li.educationID
            FROM emp_education_list li, job j
            WHERE j.skillsID = li.skillsID
            AND j.jobID = 1001
    ) = l.educationID
    AND
    (
        SELECT li.edu_level
            FROM emp_education_list li, job j
            WHERE j.skillsID = li.skillsID
            AND j.jobID = 1001
    ) < l.edu_level
;

Answer 1

尝试一下，

SELECT  e.fname, e.lname
FROM    employee e 
        INNER JOIN emp_education_list l
            ON e.skillsID = l.skillsID
        INNER JOIN
        (
            SELECT  li.educationID, li.edu_level
            FROM    emp_education_list li
                    INNER JOIN job j 
                        ON j.skillsID = li.skillsID
            WHERE   j.jobID = 1001
        ) x ON  l.educationID = x.educationID
WHERE   x.edu_level < l.edu_level