mySQL将多个查询变成单个查询

Question

我有两个 mySQL 表:

tblcoach:包含字段(coachid、coachschoolid、其他)

tblschool:包含字段(schoolid、schooldivision)

我正在尝试获取一份学校列表，该列表仅限于与教练位于同一学区的学校。

我的这段代码可以工作，但是有没有办法生成单个 mySQL 查询来实现相同的结果？

SELECT @cs := coachschoolid FROM tblcoach c;
SELECT @sd := s.schooldivision FROM tblschool s WHERE s.schoolid = @cs;
SELECT s2.schoolid, s2.schoolname FROM tblschool s2 WHERE schooldivision = @sd

Answer 1

嵌套查询:

select schoolId, schoolname
from tblschool
where 
    schooldivision = (
        select schooldivision from tblschool where schoolid = (
            select coachschoolid from tblcoach
        )
    )