更新时间:2020-03-24 10:05
存在条件(Exists Condition)用于测试子查询中是否存在指定的行。
EXISTS (subquery)
如果子查询至少返回一行,则说明存在您想要的数据。
SELECT department_id FROM departments d WHERE EXISTS (SELECT * FROM employees e WHERE d.department_id = e.department_id) ORDER BY department_id;
SELECT department_id FROM departments d WHERE EXISTS (SELECT * FROM employees e
WHERE d.department_id = e.department_id) ORDER BY department_id;
在文档使用中是否遇到以下问题
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在文档使用中是否遇到以下问题
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