CASE WHEN 在语句中不同位置的用法
1、SELECT CASE WHEN 用法
SELECT grade, COUNT (CASE WHEN sex = 1 THEN 1 /*sex 1为男生，2位女生*/ ELSE NULL END) 男生数, COUNT (CASE WHEN sex = 2 THEN 1 ELSE NULL END) 女生数 FROM students GROUP BY grade;
2、WHERE CASE WHEN 用法
SELECT T2.*, T1.* FROM T1, T2 WHERE (CASE WHEN T2.COMPARE_TYPE = 'A' AND T1.SOME_TYPE LIKE 'NOTHING%' THEN 1 WHEN T2.COMPARE_TYPE != 'A' AND T1.SOME_TYPE NOT LIKE 'NOTHING%' THEN 1 ELSE 0 END) = 1
3、group by case when 用法
SELECT CASE WHEN salary 500 AND salary 600 AND salary 800 AND salary 500 AND salary 600 AND salary 800 AND salary <p>推荐教程：<a href="https://www.php.cn/mysql-tutorials.html" target="_blank">mysql教程</a></p>
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