Mysql 排序null值 排序問題分析

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mysql中null值的排序問題分析 如下表t_user： name agezhangsan 1lisi NULLwangwu 2  www.2cto.com  執行一下sql： Sql代碼  select * from t_user order by age;   name agelisi NULLzhangsan 1wangwu 2 實際上我們是想將沒有填寫age的記錄放在最後，我們可以 Sql代碼  select * from t_user order by age is null, age;   name agezhangsan 1wangwu 2lisi NULL 為什麼會這樣？可以這樣來理解： Sql代碼  select * from t_user order by age is null, age;   等價於: Sql代碼  select * from (select name, age, (age is null) as isnull from t_user) as foo order by isnull, age;

Mysql 排序null值 排序問題分析