如何在MySQL中计算NULL值? [英] How to count NULL values in MySQL?

问题描述

我想知道如何在MySQL数据库中找到所有为NULL的值，例如，我试图显示尚未获得平均值的所有用户.

I want to know how can i find all the values that are NULL in the MySQL database for example I'm trying to display all the users who don't have an average yet.

这是MySQL代码.

SELECT COUNT(average) as num
FROM users
WHERE user_id = '$user_id'
AND average IS_NULL

推荐答案

SELECT
    COUNT(*) as num
FROM
    users
WHERE
    user_id = '$user_id' AND
    average IS NULL

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