MySQL不选择空值 [英] Mysql not selecting null values

问题描述

我有以下查询:

SELECT * FROM table 
WHERE orderdate >= "2015-12-01" 
    AND orderdate <= "2015-12-31" 
    AND values > 0 
    AND orders <> 'Returned'

问题在于查询不会返回订单列为NULL的行，我无法弄清原因.

The problem is that the query doesn't return the rows where the orders column is NULL and I can't figure out why.

推荐答案

这是sql语言. Mysql不会将NULL视为值.因此，如果要包含NULL，则必须指定它.

This is the sql language. Mysql doesn't consider NULL as value. So if you want to include NULL we must specify that.

SELECT * FROM table 
WHERE orderdate >= "2015-12-01" 
    AND orderdate <= "2015-12-31" 
    AND values > 0 
    AND (orders <> 'Returned' or orders is null)

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