mysql - SQL BUG doesn't accept null when write != -

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this question has answer here:

when write column!=something doesn't choose null value , something. why happened? can prevent writing , column null?

you need check null too.

select  * your_table column <> or column null

note: cannot compare null null.

let's @ following code snippets:

set @v := null; select @v = null; result: null; because null can compared using null  select @v null; result: 1 (i.e. true)

the null value can surprising until used it. conceptually, null means “a missing unknown value” , treated differently other values.

to test null, use null , not null

working null values in mysql


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