MySQL WHERE: how to write “!=” or “not equals”?

问题

I need to do this

DELETE FROM konta WHERE taken != ''

But != doesn't exist in mysql. Anyone know how to do this?

回答1:

DELETE FROM konta WHERE taken <> '';

回答2:

The != operator most certainly does exist! It is an alias for the standard <> operator.

Perhaps your fields are not actually empty strings, but instead NULL?

To compare to NULL you can use IS NULL or IS NOT NULL or the null safe equals operator <=>.

回答3:

You may be using old version of Mysql but surely you can use

 DELETE FROM konta WHERE taken <> ''

But there are many other options available. You can try the following ones

DELETE * from konta WHERE strcmp(taken, '') <> 0;

DELETE * from konta where NOT (taken = '');

来源：https://stackoverflow.com/questions/11421741/mysql-where-how-to-write-or-not-equals