MySQL WHERE：如何写“！=”或“不等于”？
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MySQL WHERE: how to write "!=" or "not equals"?
提问by Posttwo
I need to do this
我需要这样做
DELETE FROM konta WHERE taken != ''
But != doesn't exist in mysql. Anyone know how to do this?
但是 != 在 mysql 中不存在。有人知道怎么做吗？
回答by RolandoMySQLDBA
DELETE FROM konta WHERE taken <> '';
回答by Mark Byers
The != operatormost certainly does exist! It is an alias for the standard <>operator.
该！=操作肯定是存在的！它是标准<>运算符的别名。
Perhaps your fields are not actually empty strings, but instead NULL?
也许您的字段实际上不是空字符串，而是NULL?
To compare to NULLyou can use IS NULLor IS NOT NULLor the null safe equals operator <=>.
为了与NULL您进行比较，您可以使用IS NULL或IS NOT NULL或空安全等于运算符<=>。
回答by minhas23
You may be using old version of Mysql but surely you can use
您可能使用的是旧版本的 Mysql，但您肯定可以使用
DELETE FROM konta WHERE taken <> ''
But there are many other options available. You can try the following ones
但是还有许多其他选项可用。你可以试试下面的
DELETE * from konta WHERE strcmp(taken, '') <> 0;
DELETE * from konta where NOT (taken = '');
