sql - 列“玛丽”不存在

Question

我在这里做一个简单的查询，它返回“玛丽”列不存在：

SELECT  telephone.telephonenumber as tel
FROM    person, telephone
WHERE   person.idperson = telephone.idperson
AND person.personname = ‘Mary’;

有人可以解释会发生什么吗？我不希望 Mary 作为一列，而是作为一个值。

在此先感谢，加布里埃尔

Answer 1

Answer 2

Make sure that you are quoting your string correctly.

From your snippet, I'd say that's the problem here since you're using something else than simple single quotes.