sql - 有人可以帮我指出这个简单的 WHERE 子句有什么问题吗？

Question

这很简单，但不知何故，我对我的数据库的这个查询做错了。

我在下面有这个查询:

SELECT login FROM accounts WHERE login = "loginname";

当我执行这个查询时，我得到的结果是这样的:

column "loginname" does not exist

这很简单，为什么这个查询不能正常工作？我有一个登录列，我知道这个用户存在，因为我已经通过 Rails 控制台找到了这个人。为什么登录条件将其自身称为列？

Answer 1

如果要匹配字符串，请尝试使用单引号 ''

SELECT login FROM accounts WHERE login = 'loginname';

检查 documentation

There is a second kind of identifier: the delimited identifier or quoted identifier. It is formed by enclosing an arbitrary sequence of characters in double-quotes ("). A delimited identifier is always an identifier, never a key word. So "select" could be used to refer to a column or table named "select", whereas an unquoted select would be taken as a key word and would therefore provoke a parse error when used where a table or column name is expected.