0字符串搜索返回的行数

Question

查询=

SELECT * FROM options WHERE 'key' = 'exchange_rate'

表结构=

key varchar(500)    latin1_swedish_ci   
value   text    latin1_swedish_ci

表格内容

Key           | Value
exchange_rate | 25

程序

phpMyAdmin 4.0.4 Mysql

结果

0 Rows returned

你知道这里的问题是什么吗？

Answer 1

尝试此查询：

SELECT * FROM options WHERE `key` = 'exchange_rate'

而不是：

SELECT * FROM options WHERE 'key' = 'exchange_rate'

Answer 2

Qoutes用于显示varchar值而非列名

SELECT * FROM options WHERE `key` = 'exchange_rate'