不使用=运算符，您可能希望使用LIKE或LIKE二进制

// this returns 1 (true)
select 'A' like 'a'

// this returns 0 (false)
select 'A' like binary 'a'


select * from user where username like binary 'a'

在它的条件下，它会取a和不取a

好消息是，如果你需要进行区分大小写的查询，这很容易做到:

SELECT *  FROM `table` WHERE BINARY `column` = 'value'

http://dev.mysql.com/doc/refman/5.0/en/case-sensitivity.html

The default character set and collation are latin1 and latin1_swedish_ci, so nonbinary string comparisons are case insensitive by default. This means that if you search with col_name LIKE 'a%', you get all column values that start with A or a. To make this search case sensitive, make sure that one of the operands has a case sensitive or binary collation. For example, if you are comparing a column and a string that both have the latin1 character set, you can use the COLLATE operator to cause either operand to have the latin1_general_cs or latin1_bin collation:

col_name COLLATE latin1_general_cs LIKE 'a%'
col_name LIKE 'a%' COLLATE latin1_general_cs
col_name COLLATE latin1_bin LIKE 'a%'
col_name LIKE 'a%' COLLATE latin1_bin

如果希望始终以区分大小写的方式对待列，请使用区分大小写或二进制排序规则来声明它。

不需要改变任何DB级别，只是你必须改变SQL查询它将工作。

的例子,

“SELECT * FROM <TABLE> where userId = ' ' ' + iv_userId + ' ' AND password = ' ' ' ' ' + iv_password + ' '";

二进制关键字将区分大小写。

对于那些希望使用RLIKE或REGEXP与正则表达式进行区分大小写的比较的人来说，你可以使用REGEXP_LIKE()来匹配匹配类型c，如下所示:

SELECT * FROM `table` WHERE REGEXP_LIKE(`column`, 'value', 'c');

Mysql默认情况下不区分大小写，请尝试将语言排序规则更改为latin1_general_cs