MYSQL IN语句，其中值不区分大小写

Question

I am currently trying to whitelist/blacklist based on user input with the following SQL statements:

SELECT * FROM Customers WHERE City IN ('Paris','London');
SELECT * FROM Customers WHERE City NOT IN ('Paris','London');

What syntax is needed such that Paris and London are case insensitive and match paris and london?

Thanks.

Answer 1

Just define the proper collation on your db fields and index will work fine too.

http://dev.mysql.com/doc/refman/5.7/en/case-sensitivity.html

As you can see with latin1_bin 'MySQL' <> 'mysql'

mysql> SET @s1 = 'MySQL' COLLATE latin1_bin,
    ->     @s2 = 'mysql' COLLATE latin1_bin;
mysql> SELECT @s1 = @s2;
+-----------+
| @s1 = @s2 |
+-----------+
|         0 |
+-----------+

But with latin1_swedish_ci are equal

mysql> SELECT @s1 COLLATE latin1_swedish_ci = @s2;
+-------------------------------------+
| @s1 COLLATE latin1_swedish_ci = @s2 |
+-------------------------------------+
|                                   1 |
+-------------------------------------+

Answer 2

您可以执行此操作，但是如果您索引City希望优化查询，则添加LOWER函数将终止优化：

SELECT * FROM Customers WHERE LOWER(City) IN ('paris', 'london');