我有一个函数,返回5个混合大小写字符。如果我对这个字符串进行查询,不管大小写,它都会返回值。
如何使MySQL字符串查询区分大小写?
我有一个函数,返回5个混合大小写字符。如果我对这个字符串进行查询,不管大小写,它都会返回值。
如何使MySQL字符串查询区分大小写?
当前回答
要在使用BINARY之前使用索引,如果有大型表,可以这样做。
SELECT
*
FROM
(SELECT * FROM `table` WHERE `column` = 'value') as firstresult
WHERE
BINARY `column` = 'value'
子查询将生成一个非常小的不区分大小写的子集,然后选择其中唯一区分大小写的匹配项。
其他回答
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');
您可以像这样使用二进制区分大小写
select * from tb_app where BINARY android_package='com.Mtime';
不幸的是,此SQL不能使用索引,依赖于该索引的查询将遭受性能损失
mysql> explain select * from tb_app where BINARY android_package='com.Mtime';
+----+-------------+--------+------------+------+---------------+------+---------+------+---------+----------+-------------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+-------------+--------+------------+------+---------------+------+---------+------+---------+----------+-------------+
| 1 | SIMPLE | tb_app | NULL | ALL | NULL | NULL | NULL | NULL | 1590351 | 100.00 | Using where |
+----+-------------+--------+------------+------+---------------+------+---------+------+---------+----------+-------------+
幸运的是,我有一些技巧来解决这个问题
mysql> explain select * from tb_app where android_package='com.Mtime' and BINARY android_package='com.Mtime';
+----+-------------+--------+------------+------+---------------------------+---------------------------+---------+-------+------+----------+-----------------------+
| id | select_type | table | partitions | type | possible_keys | key | key_len | ref | rows | filtered | Extra |
+----+-------------+--------+------------+------+---------------------------+---------------------------+---------+-------+------+----------+-----------------------+
| 1 | SIMPLE | tb_app | NULL | ref | idx_android_pkg | idx_android_pkg | 771 | const | 1 | 100.00 | Using index condition |
+----+-------------+--------+------------+------+---------------------------+---------------------------+---------+-------+------+----------+-----------------------+
要在使用BINARY之前使用索引,如果有大型表,可以这样做。
SELECT
*
FROM
(SELECT * FROM `table` WHERE `column` = 'value') as firstresult
WHERE
BINARY `column` = 'value'
子查询将生成一个非常小的不区分大小写的子集,然后选择其中唯一区分大小写的匹配项。
克雷格·怀特(Craig White)发布的答案有很大的性能损失
SELECT * FROM `table` WHERE BINARY `column` = 'value'
因为它不使用索引。所以,要么你需要像这里提到的那样改变表的排序规则https://dev.mysql.com/doc/refman/5.7/en/case-sensitivity.html。
OR
最简单的解决方法,你应该使用二进制值。
SELECT * FROM `table` WHERE `column` = BINARY 'value'
E.g.
mysql> EXPLAIN SELECT * FROM temp1 WHERE BINARY col1 = "ABC" AND col2 = "DEF" ;
+----+-------------+--------+------+---------------+------+---------+------+--------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+--------+------+---------------+------+---------+------+--------+-------------+
| 1 | SIMPLE | temp1 | ALL | NULL | NULL | NULL | NULL | 190543 | Using where |
+----+-------------+--------+------+---------------+------+---------+------+--------+-------------+
VS
mysql> EXPLAIN SELECT * FROM temp1 WHERE col1 = BINARY "ABC" AND col2 = "DEF" ;
+----+-------------+-------+-------+---------------+---------------+---------+------+------+------------------------------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+-------+---------------+---------------+---------+------+------+------------------------------------+
| 1 | SIMPLE | temp1 | range | col1_2e9e898e | col1_2e9e898e | 93 | NULL | 2 | Using index condition; Using where |
+----+-------------+-------+-------+---------------+---------------+---------+------+------+------------------------------------+
enter code here
set中的1行(0.00秒)
太好了!
我和你们分享一个比较密码的函数的代码:
SET pSignal =
(SELECT DECODE(r.usignal,'YOURSTRINGKEY') FROM rsw_uds r WHERE r.uname =
in_usdname AND r.uvige = 1);
SET pSuccess =(SELECT in_usdsignal LIKE BINARY pSignal);
IF pSuccess = 1 THEN
/*Your code if match*/
ELSE
/*Your code if don't match*/
END IF;