1、参数含义：
lower_case_table_names： 此参数不可以动态修改，必须重启数据库
lower_case_table_names = 1 表名存储在磁盘是小写的，但是比较的时候是不区分大小写
lower_case_table_names=0 表名存储为给定的大小和比较是区分大小写的
lower_case_table_names=2, 表名存储为给定的大小写但是比较的时候是小写的
2、修改 参数lower_case_table_names 产生的问题
mysql> show variables like 'lower_case_table_names';
+------------------------+-------+
| Variable_name | Value |
+------------------------+-------+
| lower_case_table_names | 0 |
+------------------------+-------+
1 row in set (0.00 sec)
在mysql系统中原来的参数是lower_case_table_names=0 ，就是存储的时候区分大小写，创建了表Tt tT
mysql> create table Tt(id int);
Query OK, 0 rows affected (0.10 sec)
mysql> create table tT(id int);
Query OK, 0 rows affected (0.03 sec)
mysql> show tables;
+----------------+
| Tables_in_test |
+----------------+
| Tt |
| tT |
+----------------+
2 rows in set (0.00 sec)
修改参数 /etc/my.cnf 中设置 lower_case_table_names = 1
mysql> show variables like 'lower_case_table_names';
+------------------------+-------+
| Variable_name | Value |
+------------------------+-------+
| lower_case_table_names | 1 |
+------------------------+-------+
1 row in set (0.00 sec)
重启数据库
然后查看数据库
mysql> select * From tT;
ERROR 1146 (42S02): Table 'test.tt' doesn't exist
mysql> select * From tT;
ERROR 1146 (42S02): Table 'test.tt' doesn't exist
你可以发现当修改lower_case_table_names = 1后，之前创建的表名都不识别了
---创建表后，你可以发现表名不区分大小写
mysql> create table Tt(id int);
Query OK, 0 rows affected (0.23 sec)
mysql> show tables;
+-------------+
| Tables_in_t |
+-------------+
| tt |
+-------------+
1 row in set (0.00 sec)
从此可以看出lower_case_table_names = 1，创建表名，不区分大小写
结论：不能随意修改数据库的大小写，否则表名会认不出来
lower_case_table_names 参数的修改是非动态的，必须重启数据库
3、如何修改大小写格式
如果原来所建立库及表都是对大小写敏感的，想要转换为对大小写不敏感，主要需要进行如下3步：
1.将数据库数据通过mysqldump导出;
2.在my.cnf中更改lower_case_tables_name = 1，并重启mysql数据库。
3.将导出的数据导入mysql数据库中。
On Windows the default value is 1. On OS X, the default value is 2.
If you are using InnoDB tables, you should set this variable to 1 on all platforms to force names to be converted to lowercase.
In previous versions of MySQL, using different settings for lower_case_table_names on replication masters and slaves could cause replication to fail when the slave used a case-sensitive file system. This issue is resolved in MySQL 5.6.1.
You should not set lower_case_table_names to 0 if you are running MySQL on a system where the data directory resides on a case-insensitive file system (such as on Windows or OS X). It is an unsupported combination that could result in a hang condition when running an INSERT INTO ... SELECT ... FROM tbl_name operation with the wrong tbl_name letter case. WithMyISAM, accessing table names using different letter cases could cause index corruption.
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作者：wluckdog
来源：CSDN
原文：https://blog.csdn.net/wll_1017/article/details/55105180
版权声明：本文为博主原创文章，转载请附上博文链接！
