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.

原文链接:https://blog.csdn.net/wll_1017/article/details/55105180