如何理解MySQL關(guān)于表名大小寫的參數(shù)

今天就跟大家聊聊有關(guān)如何理解MySQL關(guān)于表名大小寫的參數(shù)，可能很多人都不太了解，為了讓大家更加了解，小編給大家總結(jié)了以下內(nèi)容，希望大家根據(jù)這篇文章可以有所收獲。

查看現(xiàn)有的大小寫參數(shù)
[mysql@localhost percona]$ bin/mysql --defaults-file=/u01/mysql_data/my.cnf -uroot -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 6
Server version: 5.7.17-11-log Percona Server (GPL), Release 11, Revision f60191c

mysql> show variables like '%lower%';
+------------------------+-------+
| Variable_name          | Value |
+------------------------+-------+
| lower_case_file_system | OFF   |
| lower_case_table_names | 1     |
+------------------------+-------+
2 rows in set (0.00 sec)

lower_case_table_names的值為1，代表數(shù)據(jù)庫的表名不區(qū)分大小寫

mysql> use test
Database changed

mysql> show tables;
+----------------+
| Tables_in_test |
+----------------+
| b              |
| c              |
| cpu_stat       |
| p              |
| support_his    |
| t              |
| v_t            |
| z              |
+----------------+
8 rows in set (0.00 sec)

mysql> select * from t;
+---+
| a |
+---+
| 1 |
| 2 |
| 3 |
+---+
3 rows in set (0.04 sec)

mysql> select * from T;
+---+
| a |
+---+
| 1 |
| 2 |
| 3 |
+---+
3 rows in set (0.00 sec)

這個參數(shù)是靜態(tài)參數(shù)，不能在線修改，需要修改配置文件
mysql> set global lower_case_table_names=0;
ERROR 1238 (HY000): Variable 'lower_case_table_names' is a read only variable

關(guān)閉數(shù)據(jù)庫
[mysql@localhost percona]$ bin/mysqladmin -uroot -S /u01/mysql_data/mysql.sock shutdown -p

修改參數(shù)
[mysql@localhost percona]$ vim /u01/mysql_data/my.cnf
[mysqld]
lower_case_table_names                          = 0

重啟數(shù)據(jù)庫
[mysql@localhost percona]$ bin/mysqld_safe --defaults-file=/u01/mysql_data/my.cnf &

[mysql@localhost percona]$ bin/mysql --defaults-file=/u01/mysql_data/my.cnf -uroot -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.7.17-11-log Percona Server (GPL), Release 11, Revision f60191c

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> use test
Database changed
mysql> show variables like '%lower%';
+------------------------+-------+
| Variable_name          | Value |
+------------------------+-------+
| lower_case_file_system | OFF   |
| lower_case_table_names | 0     |
+------------------------+-------+
2 rows in set (0.01 sec)

mysql> select * from T;
ERROR 1146 (42S02): Table 'test.T' doesn't exist
mysql> select * from t;
+---+
| a |
+---+
| 1 |
| 2 |
| 3 |
+---+
3 rows in set (0.02 sec)

注意：不建議在生產(chǎn)庫上面修改這個參數(shù)，可能導(dǎo)致現(xiàn)有的庫不能使用

參數(shù)lower_case_file_system決定操作系統(tǒng)中文件名的大小寫，是只讀的，不能修改


[mysql@localhost percona]$ cd /u01/mysql_data/test/
[mysql@localhost test]$ ls
b.frm  b.ibd  c.frm  c.ibd  cpu_stat.frm  cpu_stat.ibd  db.opt  p.frm  p.ibd  support_his.frm  support_his.ibd  t.frm  t.ibd  v_t.frm  z.frm  z.ibd

看完上述內(nèi)容，你們對如何理解MySQL關(guān)于表名大小寫的參數(shù)有進(jìn)一步的了解嗎？如果還想了解更多知識或者相關(guān)內(nèi)容，請關(guān)注億速云行業(yè)資訊頻道，感謝大家的支持。