mysql-5.7.26 版本，表不区分区分大小写问题

一、问题描述: 查询某张表没有记录，或者不存在，明明是有这个表的。

mysql> select * from cm_version;
+---------+--------------------------------------+---------------------+------+-----------------------------------+-----------------------+
| VERSION | GUID | LAST_UPDATE_INSTANT | TS | HOSTNAME | LAST_ACTIVE_TIMESTAMP |
+---------+--------------------------------------+---------------------+------+-----------------------------------+-----------------------+
| 5.13.3 | 1e440f97-6cea-403c-b712-f853b2a74752 | 1576748189778 | NULL | dataexa-cdh-test-01/192.168.1.228 | 1576830025460 |
+---------+--------------------------------------+---------------------+------+-----------------------------------+-----------------------+

mysql> select * from CM_VERSION;
ERROR 1146 (42S02): Table ‘cm.cm_vsersion‘ doesn‘t exist

二、原因是：5.6.+ 数据库里面的表默认区分大小写

lower_case_table_names参数详解：

lower_case_table_names=1

其中0：区分大小写，1：不区分大小写

mysql> show variables like ‘%lower%‘;
+------------------------+-------+
| Variable_name | Value |
+------------------------+-------+
| lower_case_file_system | OFF |
| lower_case_table_names | 0 |
+------------------------+-------+
2 rows in set (0.00 sec)

三、解决：

在/etc/my.cnf

[mysqld] 插入

lower_case_table_names=1

重启mysql，在检查

[client]
port = 31061
socket = /home/ap/mysql/mysql.sock
[mysqld]
server_id=10
port = 31061
user = mysql
character-set-server = utf8mb4
default_storage_engine = innodb
lower_case_table_names=1
log_timestamps = SYSTEM
socket = /home/ap/mysql/mysql.sock
basedir =/home/ap/mysql
datadir = /home/ap/mysql/data
pid-file = /home/ap/mysql/mysql.pid
max_connections = 1000
max_connect_errors = 1000
table_open_cache = 1024
max_allowed_packet = 128M
open_files_limit = 65535
server-id=1
gtid_mode=on
enforce_gtid_consistency=on
log-slave-updates=1
log-bin=master-bin
log-bin-index = master-bin.index
relay-log = relay-log
relay-log-index = relay-log.index
binlog_format=row
log_error = /home/ap/mysql/log/mysql-error.log 
skip-name-resolve
log-slave-updates=1
relay_log_purge = 0 
slow_query_log = 1
long_query_time = 1 
slow_query_log_file = /home/ap/mysql/log/mysql-slow.log

3.1重启mysql命令

/etc/init.d/mysql restart

3.2再次验证

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)

mysql> select * from CM_VERSION;
+---------+--------------------------------------+---------------------+------+-----------------------------------+-----------------------+
| VERSION | GUID | LAST_UPDATE_INSTANT | TS | HOSTNAME | LAST_ACTIVE_TIMESTAMP |
+---------+--------------------------------------+---------------------+------+-----------------------------------+-----------------------+
| 5.13.3 | 1e440f97-6cea-403c-b712-f853b2a74752 | 1576748189778 | NULL | dataexa-cdh-test-01/192.168.1.228 | 1576830522188 |
+---------+--------------------------------------+---------------------+------+-----------------------------------+-----------------------+
1 row in set (0.00 sec)