After the mysql link is established, the encoding is set as follows:

mysql_query("SET character_set_connection=" . $GLOBALS['charset'] . ",character_set_results=" . $GLOBALS['charset'] . ",character_set_client=binary", $this->link);

However, the resulting table structure description turned out to be garbled:

mysql> show create table nw_admin_config\G
*************************** 1. row ***************************
Table: nw_admin_config
Create Table: CREATE TABLE `nw_admin_config` (
`name` varchar(30) NOT NULL DEFAULT '' COMMENT '��������',
`namespace` varchar(15) NOT NULL DEFAULT 'global' COMMENT '���������ռ�',
`value` text COMMENT '����ֵ',
`vtype` enum('string','array','object') NOT NULL DEFAULT 'string' COMMENT '����ֵ����',
`description` text COMMENT '���ý���',
PRIMARY KEY (`namespace`,`name`)
) ENGINE=MyISAM DEFAULT CHARSET=gbk COMMENT='��վ���ñ�'

After investigation, it turned out that character_set_client=binary was to blame:

$targetDb->query("SET NAMES '{$charset}'");

mysql> show create table nw_admin_config\G
*************************** 1. row ***************************
Table: nw_admin_config
Create Table: CREATE TABLE `nw_admin_config` (
`name` varchar(30) NOT NULL DEFAULT '' COMMENT ' The name of the configuration ',
`namespace` varchar(15) NOT NULL DEFAULT 'global' COMMENT ' Configure the namespace ',
`value` text COMMENT ' The cache value ',
`vtype` enum('string','array','object') NOT NULL DEFAULT 'string' COMMENT ' Configuration value type ',
`description` text COMMENT ' Configuration is introduced ',
PRIMARY KEY (`namespace`,`name`)
) ENGINE=MyISAM DEFAULT CHARSET=gbk COMMENT=' Site profile '

However, if the character set I set is UTF8 and the table structure is utf8, then even if the character_set_client=binary above is used, the table structure description is normal:

mysql> show create table nw_admin_config\G
*************************** 1. row ***************************
Table: nw_admin_config
Create Table: CREATE TABLE `nw_admin_config` (
`name` varchar(30) NOT NULL DEFAULT '' COMMENT ' The name of the configuration ',
`namespace` varchar(15) NOT NULL DEFAULT 'global' COMMENT ' Configure the namespace ',
`value` text COMMENT ' The cache value ',
`vtype` enum('string','array','object') NOT NULL DEFAULT 'string' COMMENT ' Configuration value type ',
`description` text COMMENT ' Configuration is introduced ',
PRIMARY KEY (`namespace`,`name`)
) ENGINE=MyISAM DEFAULT CHARSET=utf8 COMMENT=' Site profile '

And strange thing, garbled code only exists in the description of the table structure, for the inserted data Chinese is still normal ~

I checked character_set_client=binary on the Internet and said that “most of them are set to solve the problem of scrambled codes”, but I do not know that this description of the table structure turned out to be scrambled codes. What exactly does this do? Why don’t you do the same with the table structure?