Mysql5 writing and reading garbled code solution_PHP tutorial

The example I wrote

Of course we do too You can modify the character set of the database through the following command
alter database da_name default character set 'charset'.
The client sends it in gbk format, and you can use the following configuration:
SET character_set_client='gbk'
SET character_set_connection='gbk'
SET character_set_results='gbk'
This configuration is equivalent to SET NAMES 'gbk'.
Now operate the database just created
mysql> use test;
Database changed
mysql> insert into mysqlcode values(null,'php enthusiast');
ERROR 1406 (22001) : Data too long for column 'content' at row 1
The character set is not specified as gbk, an error occurred during insertion
mysql> set names 'gbk';
Query OK, 0 rows affected (0.02 sec)
The specified character set is gbk
mysql> insert into mysqlcode values(null,'php lovers');
Query OK, 1 row affected (0.00 sec)
Insertion successful
mysql> select * from mysqlcode;
+----+-----------+
| id | content |
+----+-------- ---+
| 1 | php hobby |
+----+-----------+
1 row in set (0.00 sec)
In When the character set gbk is not specified, garbled characters will appear when reading, as follows
mysql> select * from mysqlcode;
+----+---------+
| id | content |
+----+---------+
| 1 | php??? |
+----+---------+
1 row in set (0.00 sec)