MySQL character set

The following is an introduction mysql Four levels of character sets and comparison rules

1. Server level

mysql> show variables like '%server';
+----------------------+-------------+
| Variable_name        | Value       |
+----------------------+-------------+
| character_set_server | utf8mb4     |  Server character set 
| collation_server     | utf8mb4_bin |  Server comparison rule 
+----------------------+-------------+
2 rows in set (0.00 sec)

The above parameters can be used at runtime set Statement to modify , It can also be configured in the configuration file

[server]
character_set_server=utf8mb4 
collation_server=utf8mb4_bin

2. Database level

mysql> show variables like '%database';
+------------------------+-------------+
| Variable_name          | Value       |
+------------------------+-------------+
| character_set_database | utf8mb4     |
| collation_database     | utf8mb4_bin |
| skip_show_database     | OFF         |
+------------------------+-------------+
3 rows in set (0.00 sec)

The above parameters can only be specified when creating the database , It can't be modified

3. Table level

The character set at the table level is used when the table is created without specifying the character set at the library level , If specified, use the character set at the time of creation , You can also modify the character set of the table later

alter table character set  Character set name  collation  Compare the rules 

4. Column level

Similarly, you can specify the character set of the column when creating the table , Use tables without making them , It can also be modified later