Fifteen. Actual combat - MySQL database building table character set and collation

1. Character set and collation

Character Set

When the database needs to adapt to different languages, it needs to have different character sets. If the character set is not specified, then the default character set of the database will be used. Each character set has its own default collation rules.The default character set of mysql is utf8, and the default collation is utf8_general_ci.Generally, we will also choose the character set as utf-8

Collation

Each character set will have its own collation, and the collation suffix is ​​generally divided into cs, ci

• cs: case sensitive is translated as case sensitive
• ci: case insensitive is translated as case insensitive

Example:

select * from test where column1 like "A%"

If we choose cs, then we will choose the beginning of A
If we choose ci, then we will choose the beginning of a or A

In the case of uncertain case, we usually choose ci, which is not sensitive and can choose a little more range
Original: https://blog.csdn.net/aduoge/article/details/116501560

2. The difference between utf8 and utf8mb4:

MySQL added this utf8mb4 encoding after 5.5.3. utf8mb4 is completely backward compatible with utf8. In order to save space, it is usually enough to use utf8.
Original: https://www.fujieace.com/mysql/utf8-utf8mb4.html