Mysql
 sql >> Database >  >> RDS >> Mysql

Come modificare il CHARACTER SET (e COLLATION) in un database?

cambia le regole di confronto del database:

ALTER DATABASE <database_name> CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci;

cambia le regole di confronto delle tabelle:

ALTER TABLE <table_name> CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci;

cambia le regole di confronto delle colonne:

ALTER TABLE <table_name> MODIFY <column_name> VARCHAR(255) CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci;

Cosa fanno le parti di utf8mb4_0900_ai_ci intendi?

3 bytes -- utf8
4 bytes -- utf8mb4 (new)

v4.0 --   _unicode_
v5.20 --  _unicode_520_
v9.0 --   _0900_ (new)

_bin      -- just compare the bits; don't consider case folding, accents, etc
_ci       -- explicitly case insensitive (A=a) and implicitly accent insensitive (a=á)
_ai_ci    -- explicitly case insensitive and accent insensitive
_as (etc) -- accent-sensitive (etc)

_bin         -- simple, fast
_general_ci  -- fails to compare multiletters; eg ss=ß, somewhat fast
...          -- slower
_0900_       -- (8.0) much faster because of a rewrite

Maggiori informazioni: