小编典典

如何在整个数据库中更改 CHARACTER SET(和 COLLATION)?

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我们以前的程序员在表(Mysql)中设置了错误的排序规则。他用拉丁排序规则设置它,它应该是 UTF8,现在我遇到了问题。每条带有中日字符的记录都变成了???
特点。

是否可以更改排序规则并取回字符的详细信息?


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2022-07-04

共1个答案

小编典典

更改数据库排序规则:

ALTER DATABASE <database_name> CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci;

更改表排序规则:

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

更改列排序规则:

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

各部分是什么utf8mb4_0900_ai_ci意思?

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=谩)
_ai_ci    -- explicitly case insensitive and accent insensitive
_as (etc) -- accent-sensitive (etc)



_bin         -- simple, fast
_general_ci  -- fails to compare multiletters; eg ss=脽, somewhat fast
...          -- slower
_0900_       -- (8.0) much faster because of a rewrite
2022-07-04