mysql 修改数据库表的默认字符集及排序方式

mysql 修改数据库表的默认字符集及排序方式

以将原来的UTF8修改为 utf8mb4  ，utf8_general_ci 修改为 utf8mb4_unicode_ci 为例

其他字符集变更，需要注意编码是否兼容

将 databasename 换成你的数据库名称，注意帐号权限

-- 修改数据库
ALTER DATABASE `databasename` CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

-- 修改表
SELECT DISTINCT CONCAT('ALTER TABLE `',TABLE_SCHEMA,'`.`',TABLE_NAME,'` CHARSET=utf8mb4, COLLATE=utf8mb4_unicode_ci;') AS sqltext
FROM `information_schema`.`COLUMNS` WHERE table_schema = 'databasename' AND (CHARACTER_SET_NAME = 'utf8' OR COLLATION_NAME = 'utf8mb4_general_ci')
将结果集复制出来，执行

-- 修改字段
SELECT CONCAT('ALTER TABLE `',TABLE_SCHEMA,'`.`',TABLE_NAME,'` CHANGE `',column_name,'` `',
column_name,'` ',
COLUMN_TYPE,
' CHARSET utf8mb4 COLLATE utf8mb4_unicode_ci ',IF(IS_NULLABLE = 'NO', 'NOT NULL', 'NULL'),
' ',
IF(ISNULL(COLUMN_DEFAULT), '', CONCAT('default \'', COLUMN_DEFAULT, "'")),
';') AS sqltext
FROM `information_schema`.`COLUMNS` WHERE table_schema = 'databasename' AND (CHARACTER_SET_NAME = 'utf8' OR COLLATION_NAME = 'utf8mb4_general_ci')
将结果集复制出来，执行

-- 修改字段更新了一下，将一个表的修改合并

注意 group_concat 的长度，如果不够，修改一下，需要 root 权限
-- SET GLOBAL group_concat_max_len=102400;
-- SET SESSION group_concat_max_len=102400;

SELECT alterstr, GROUP_CONCAT(columntext), ';' FROM (
SELECT CONCAT('ALTER TABLE `',TABLE_SCHEMA,'`.`',TABLE_NAME, '` ') AS alterstr,
CONCAT('CHANGE `', column_name,'` `', column_name,'` ', COLUMN_TYPE,
' CHARSET utf8mb4 COLLATE utf8mb4_unicode_ci ',IF(IS_NULLABLE = 'NO', 'NOT NULL', 'NULL'),
' ',
IF(ISNULL(COLUMN_DEFAULT), '', CONCAT('default \'', COLUMN_DEFAULT, "'")) ) AS columntext
FROM `information_schema`.`COLUMNS`
WHERE table_schema = 'guangying_shop'
AND (CHARACTER_SET_NAME = 'utf8' OR COLLATION_NAME = 'utf8mb4_general_ci')
) a
GROUP BY alterstr