1.修改表字段字符集

语句：

ALTER TABLE {table_name} CHANGE {field} {field} {field_type} CHARACTER SET {character_name} [other_attribute];

导出 sql：

SELECT CONCAT('ALTER TABLE `',TABLE_SCHEMA,'`.`',TABLE_NAME,'` CHANGE `',column_name,'` `',
 column_name,'` ',
 COLUMN_TYPE,
 ' CHARSET utf8mb4 COLLATE utf8mb4_general_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 = '数据库'
AND (CHARACTER_SET_NAME = 'utf8'
OR COLLATION_NAME = 'utf8mb4_0900_ai_ci'
or COLLATION_NAME = 'utf8mb4_unicode_ci');

2.修改表字符集

语句：

ALTER TABLE {table_name} DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;

搜索数据库表 sql：

SELECT TABLE_NAME from information_schema.`TABLES` WHERE TABLE_SCHEMA = '数据库';

导出 sql:

SELECT CONCAT('ALTER TABLE ',TABLE_NAME,' DEFAULT CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;')
from information_schema.`TABLES` WHERE TABLE_SCHEMA = '数据库';

3.修改表引擎

语句：

ALTER TABLE {table_name} ENGINE=InnoDB;

搜索数据库表 sql：

SELECT TABLE_NAME,
 ENGINE
FROM information_schema.TABLES
WHERE TABLE_SCHEMA =  '数据库' AND ENGINE = 'myISAM';

导出 sql:

SELECT CONCAT('ALTER TABLE ',TABLE_NAME,' ENGINE=InnoDB;')
from information_schema.`TABLES` WHERE TABLE_SCHEMA = '数据库' AND ENGINE = 'myISAM';