-- 修改数据库。 ly-plat 为你的表名
ALTER DATABASE ly-plat
CHARACTER SET utf8mb4
COLLATE utf8mb4_0900_ai_ci;

-- 生成修改字段的SQL
SELECT CONCAT(
'ALTER TABLE ', TABLE_NAME, ' MODIFY ', COLUMN_NAME, ' ',
COLUMN_TYPE, ' CHARACTER SET utf8mb4 COLLATE utf8mb4_0900_ai_ci ',
IF(IS_NULLABLE = 'NO', 'NOT NULL', 'NULL'),
IF(COLUMN_DEFAULT IS NOT NULL AND COLUMN_DEFAULT != 'NULL',

 CONCAT(' DEFAULT ', QUOTE(COLUMN_DEFAULT)), 
 ''),

' COMMENT ', QUOTE(COLUMN_COMMENT), ';'
) AS sql_statement
FROM information_schema.COLUMNS
WHERE TABLE_SCHEMA = 'ly-plat'
AND CHARACTER_SET_NAME = 'utf8mb4'
AND COLLATION_NAME != 'utf8mb4_0900_ai_ci';