select distinct CONCAT( 'ALTER TABLE ', table_name, ' CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;' ) from information_schema.`COLUMNS` where TABLE_SCHEMA='数据库名';
select distinct CONCAT( 'ALTER TABLE ', table_name, ' CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;' ) from information_schema.`COLUMNS` where TABLE_SCHEMA='数据库名';