流程，先打印出 SQL 语句，然后再 MySQL 中执行！
1，批量修改表前缀
SELECT CONCAT( 'ALTER TABLE ', table_name, ' RENAME TO db_', substring(table_name, 4), ';' ) FROM information_schema. TABLES WHERE table_name LIKE 'ct%';
2，批量删除表！
SELECT CONCAT( 'drop table ', table_name, ';' ) FROM information_schema. TABLES WHERE table_name LIKE 'uc_%';
