分表：批量为每张表添加字段

使用存储过程：

drop procedure if exists useCursor;

如果在mysql终端使用为命令终止符号，代替分号，因为分号在begin...end中会用到；

-> delimiter $$

CREATE PROCEDURE useCursor()

  BEGIN

    DECLARE oneAddr varchar(255) default '';

    DECLARE allAddr varchar(40) default '';

    DECLARE done INT DEFAULT 0;

    DECLARE curl CURSOR FOR select table_name from information_schema.tables where table_schema='shard1' and table_name like  'chat_%';

    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;

    OPEN curl;

    REPEAT

      FETCH curl INTO oneAddr;

      IF not done THEN

        set @sql=concat('alter table ',oneAddr,' add chat_id MEDIUMINT(8)  UNSIGNED NOT NULL DEFAULT 0');

        PREPARE stmt from @sql;

        execute stmt;

      END IF;

    UNTIL done END REPEAT;

    select allAddr;

    CLOSE curl; 

  END;

$$

call useCursor()$$

最后在还原最终符号delimiter ;