回答

1、写一个存储过程

-- ----------------------------
-- Procedure structure for batchAddField
-- ----------------------------
DROP PROCEDURE IF EXISTS `batchAddField`;
DELIMITER ;;
CREATE DEFINER=`root`@`%` PROCEDURE `batchAddField`(IN `tableName` varchar(100),IN `fieldName` varchar(100),IN `fieldType` varchar(100),IN `defaultValue` varchar(1000))
BEGIN

    #数据库名称
  DECLARE schemaName VARCHAR(100); 

  #声明结束标识
    DECLARE end_flag int DEFAULT 0;
    #声明游标 curosr ,查找所有“MyDB_”开头的数据库
    DECLARE curosr CURSOR FOR select  TABLE_SCHEMA   from information_schema.`TABLES`  WHERE TABLE_SCHEMA ='数据库名' and table_name = tableName;
  #设置终止标志
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET end_flag=1;

    #打开游标
    OPEN curosr;
    
    #遍历游标
    loop_label:  LOOP
        
        FETCH curosr INTO schemaName;#获取当前游标指针记录，取出值赋给自定义的变量
        
        IF end_flag > 0 THEN 
            LEAVE  loop_label;
        END IF;
    
        SET @sqlStr=CONCAT('alter table ',schemaName,'.',tableName,' add column `',fieldName,'`  ',fieldType,' DEFAULT ''',defaultValue,''' ');
    PREPARE stmt from @sqlStr;
    EXECUTE stmt;

    END LOOP;
    
  #关闭游标
    close curosr;
END
;;
DELIMITER ;

batchAddField('Users','score','int(8)','0') //添加int型字段score默认值：0
batchAddField('Users','memo','varchar(1000)','blank') //添加varchar型字段memo默认值：blank