mysql 存储过程编写游标

存储过程

 drop procedure if exists pro_change_type ;
 
create procedure pro_change_type(table_name varchar(50))  
  begin
		 -- 修改实体表字段
     -- 游标所使用变量需要在定义游标之前申明
     declare column_name varchar(50);
     -- 遍历数据结束标志 注意位置顺序
     DECLARE done INT DEFAULT FALSE;
     -- 注意用别名 因为id在上面已经有定义所以需要使用表的别名区别
     declare cur_test CURSOR for select name from BusinessObjectColumns where BusinessObjectId=(select ID from BusinessObjects where `Name`=table_name) and Type='decimal';
     -- 将结束标志绑定到游标 
     DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
     open cur_test;
          repeat
             fetch cur_test into column_name;
						 
						 -- mysql动态执行sql
						 SET @alter_table_query = CONCAT('ALTER TABLE ',table_name,' MODIFY COLUMN `',column_name,'` VARCHAR(50)'); 
						 PREPARE alter_table_stmt FROM @alter_table_query; 
						 EXECUTE alter_table_stmt;
						 DEALLOCATE PREPARE alter_table_stmt;  
          until done
	  end repeat;
		-- 注意关闭游标
    close cur_test;
		
		-- 修改配置表字段
		SET @update_query = CONCAT('update BusinessObjectColumns set Length=''50'',Type=''varchar'' where BusinessObjectId=(select ID from BusinessObjects where Name=?) and Type=''decimal''');  
		PREPARE update_stmt FROM @update_query; 
		set @table_name=table_name;
		EXECUTE update_stmt USING @table_name;  
		DEALLOCATE PREPARE update_stmt;  
		
 end;

调用

call pro_change_type('mdmemploymenttype');