MySQL遍历表

Question

我想从包含first_name列的每个表中输出数据。我编写了以下过程，但在我的循环中，mysql逐字解释表名，而不是计算变量table_name。修复方法是什么？

delimiter //

drop procedure if exists hunt //
create procedure hunt()
begin
    DECLARE done int default false;
    DECLARE table_name CHAR(255);

    DECLARE cur1 cursor for SELECT TABLE_NAME FROM INFORMATION_SCHEMA.COLUMNS 
        WHERE TABLE_SCHEMA = "wholesale_production" and COLUMN_NAME LIKE "%first%" ;
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
    open cur1;

    myloop: loop
        fetch cur1 into table_name;
        if done then
            leave myloop;
        end if;
        select * from `wholesale_production`.table_name where created_at >= '2012-10-01';
    end loop;

    close cur1;
end //

delimiter ;

call hunt();

Answer 1

试试这个：

delimiter //

drop procedure if exists hunt //
create procedure hunt()
begin
    DECLARE done BOOL default false;
    DECLARE tablename CHAR(255);

    DECLARE cur1 cursor for SELECT TABLE_NAME FROM INFORMATION_SCHEMA.COLUMNS 
        WHERE TABLE_SCHEMA = "wholesale_production" and COLUMN_NAME LIKE "%first%" ;
    DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
    open cur1;

    myloop: loop
        fetch cur1 into tablename;
        if done then
            leave myloop;
        end if;
        set @sql = CONCAT('select * from `wholesale_production`.', tablename, ' where created_at >= ''2012-10-01''');
        prepare stmt from @sql;
        execute stmt;
        drop prepare stmt;
    end loop;

    close cur1;
end //

delimiter ;

call hunt();

Answer 2

对上面的代码进行一点编辑，以迭代ahtoug所有的表并选择它们。

delimiter //
drop procedure if exists hunt //
create procedure hunt()
begin
    DECLARE done int default false;
    DECLARE table_name CHAR(255);

    DECLARE cur1 cursor for SELECT TABLE_NAME FROM INFORMATION_SCHEMA.TABLES
                  WHERE table_schema ='mbu4u';
   DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
    open cur1;
       myloop: loop
        fetch cur1 into table_name;
        if done then
            leave myloop;
        end if;
        set @sql = CONCAT('select * from `mbu4u`.',table_name);
        prepare stmt from @sql;
        execute stmt;
        drop prepare stmt;
    end loop;

    close cur1;
end //

delimiter //

Answer 3

table_name是使用"DECLARE table_name CHAR(255);“中另一个变量名的保留令牌