MySQL存储过程获取记录排名(一般用于投票系统)
MySQL存储过程获取记录排名(一般用于投票系统) 原理 计算当前学校的票数,暂且记作a 计算票数大于自己的学校数目,暂且记作b,如果b=0,则自己票数排名第一 计算票数小于自己的学校数目,暂且记作c,如果c=0,则自己票数排名最后 如果b!=0c!=0,那么b+c就是
MySQL存储过程获取记录排名(一般用于投票系统)原理
计算当前学校的票数,暂且记作a
计算票数大于自己的学校数目,暂且记作b,如果b=0,则自己票数排名第一
计算票数小于自己的学校数目,暂且记作c,如果c=0,则自己票数排名最后
如果b != 0 && c != 0,那么b+c就是自己的票数排名
CREATE PROCEDURE `get_rank`(IN `school` INT) BEGIN SET @votes = (SELECT COUNT(tcl_vote.vote_id) AS counts FROM tcl_works LEFT JOIN tcl_vote ON tcl_vote.works_id = tcl_works.works_id WHERE tcl_works.school_id=school); SET @gt = ( SELECT COUNT(*) FROM ( SELECT tcl_works.school_id, COUNT(tcl_vote.vote_id) AS votes FROM tcl_works LEFT JOIN tcl_vote ON tcl_vote.works_id = tcl_works.works_id GROUP BY tcl_works.school_id HAVING votes > @votes ORDER BY votes DESC ) AS xxx ); IF @gt = 0 THEN SET @rank = 1; SELECT @rank AS rank; ELSE SET @lt = ( SELECT COUNT(*) FROM ( SELECT tcl_works.school_id, COUNT(tcl_vote.vote_id) AS votes FROM tcl_works LEFT JOIN tcl_vote ON tcl_vote.works_id = tcl_works.works_id GROUP BY tcl_works.school_id HAVING votes < @votes ORDER BY votes DESC ) AS xxx ); IF @lt = 0 THEN SET @rank =(SELECT COUNT(*) FROM tcl_school LIMIT 1); SELECT @rank AS rank; ELSE SET @rank = (@gt+@lt); SELECT @rank AS rank; END IF; END IF; END; call get_rank(1)

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