MySQL实现排名并查询指定用户排名功能,并列排名功能
表结构:
CREATE TABLE test.testsort ( id int(11) NOT NULL AUTO_INCREMENT, uid int(11) DEFAULT 0 COMMENT '用户id', score decimal(10, 2) DEFAULT 0.00 COMMENT '分数', PRIMARY KEY (id) ) ENGINE = INNODB AUTO_INCREMENT = 1 CHARACTER SET utf8 COLLATE utf8_general_ci COMMENT = '测试排序' ROW_FORMAT = DYNAMIC;
思路:可以先排序,再对结果进行编号;也可以先查询结果,再排序编号。
说明:
@rownum := @rownum + 1 中 := 是赋值的作用,这句话的意思是先执行@rownum + 1,然后把值赋给@rownum;
(SELECT @rownum := 0) r 这句话的意思是设置rownum字段的初始值为0,即编号从1开始。
实现排名:
方法一:
SELECT t.*, @rownum := @rownum + 1 AS rownum FROM (SELECT @rownum := 0) r, (SELECT * FROM testsort ORDER BY score DESC) AS t;
方法二:
SELECT t.*, @rownum := @rownum + 1 AS rownum FROM (SELECT @rownum := 0) r, testsort AS t ORDER BY t.score DESC;
结果:
查看指定用户排名:
方法一:
SELECT b.* FROM (SELECT t.*, @rownum := @rownum + 1 AS rownum FROM (SELECT @rownum := 0) r, (SELECT * FROM testsort ORDER BY score DESC) AS t) AS b WHERE b.uid = 222;
方法二:
SELECT b.* FROM (SELECT t.*, @rownum := @rownum + 1 AS rownum FROM (SELECT @rownum := 0) r, testsort AS t ORDER BY t.score DESC) AS b WHERE b.uid = 222;
结果:
实现并列排名(相同分数排名相同):
SELECT obj.uid, obj.score, CASE WHEN @rowtotal = obj.score THEN @rownum WHEN @rowtotal := obj.score THEN @rownum := @rownum + 1 WHEN @rowtotal = 0 THEN @rownum := @rownum + 1 END AS rownum FROM (SELECT uid, score FROM testsort ORDER BY score DESC) AS obj, (SELECT @rownum := 0, @rowtotal := NULL) r
查询指定用户并列排名:
SELECT total.* FROM (SELECT obj.uid, obj.score, CASE WHEN @rowtotal = obj.score THEN @rownum WHEN @rowtotal := obj.score THEN @rownum := @rownum + 1 WHEN @rowtotal = 0 THEN @rownum := @rownum + 1 END AS rownum FROM (SELECT uid, score FROM testsort ORDER BY score DESC) AS obj, (SELECT @rownum := 0, @rowtotal := NULL) r) AS total WHERE total.uid = 222;
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