Question

我的表

+------+-------+--------+
| NAME | MARKS | POINTS |
+------+-------+--------+
| S1   |    53 | (null) |
| S2   |    55 | (null) |
| S3   |    56 | (null) |
| S4   |    55 | (null) |
| S5   |    52 | (null) |
| S6   |    51 | (null) |
| S7   |    53 | (null) |
+------+-------+--------+

参考：http://www.sqlfiddle.com/#!2/5d046/1

我想在最高分上加3,2,1分。这里S3到3点，S2，S4到2点，S1，S7到1点。

最终输出看起来，

+------+-------+--------+
| NAME | MARKS | POINTS |
+------+-------+--------+
| S1   |    53 |   1    |
| S2   |    55 |   2    |
| S3   |    56 |   3    |
| S4   |    55 |   2    |
| S5   |    52 |   0    |
| S6   |    51 |   0    |
| S7   |    53 |   1    |
+------+-------+--------+

Plz帮助

Answer 1

我的建议是，您首先计算每个标记的排名，然后在更新中的案例陈述中使用它。

以下查询显示了计算排名的一种方法：

select t.*,
       @rn := if(@marks = marks, @rn, @rn + 1) as ranking,
       @marks := marks
from myTable t cross join
     (select @rn := 0, @marks := -1) const
order by t.marks desc;

（注意：我对这个方法有点不舒服，因为MySQL不保证用常量评估两个表达式的顺序。如果在@marks之前设置@rn，那么它在实践中，这似乎不会发生。并且，这与相关子查询的等价物更有效。）

然后，您可以使用update：

将其加入join

update myTable join
       (select t.*,
               @rn := if(@marks = marks, @rn, @rn + 1) as ranking,
               @marks := marks
        from myTable t cross join
             (select @rn := 0, @marks := -1) const
        order by t.marks desc
       ) mr
       on myTable.Name = mr.Name
    set myTable.Points := (case when mr.ranking = 1 then 3
                                when mr.ranking = 2 then 2
                                when mr.ranking = 3 then 1
                                else 0
                           end);

已在您的SQL Fiddle上测试过。

Answer 2

UPDATE myTable t1
INNER JOIN 
(
SELECT @row:=@row-1 AS RowPoints, Marks
FROM (
  SELECT Marks
  FROM myTable
  GROUP BY Marks
  ORDER BY Marks DESC
  LIMIT 3
) AS TopMarks
INNER JOIN (SELECT @row:=4) AS RowInit
) AS AddPoints ON t1.Marks = AddPoints.Marks
SET Points = COALESCE(Points, 0) + AddPoints.RowPoints;

这应该可以正常工作。您应该并且在Marks列上进行索引。

Answer 3

您可以通过变量（请参阅其他答案中的示例）或case：

来完成

select 
  myTable.*,
  case
    when max1.marks is not null then 3
    when max2.marks is not null then 2
    when max3.marks is not null then 1
    else 0
  end as score
from
  myTable
  LEFT JOIN
  (select marks from myTable order by marks desc limit 1) AS max1
  ON myTable.marks=max1.marks
  LEFT JOIN
  (select marks from myTable order by marks desc limit 2,1) AS max2
  ON myTable.marks=max2.marks
  LEFT JOIN
  (select marks from myTable order by marks desc limit 3,1) AS max3
  ON myTable.marks=max3.marks;

可以找到演示here。

Answer 4

最简单的方法：

SELECT t.Name Name, t.Marks Marks,

 (CASE WHEN Marks = (Select max(marks) from mytable) THEN 3 ELSE 0 END+

CASE WHEN Marks = (Select min(marks) from (Select distinct marks 
    from mytable order by marks desc limit 2) a) THEN 2 ELSE 0 END+

CASE WHEN Marks = (Select min(marks) from (Select distinct marks 
    from mytable order by marks desc limit 3) b) THEN 1 ELSE 0 END)

AS `Points`
FROM mytable t;

<强> SQL Fiddle

Mysql中最高记录点数

4 个答案: