Question

这是我现有的表格

 id   name  version
| 1 |  a   | 1.1 |
| 2 |  b   | 2.1 |
| 3 |  c   | 3.1 |
| 4 |  d   | 1.2 |
| 5 |  e   | 4.1 |

如何编写查询以生成结果，其中我将返回所有记录，但只选择列版本中的最后一条记录，如下所示？

 id   name  version
| 4 |  d   | 1.2 |
| 2 |  b   | 2.1 |
| 3 |  c   | 3.1 |
| 5 |  e   | 4.1 |

Answer 1

如果您更喜欢稍微费力的解决方案......

SELECT x.*
  FROM t x
  JOIN 
     ( SELECT MAX(grade) grade
         FROM t
        GROUP 
           BY FLOOR(grade)
     ) y
    ON y.grade = x.grade

http://sqlfiddle.com/#!9/f17db1/16

Answer 2

这有点费力，但可以做到

SELECT
  SUBSTRING_INDEX(GROUP_CONCAT(id ORDER BY REPLACE(grade,'.','')*1 DESC),',',1) as id,
  SUBSTRING_INDEX(GROUP_CONCAT(letter ORDER BY REPLACE(grade,'.','')*1 DESC),',',1) as letter,
  MAX(grade) as grade
FROM
  t
  GROUP BY SUBSTRING_INDEX(grade,'.',1)
  ORDER BY REPLACE(grade,'.','')*1

假设最后一列是浮动的，你可以直接使用ORDER BY lastcol

FIDDLE

CREATE TABLE t
    (`id` int, `letter` varchar(7), `grade` varchar(55))
;

INSERT INTO t

VALUES
    (1, 'a', '1.1'),
    (2, 'b', '2.1'),
    (3, 'c', '3.1'),
    (4, 'd', '1.2'),
    (5, 'e', '4.1')

仅从列中获取最后一条mysql记录

2 个答案: