Question

这让我完全难过。从一组数字 - 对于这个例子1到20，我正在尝试做上一个和下一个链接，所以他们最终会这样：我将提供从头开始的数字。

1       6           11          16
2       7           12          17
3       8           13          18
4       9           14          19
5       10          15          20
n-5    p-6 n-10   p-11 n-15    p-16

你知道如何为这样的事做sql吗？

我试图在这个基础上建立，但没有运气：

SELECT c.id,
  (SELECT MAX(p.id) FROM mytable p WHERE p.id < c.id AND p.country = 'us') prev_id,
  (SELECT MIN(n.id) FROM mytable n WHERE n.id > c.id AND n.country = 'us') next_id
FROM mytable as c WHERE c.id = 5;

表格数据

    "id"    "country"
"1"     "US"
"2"     "US"
"3"     "US"
"4"     "US"
"5"     "US"
"6"     "US"
"7"     "US"
"8"     "US"
"9"     "US"
"10"    "US"
"11"    "US"
"12"    "US"

所需的输出

我提供的数字= 10

prev  | next
-------------
6     | 10

Answer 1

以下是MySQL解决方案：

SET @number=15;
SET @counter=0;


SELECT x.id, @number as next
FROM (
SELECT id, (@counter:=@counter+1) as line FROM TableData WHERE id <=@number ORDER BY id 
) x
WHERE x.line = @counter-5;

number是您指定的内容。

您可以在SQL Fiddle中查看其工作原理。随意更改其数据和测试，

用于在MySql中生成上一个和下一个链接的Sql

1 个答案: