Mysql-如何将列的值分组到最小-最大范围?
我可以将另一列的值分组到多个范围定义中吗 下面是一个示例表:Mysql-如何将列的值分组到最小-最大范围?,mysql,Mysql,我可以将另一列的值分组到多个范围定义中吗 下面是一个示例表: mysql> select * from t; +------+------+ | x | y | +------+------+ | 1 | 1 | | 2 | 1 | | 3 | 1 | | 4 | 2 | | 5 | 2 | | 6 | 2 | | 7 | 1 | | 8 | 1 | | 9 | 1 |
mysql> select * from t;
+------+------+
| x | y |
+------+------+
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 2 |
| 6 | 2 |
| 7 | 1 |
| 8 | 1 |
| 9 | 1 |
+------+------+
我想选择以下信息:y=1
具有x的范围:1-3、7-9
,y=2
具有范围:4-6
定义和数据:
create table t (x int, y int);
insert into t(x,y) values (1,1),(2,1),(3,1),(4,2),(5,2),(6,2),(7,1),(8,1),(9,1);
试试这个:
SELECT y,group_concat(xr) FROM (
SELECT y,
CASE WHEN min(x)=max(x) THEN CAST(min(x) as char(8))
ELSE concat(CAST(min(x) AS char(8)),'-',CAST(max(x) AS char(8)))
END xr, g FROM (
SELECT y,x, CASE WHEN @g=@c AND x=@l+1
THEN @g ELSE @c:=@g:=@g+1 END g ,
@l:=x lastx
FROM tab,( SELECT @g:=0, @c:=-1, @l=-1 ) vars
ORDER BY y,x
) grp1
GROUP BY y,g
) grp2 GROUP BY y
使用的变量:
@g group counter
@c current x value
@l previous ('last') x value
我还修复了每组单个项目的问题
请参见此处了解工作小提琴:如果x是连续序列(无间隙),则可以执行以下操作:
SELECT a.y
, a start
, MIN(c.x) end
FROM t a
LEFT
JOIN t b
ON b.y = x.y
AND b.x = a.x - 1
LEFT
JOIN tbl c
ON c.y = a.y
AND c.x >= a.x
LEFT
JOIN t d
ON d.y = a.y
AND d.x = c.x + 1
WHERE b.x IS NULL
AND c.x IS NOT NULL
AND d.x IS NULL
GROUP
BY a.y,a.x;
如果不是,那么你可以这样做:
SELECT a.y
, a.x start
, MIN(c.x) end
FROM (SELECT *,@a:=@a+1 rank FROM t,(SELECT @a:=0) vars ORDER BY x) a
LEFT
JOIN (SELECT *,@b:=@b+1 rank FROM t,(SELECT @b:=0) vars ORDER BY x) b
ON b.y = a.y
AND b.rank = a.rank - 1
LEFT
JOIN (SELECT *,@c:=@c+1 rank FROM t,(SELECT @c:=0) vars ORDER BY x) c
ON c.y = a.y
AND c.rank >= a.rank
LEFT
JOIN (SELECT *,@d:=@d+1 rank FROM t,(SELECT @d:=0) vars ORDER BY x) d
ON d.y = a.y
AND d.rank = c.rank + 1
WHERE b.x IS NULL
AND c.x IS NOT NULL
AND d.x IS NULL
GROUP
BY a.y,a.x;
但是,对于较大的数据集,这两种查询都会很慢。这就是说,第二个解决方案中包含的一个想法可以适用于性能是一个问题的情况——很好,类似于cars10的解决方案。因此,您希望找到序列的开始和结束。@当然,如果您只是运行此
从t group by y中选择y,min(x),max(x)代码>查询,它将显示y=1的最小值是1,最大值是9,这是正确的,但不是我想要的。x是连续序列吗?@草莓,不,不是