如何实现横向聚合
问题描述：
有表tb，数据如下
A<chmetcnv w:st="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="1" unitname="a">1 A</chmetcnv><chmetcnv w:st="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="2" unitname="a">2 A</chmetcnv><chmetcnv w:st="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="3" unitname="a">3 A</chmetcnv><chmetcnv w:st="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="4" unitname="a">4 A</chmetcnv>5
1 2 5 3 4
2 2 3 4 5
0 3 4 2 5
如何输出
A<chmetcnv w:st="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="1" unitname="a">1 A</chmetcnv><chmetcnv w:st="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="2" unitname="a">2 A</chmetcnv><chmetcnv w:st="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="3" unitname="a">3 A</chmetcnv><chmetcnv w:st="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="4" unitname="a">4 A</chmetcnv>5 最大 最小 5以上个数
1 2 5 3 4 5 1 1
2 2 3 4 5 5 2 1
0 3 5 2 6 6 0 2
答：
SQL Server的聚合函数是在列上的，所以可以写自定义的函数，也可以想办法把列变为行，再用聚合函数处理
解决示例
--测试数据
DECLARE @t TABLE(A1 int, A2 int, A3 int, A4 int, A5 int)
INSERT @t SELECT 1,2,5,3,4
<place w:st="on"><span lang="EN-US" style='FONT-SIZE: 9pt; COLOR: blue; FONT-FAMILY: "Courier New"; mso-font-kerning: 0pt; mso-no-proof: yes'>UNION</span></place> ALL SELECT 2,2,3,4,5
<place w:st="on"><span lang="EN-US" style='FONT-SIZE: 9pt; COLOR: blue; FONT-FAMILY: "Courier New"; mso-font-kerning: 0pt; mso-no-proof: yes'>UNION</span></place> ALL SELECT 0,3,4,2,5
--查询
SELECT *,
[min] = (
SELECT MIN(v) FROM(
SELECT v=A.A1 UNION SELECT v=A.A2 UNION SELECT v=A.A3
UNION SELECT v=A.A4 UNION SELECT v=A.A5
)B),
[max] = (
SELECT MAX(v) FROM(
SELECT v=A.A1 UNION SELECT v=A.A2 UNION SELECT v=A.A3
UNION SELECT v=A.A4 UNION SELECT v=A.A5
)B),
[count>=5] = (
SELECT COUNT(*) FROM(
SELECT v=A.A1 UNION SELECT v=A.A2 UNION SELECT v=A.A3
UNION SELECT v=A.A4 UNION SELECT v=A.A5
)B WHERE v>=5)
FROM @t A
查询结果:
A<chmetcnv w:st="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="1" unitname="a">1<span style="mso-spacerun: yes"> </span>A</chmetcnv><chmetcnv w:st="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="2" unitname="a">2<span style="mso-spacerun: yes"> </span>A</chmetcnv><chmetcnv w:st="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="3" unitname="a">3<span style="mso-spacerun: yes"> </span>A</chmetcnv><chmetcnv w:st="on" tcsc="0" numbertype="1" negative="False" hasspace="True" sourcevalue="4" unitname="a">4<span style="mso-spacerun: yes"> </span>A</chmetcnv>5 min max count>=5
----------- ----------- ----------- ----------- ----------- ----------- -----------
1 2 5 3 4 1 5 1
2 2 3 4 5 2 5 1
0 3 4 2 5 0 5 1