行转列，列转行，传统方式与pivot方式，不同的实现，同样的结果
最近在做考勤管理，有需要行转列的报表，CaseWhen老方法可以实现，但Pivot方法实现更为简便，以下是具体实现。
1 --行转列
2 create table T_1(Name varchar(10),LeaveType varchar(10), Days int)
3
4 insert into T_1 values('张三丰','病假',20)
5 insert into T_1 values('张无忌','婚假',3)
6 insert into T_1 values('萧峰','探亲假',30)
7 insert into T_1 values('段誉','事假',2)
8 insert into T_1 values('虚竹','事假',3)
9
10 select * from T_1
11
12 --case when 老用法
13 select Name,
14
15 max(case LeaveType when '病假' then Days else 0 end) 病假,
16 max(case LeaveType when '婚假' then Days else 0 end) 婚假,
17 max(case LeaveType when '探亲假' then Days else 0 end) 探亲假,
18 max(case LeaveType when '事假' then Days else 0 end) 事假
19 from T_1
20 group by Name
21
22 --case when 动态老用法
23 declare @sqlstr varchar(600)
24
25 set @sqlstr='select Name'
26 select @sqlstr=@sqlstr+',max(case LeaveType when '''+LeaveType+''' then Days else 0 end) ['+LeaveType+']'
27 from(select distinct LeaveType from T_1) a
28 set @sqlstr=@sqlstr+ ' from T_1 group by Name'
29 exec(@sqlstr)
30
31 -- 使用新用法pivot
32 select * from T_1 pivot(max(Days) for LeaveType in (病假,婚假,探亲假,事假)) a
33
34 --使用新用法pivot动态
35
36 declare @sqlstr varchar(6000)
37
38 set @sqlstr=''
39 select @sqlstr=@sqlstr+','+LeaveType from T_1 group by LeaveType
40 set @sqlstr=stuff(@sqlstr,1,1,'')
41 set @sqlstr='select * from T_1 pivot (max(Days) for LeaveType in ('+@sqlstr+')) a'
42 exec(@sqlstr)
43
44 --列转行
45
46 create table T_2(Name varchar(10),病假 int,婚假 int,事假 int, 探亲假 int)
47
48 insert into T_2 values('段誉',0,0,2,0)
49 insert into T_2 values('萧峰',0,0,0,30)
50 insert into T_2 values('虚竹',0,0,3,0)
51 insert into T_2 values('张三丰',20,0,0,0)
52 insert into T_2 values('张无忌',0,3,0,0)
53
54 select * from T_2
55
56 --老方法 case when
57 select * from(
58 select Name,LeaveType='病假',Days=病假 from T_2
59 union all
60 select Name,LeaveType='婚假',Days=婚假 from T_2
61 union all
62 select Name,LeaveType='事假',Days=事假 from T_2
63 union all
64 select Name,LeaveType='探亲假',Days=探亲假 from T_2) t
65 where t.Days <> 0
66 order by Name
67
68 --老方法 case when 动态
69
70 declare @sqlstr varchar(6000)
71 select @sqlstr= isnull(@sqlstr+' union all ','')+' select Name, [LeaveType]='
72 +quotename(Name,'''')+' , [Days] = '+quotename(Name)+' from T_2'
73 from syscolumns
74 where Name!='Name' and ID=object_id('T_2') --表名tb，不包含列名为姓名的其他列
75 order by colid
76 exec('select * from ('+@sqlstr+')t where Days <> 0 order by Name')
77
78 select * from syscolumns where ID=object_id('T_2')
79
80 --新方法 pivot
81
82 select * from T_2
83
84 select Name,LeaveType,Days from T_2 unpivot (Days for LeaveType in([病假],[婚假],[事假],[探亲假])) t
85 where days <> 0
86
87 --新方法 pivot 动态
88
89 declare @sqlstr varchar(6000)
90 select @sqlstr=isnull(@sqlstr+',','')+quotename(Name)
91 from syscolumns
92 where ID=object_id('T_2')and Name not in('Name')
93 order by Colid
94 set @sqlstr='select Name,[LeaveType],[Days] from T_2 unpivot ([Days] for [LeaveType] in('+@sqlstr+')) b where days<> 0'
95 exec(@sqlstr)
来源：https://www.cnblogs.com/JJ.Net/p/4221928.html