现有一张表名为T,共有四个字段(C1,C2,C3,C4),有如下数据
C1 C2 C3 C4A A C B
C D B A
D A C B
C C B A
A D C A
D C A B
B A D A
C A D D
D C B A要求用SQL语句进行统计,实现如下输出Alphabet CountNum
A 12
B 7
C 9
D 8
C1 C2 C3 C4A A C B
C D B A
D A C B
C C B A
A D C A
D C A B
B A D A
C A D D
D C B A要求用SQL语句进行统计,实现如下输出Alphabet CountNum
A 12
B 7
C 9
D 8
from
(select c1 from T
union
select c2 from T
union
select c3 from T
union
select c4 from T) as A
group by c1
是不能统计出来的字段的值 是在不同的数据列中
(
C1 varchar(10),
C2 varchar(10),
C3 varchar(10),
C4 varchar(10)
)insert into T values('A','A','C','B')
insert into T values('C','D','B','A')
insert into T values('D','A','C','B')
insert into T values('C','C','B','A')
insert into T values('A','D','C','A')
insert into T values('D','C','A','B')
insert into T values('B','A','D','A')
insert into T values('C','A','D','D')
insert into T values('D','C','B','A')select c1 as Alphabet , count(c1) AS CountNum
from
(select c1 from T
union all
select c2 from T
union all
select c3 from T
union all
select c4 from T) as A
group by c1