Question

例如csv中的数据是

#row, col, number
y1,x1,1
y2,x2,1
y2,x2,1
y2,x3,1

如果我使用简单的组SQL，它可以显示为一维

select y1,x1,count(*) from data group by 1,2 order by 1,2

1-D结果是

row col count(*)
y1  x1  1
y2  x2  2
y2  x3  3

我想表现出像

row x1 x2 x3
y1   1  0 0
y2   0  2 1

如果col仅限于＆x;＆＃39; x2＆＃39; x3＆＃39; x3＆＃39;，则可以使用一个SQL显示为2-D ？

Answer 1

SELECT row,
SUM(CASE WHEN col= 'x1' THEN 1 else 0 END) AS x1,
SUM(CASE WHEN col= 'x2' THEN 1 else 0 END) AS x2,
SUM(CASE WHEN col= 'x3' THEN 1 else 0 END) AS x3
FROM data 
GROUP BY row;

Answer 2

试试这个

sql fiddle

select row,isnull(sum(x2),0) as X2,isnull(sum(x3),0) as X3
from(select row,case when col = 'x1'
then
cnt 
end as x1,
case when col = 'x2'
then
cnt 
end as x2,
case when col = 'x3'
then
cnt
end as x3
from
(select row,col,count(*) as cnt from test1 group by row,col ) as test)
as total
group by row

如何用一个SQL在2-D中显示x，y，count（*）？

2 个答案: