sql查询语句按条件统计字段值并在一个表中多列显示
例如这样的表：
count con1 con2
10 1 2
20 1 1
221 2 2
32 2 1
con1和con2为条件，count为库存数量（可以理解为con1代表厂家代码，例如1为三星，2为苹果， con2为产品代码，2为台式机，1为笔记本。）
要做如下查询并生成这样的库存统计表：
三星笔记本 三星台式机 苹果笔记本 苹果台式机
20 10 32 221
语句如何写？
oracle数据库，
select sum(case
when con1 = 1 and con2 = 1 then
count
else
0
end) 三星笔记本,
sum(case
when con1 = 1 and con2 = 2 then
count
else
0
end) 三星台式机,
sum(case
when con1 = 2 and con2 = 1 then
count
else
0
end) 苹果笔记本,
sum(case
when con1 = 2 and con2 = 2 then
count
else
0
end) 苹果台式机
from table_name;
when con1 = 1 and con2 = 1 then
count
else
0
end) 三星笔记本,
sum(case
when con1 = 1 and con2 = 2 then
count
else
0
end) 三星台式机,
sum(case
when con1 = 2 and con2 = 1 then
count
else
0
end) 苹果笔记本,
sum(case
when con1 = 2 and con2 = 2 then
count
else
0
end) 苹果台式机
from table_name;
温馨提示：内容为网友见解，仅供参考
第1个回答 推荐于2017-11-26
select sum(case when con1||con2='11' then count else 0 end) 三星笔记本,
sum(case when con1||con2='12' then count else 0 end) 三星台式机,
sum(case when con1||con2='22' then count else 0 end) 苹果笔记本,
sum(case when con1||con2='22' then count else 0 end) 苹果台式机
from table_name
另外用decode一样可以替代case when,效率一样本回答被提问者和网友采纳
sum(case when con1||con2='12' then count else 0 end) 三星台式机,
sum(case when con1||con2='22' then count else 0 end) 苹果笔记本,
sum(case when con1||con2='22' then count else 0 end) 苹果台式机
from table_name
另外用decode一样可以替代case when,效率一样本回答被提问者和网友采纳
第2个回答 2014-01-17
select case when t.con1=1 and t.con2=1 then t.count else 0 end as '三星笔记本'，
case when then else end from 表名字 t
就照这样写
case when then else end from 表名字 t
就照这样写
第3个回答 2014-01-17
group by 按 con1 con2 分组 然后sum
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