Question

我有一张像下面这样具有巨大价值的桌子。＆＃39; FBB＆＃39;类型值将在稍后的表的SERVICE列中添加。

SITE_NAME  SERVICE  BANDWIDTH
MBCGP1     3g       30
BONWRT     3g       40
BORNR1     3g       30
MBCGP1     2g       8
BONWRT     2g       4
BORNR1     2g       8
BOSBB1     2g       8

我想在这样的表中插入这些值。

SITE_NAME  2g_bw  3g_bw  fbb_bw
MBCGP1     8       30     0
BONWRT     4       40     0
BORNR1     8       30     0
BOSBB1     8       0      0

我不知道如何编写一个sql。

Answer 1

您可以将表的实例用于2g，将另一个用于3g，然后将这些表连接起来。

select 2g.site_name, 2g.bandwidth 2g_bw, 3g.bandwidth 3g_bw, 0 fbb_bw
from yourtable 2g
join yourtable 3g
  on 3g.site_name = 2g.site_name
 and 3g.service = '3g'
where 2g.service = '2g'

然后，您可以将结果插入另一个包含INSERT ... SELECT

的表格中

insert into othertable (site_name, 2g_bw, 3g_bw, fbb_bw)
select 2g.site_name, 2g.bandwidth 2g_bw, 3g.bandwidth 3g_bw, 0 fbb_bw
from yourtable 2g
join yourtable 3g
  on 3g.site_name = 2g.site_name
 and 3g.service = '3g'
where 2g.service = '2g'

更新

正如@Strawberry建议的那样，你可以使用完全连接来获得2g或3g（不是两者）的空值。

select 2g.site_name, 2g.bandwidth 2g_bw, 3g.bandwidth 3g_bw, 0 fbb_bw
from yourtable 2g
left outer join yourtable 3g
   on 3g.site_name = 2g.site_name
  and 3g.service = '3g'
where 2g.service = '2g'
union
select 3g.site_name, 2g.bandwidth 2g_bw, 3g.bandwidth 3g_bw, 0 fbb_bw
from yourtable 3g
left outer join yourtable 2g
   on 2g.site_name = 3g.site_name
  and 2g.service = '2g'
where 3g.service = '3g'

第一个请求获得2G和3G相关的结果，第二个结果与3G和2G相关联。如果您将结果联合起来，那么肯定会检索所有结果。

如何将行转置为列

1 个答案:

更新