Question

我是SQL新手。我正在寻找一个简单的SQL解决方案来组合行/列，其行包含相同的数据，在本例中为邮政编码。例如，数据看起来像这样：

state, county, city, zip, count

"CA","ALAMEDA","HAYWARD","94541",5371
"CA","ALAMEDA","HAYWARD","94542",2209
"CA","ALAMEDA","HAYWARD","94544",7179
"CA","ALAMEDA","HAYWARD","94545",4209
"CA","ALAMEDA","CASTRO VALLEY","94546",7213
"CA","ALAMEDA","HAYWARD","94546",37
"CA","ALAMEDA","LIVERMORE","94550",9809
"CA","ALAMEDA","LIVERMORE","94551",6558
"CA","ALAMEDA","CASTRO VALLEY","94552",3121
"CA","ALAMEDA","HAYWARD","94552",12
"CA","ALAMEDA","FREMONT","94555",5392

我想最终将数据看起来像这样：

state, county, city, zip, count

"CA","ALAMEDA","HAYWARD","94541",5371
"CA","ALAMEDA","HAYWARD","94542",2209
"CA","ALAMEDA","HAYWARD","94544",7179
"CA","ALAMEDA","HAYWARD","94545",4209
"CA","ALAMEDA","CASTRO VALLEY / HAYWARD","94546",7250
"CA","ALAMEDA","LIVERMORE","94550",9809
"CA","ALAMEDA","LIVERMORE","94551",6558
"CA","ALAMEDA","CASTRO VALLEY HAYWARD","94552",3133
"CA","ALAMEDA","FREMONT","94555",5392

您可以看到，在两行中数据已合并或汇总。对于包含完全相同的邮政编码的行，城市名称（两者）都显示在城市列中，而计数是每行的计数总和。

有没有办法用SQL做到这一点？即使它需要两个不同的SQL语句也没问题。

Answer 1

假设SQL Server，您可以使用FOR XML来获得所需的结果。

select distinct t.state,t.county,t.zip,t2.sumcount,
STUFF(
        (
            SELECT '/' + city AS [text()]
            FROM mytable t3
            WHERE t.zip = t3.zip
            FOR XML PATH('')
        ), 1, 1, '') AS ColList
from mytable t 
  join (select zip, sum(count) as sumcount
       from mytable
       group by zip) t2 on t.zip=t2.zip

还有一些SQL Fiddle。

如果您使用的是MySQL，请查看使用GROUP_CONCAT：

select distinct t.state,t.county,t.zip,t2.sumcount,
GROUP_CONCAT(t.city) as cities
from mytable t 
  join (select zip, sum(count) as sumcount
       from mytable
       group by zip) t2 on t.zip=t2.zip
GROUP BY t.state,t.county,t.zip,t2.sumcount

更多Fiddle。

祝你好运。

Answer 2

我调整了sgeddes的精湛答案，实际得到了计数并避免重复输入，并添加了一个支持脚本，以便您可以测试它。这确实假定SQL Server。

IF EXISTS(SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME = 'MYTABLE') BEGIN
  drop table MYTABLE;
END;
go

create table MYTABLE
(
  state nvarchar(2)
 ,county nvarchar(100)
 ,city nvarchar(100)
 ,zip nvarchar(10)
)
go

insert into MYTABLE(state,county,city,zip) values('CA','ALAMEDA','HAYWARD','94541');
insert into MYTABLE(state,county,city,zip) values('CA','ALAMEDA','HAYWARD','94541');
insert into MYTABLE(state,county,city,zip) values('CA','ALAMEDA','HAYWARD','94544');
insert into MYTABLE(state,county,city,zip) values('CA','ALAMEDA','HAYWARD','94545');
insert into MYTABLE(state,county,city,zip) values('CA','ALAMEDA','CASTRO VALLEY','94546');
insert into MYTABLE(state,county,city,zip) values('CA','ALAMEDA','CASTRO VALLEY','94546');
insert into MYTABLE(state,county,city,zip) values('CA','ALAMEDA','CASTRO VALLEY','94546');
insert into MYTABLE(state,county,city,zip) values('CA','ALAMEDA','CASTRO VALLEY','94546');
insert into MYTABLE(state,county,city,zip) values('CA','ALAMEDA','CASTRO VALLEY','94546');
insert into MYTABLE(state,county,city,zip) values('CA','ALAMEDA','HAYWARD','94546');
insert into MYTABLE(state,county,city,zip) values('CA','ALAMEDA','HAYWARD','94546');
insert into MYTABLE(state,county,city,zip) values('CA','ALAMEDA','HAYWARD','94546');
insert into MYTABLE(state,county,city,zip) values('CA','ALAMEDA','HAYWARD','94546');
insert into MYTABLE(state,county,city,zip) values('CA','ALAMEDA','LIVERMORE','94550');
insert into MYTABLE(state,county,city,zip) values('CA','ALAMEDA','LIVERMORE','94551');
insert into MYTABLE(state,county,city,zip) values('CA','ALAMEDA','CASTRO VALLEY','94552');
insert into MYTABLE(state,county,city,zip) values('CA','ALAMEDA','HAYWARD','94552');
insert into MYTABLE(state,county,city,zip) values('CA','ALAMEDA','FREMONT','94555');

select distinct
  t.state
 ,t.county
 ,t.zip
 ,t2.sumcount
 ,STUFF((
       SELECT distinct '/' + city AS [text()]
       FROM mytable t3
       WHERE t.zip = t3.zip
       FOR XML PATH('')
       ), 1, 1, '') AS ColList
from
  mytable t 
  inner join
  (
  select zip, sum(count) as sumcount
  from
    (
    select zip,count(*) as count
    from mytable
    group by zip
    ) x
  group by zip
  ) t2
  on t.zip=t2.zip

输出如下：

state   county  zip sumcount    ColList
CA  ALAMEDA 94541   2   HAYWARD
CA  ALAMEDA 94544   1   HAYWARD
CA  ALAMEDA 94545   1   HAYWARD
CA  ALAMEDA 94546   9   CASTRO VALLEY/HAYWARD
CA  ALAMEDA 94550   1   LIVERMORE
CA  ALAMEDA 94551   1   LIVERMORE
CA  ALAMEDA 94552   2   CASTRO VALLEY/HAYWARD
CA  ALAMEDA 94555   1   FREMONT

SQL列/行分组

2 个答案: