Hive&SqlServerql:inner join on条件中如果两边都是空值的情况下,关联结果中会把数据给过滤掉。

2018/01/15 03:41
阅读数 247

今天遇到的一个大坑,话不多少,看sql和下边的查询结果:

 1 --问题:恰好把buildingid is null的记录给过滤掉
 2 create table tommyduan_gridcell_group_all_test(gridid nvarchar(32),buildingid nvarchar(32),floor nvarchar(32));
 3 insert into tommyduan_gridcell_group_all_test(gridid,buildingid,floor)values('g1',null,1);
 4 insert into tommyduan_gridcell_group_all_test(gridid,buildingid,floor)values('g2','b1',1);
 5 insert into tommyduan_gridcell_group_all_test(gridid,buildingid,floor)values('g2','b2',1);
 6 insert into tommyduan_gridcell_group_all_test(gridid,buildingid,floor)values('g3','b2',1);
 7 insert into tommyduan_gridcell_group_all_test(gridid,buildingid,floor)values('g3','b2',2);
 8 insert into tommyduan_gridcell_group_all_test(gridid,buildingid,floor)values('g3','b2',4);
 9 
10 
11 create table tommyduan_fingerlib(gridid nvarchar(32),buildingid nvarchar(32),floor nvarchar(32));
12 insert into tommyduan_fingerlib(gridid,buildingid,floor)values('g1',null,1);
13 insert into tommyduan_fingerlib(gridid,buildingid,floor)values('g2','b1',1);
14 insert into tommyduan_fingerlib(gridid,buildingid,floor)values('g2','b2',1);
15 insert into tommyduan_fingerlib(gridid,buildingid,floor)values('g3','b2',1);
16 insert into tommyduan_fingerlib(gridid,buildingid,floor)values('g3','b2',2);
17 insert into tommyduan_fingerlib(gridid,buildingid,floor)values('g3','b2',4);
18 
19 
20 select * from tommyduan_gridcell_group_all_test t10 
21 inner join tommyduan_fingerlib t11 
22 on t10.gridid=t11.gridid and t10.buildingid=t11.buildingid and t10.floor=t11.floor

查询结果:

解决方案:

 1 select * from 
 2 (
 3 select gridid,buildingid,floor,gridid+(case when buildingid is null then 'd_null' else buildingid end)+floor as tkey 
 4 from tommyduan_gridcell_group_all_test
 5 ) t10 
 6 inner join 
 7 (
 8 select gridid,buildingid,floor,gridid+(case when buildingid is null then 'd_null' else buildingid end)+floor as tkey 
 9 from tommyduan_fingerlib
10 )  t11 
11 on t10.tkey=t11.tkey

查询结果:

left outer join时的查询结果是:

1 select * from tommyduan_gridcell_group_all_test t10 
2 left outer join tommyduan_fingerlib t11 
3 on t10.gridid=t11.gridid and t10.buildingid=t11.buildingid and t10.floor=t11.floor

 

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