GROUP BY子句中的SQL Geography数据类型列

Question

我正在使用SQL Server并创建一个脚本,该脚本将从我的数据库中获取工作者的地理位置.脚本如下.

SELECT w.display_name, w.geo_location
FROM jobs j WITH(NOLOCK)
INNER JOIN workers w WITH(NOLOCK) ON w.worker_id = j.worker_id
WHERE .....

问题是我想添加GROUP BY w.display_name, w.geo_location到脚本,因为显示了重复的记录.向group by子句添加了具有数据类型geography的列会导致抛出错误.

添加此内容时抛出的错误是:

"地理"类型无法比较.它不能在GROUP BY子句中使用.

有没有解决的办法？我无法转换w.geo_location为VARCHAR地理数据类型中所需的a .

Answer 1

您可以使用row_number()类似这样的东西。

declare @g geography;
set @g = geography::STGeomFromText('LINESTRING(-122.360 47.656, -122.343 47.656)', 4326);

declare @T table
(display_name varchar(10), geo_location geography)

insert into @T values ('1', @g)
insert into @T values ('1', @g)
insert into @T values ('1', @g)

insert into @T values ('2', @g)
insert into @T values ('2', @g)

select display_name, geo_location
from 
  (
    select *,
           row_number() over(partition by display_name, geo_location.ToString() order by (select 0)) as rn
    from @T
  ) as T
where rn = 1

结果：

display_name geo_location
------------ --------------------------------------------------------------------------------
1            0xE610000001148716D9CEF7D34740D7A3703D0A975EC08716D9CEF7D34740CBA145B6F3955EC0
2            0xE610000001148716D9CEF7D34740D7A3703D0A975EC08716D9CEF7D34740CBA145B6F3955EC0

Answer 2

如果要继续使用group by语法,可以将geo列转换为text并再返回:

SELECT w.display_name, geography::STGeomFromText(w.geo_location.STAsText(), 4326) as Location
FROM jobs j WITH(NOLOCK)
INNER JOIN workers w WITH(NOLOCK) ON w.worker_id = j.worker_id
WHERE .....
GROUP BY w.display_name, w.geo_location.STAsText()