需要左外连接类型时在LINQ中连接表的问题

Question

I have two tables:

Network_Clients
Clients

Network_Clients has three columns

networkClientID: Key
Name: Varchar
Description: Varchar

Client has 4 columns:

clientID: Key
networkClientId: FK to Network_Clients -> networkClientID
Name: Varchar
Description: Varchar

Clients Table:

clientID    networkClientID name    description
1                2          Client1 Client of Client2
2                3          Client1 Client of Client3
3                3          Client4 Client of Client3
4                1          Client4 Direct Placement Client
5                1          Client1 Direct Placement Client

Network Clients Table:

networkClientID name            description
1           Direct Placer       NULL
2           Client2             Network Client Client2
3           Client3             Network Client Client3
4           Test One            Test One Network Client

Here is my LINQ query:

from cn in Clients_Network
join c in Clients on cn.networkClientID equals c.networkClientID
select new { cn, c }

This returns everything but Direct Placer and Test One because neither of those have a linked field in the Clients table.

How can I get those two to show up?

Answer 1

Use group join (ie join...into):

from cn in Clients_Network
join c in Clients on cn.networkClientID equals c.networkClientID into g
from cc in g.DefaultIfEmpty()
select new { cn, cc }

Thats an equivalent of left join in SQL