[ACCEPTED]-linq to sql: join multiple columns from the same table-join
This is the only way I was able to get it 1 to work (in c#).
var qry = from t1 in table1
join t2 in table2
on new {t1.ID,t1.Country} equals new {t2.ID,t2.Country}
...
You can put your query inside a Where clause 4 instead of using the join operator.
The join 3 operator supports multiple clauses in VB.NET, but 2 not C#.
Alternatively, you can use the ANSI-82 1 style of 'SQL' syntax, e.g.:
from t1 in table1
from t2 in table1
where t1.x == t2.x
&& t1.y == t2.y
from http://www.onedotnetway.com/linq-to-sql-join-on-multiple-conditions/
Both these tables have PostCode and 6 CouncilCode as common fields. Lets say that 5 we want to retrieve all records from ShoppingMall 4 where both PostCode and CouncilCode on House 3 match. This requires us to do a join using 2 two columns. In LINQ such a join can be 1 done using anonymous types. Here is an example.
var query = from s in context.ShoppingMalls
join h in context.Houses
on
new { s.CouncilCode, s.PostCode }
equals
new { h.CouncilCode, h.PostCode }
select s;
var query = from s in context.ShoppingMalls
join h in context.Houses
on
new {CouncilCode=s.CouncilCode, PostCode=s.PostCode }
equals
new {CouncilCode=h.District, PostCode=h.ZipCode }
select s;
This is applicable for any kind of datatype.
0
In VB:
dim qry = FROM t1 in table1 _
JOIN t2 in table2 on t2.ID equals t1.ID _
AND t2.Country equals t1.Country
0
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