I have two tables, Table1
and Table2
. I want to perform, say, a left outer join:
var myOutput = from object1 in Table1
join object2 in Table2
on object1.Property1 equals object2.Property2 into Table3
from output in Table3.DefaultIfEmpty()
select new
{
object1.Property1,
object1.Property2,
//...
output.Property3,
output.Property4,
//...
};
As you can notice, I want to select all the properties of both objects from the resulting table (the enumerables considered while joining contain the objects of certain types - these are different for both relations). Of course, I can select the properties in the anonymous select, as shown in the example.
My question is how to avoid specifying all the properties manually? I would like to have something like SELECT * FROM TABLE3
, where TABLE3
is a resulting relation (after joining TABLE1
and TABLE2
).
Thanks in advance for the clues.
LINQ Inner Join Sometimes, it is required to send data from two or more tables or objects in a single unit based on your provided information. Inner Join produces the result from two or more than two tables. So, basically we are meant to get the records from both tables based on matching conditions.
Examples include listing all Customers with their SalesOrders, including Customers that don't have a SalesOrder, and listing all Customers who don't have a SalesOrder. To meet these requirements you need to use the LINQ Join clause.
There are different types of join in SQL and these are Inner Join, Left Outer Join, Right Outer Join, Full Outer Join, and Cross Join. But after introducing Linq with C# 3.0, there were huge changes in the programming world. Now, most of the developers use Linq for getting the data from the object. Linq stands for Language Integrated Query.
The following is the Linq query for the above SQL query. It includes all rows from the left table and matching rows from the right table. We process the query with some condition which contains the unique column in both tables.
You have to specify each manually if you want to project into a flattened type. Your other option is to just have your combined type contain both objects, and the objects will naturally bring along their properties.
select new
{
Object1 = object1,
Object2 = output
};
And you would work with it like myObj.Object1.Property1
, myObj.Object2.Property4
, etc.
One final option that still involves some manual work is to define an appropriate type and have a constructor or a builder method that does the work of segmenting out your object properties into a flattened type. You still perform the manual mapping, but you isolate it from your query logic.
select new CombinedType(object1, output);
//or
select builder.GetCombinedType(object1, output);
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