How to join 2 IQuerables

Question

User-222276809 posted

I have 2 queries which have same table joins but different where conditions. I need to compare the result of these 2 queries. Instead of saying .ToList() on each query and getting the result into memory and comparing can I join these 2 IQuerables and then perform the comparison? My goal is to hit DB only once. Please help!!

Answer 1

User283571144 posted

Hi praveen_katta,

According to your description, I suggest you could write a sql query to select the result which you want instead of using linq to get the result.

I suggest you could refer to below query example:

Select  * FROM 
(
QUERY A GOES HERE 
) AS A
LEFT JOIN
(
QUERY B GOES HERE 
) AS B
ON A.Col1=B.Col1 AND A.Col2=B.Col2 ....

Best Regards,

Brando

Answer 2

User1120430333 posted

If you close the connection after you do the ToList(), then you have disconnected objects in the LIst<T>. As the objects are iterated over with a loop within the List<T> as an example, the objects are not populated again from the database, because the objects are disconnected.