Question

i’m starter in linq, i have write this T-SQL Query

select * from DOCUMENT_TYPES where document_id in(
select document_id from Clearance_Document where Clearance_id=(select clearance_id from clearance_id from request where request_id=3)) 

i want convert this T-SQL Query to linq, please help me, thanks

Answer 1

Well, I would start first by refactoring your SQL into something other than a chain of nested sub-queries. I think this ought to do the same thing, and it’s much more readable:

SELECT
    *
FROM
    DOCUMENT_TYPES dt
JOIN
    Clearance_Document cd
    ON
    dt.document_id = cd.document_id
JOIN
    Request r
    ON
    cd.clearance_id = r.clearance_id
WHERE 
    r.request_id = 3

(I’m assuming that from clearance_id from request was a typo.)

Then you can easily refactor into a LINQ statement:

var result = from dt in DOCUMENT_TYPES
             join cd in Clearance_Document on dt.document_id equals cd.document_id
             join r in Request on cd.clearance_id equals r.clearance_id
             where r.request_id = 3
             select new {
                property1 = dt.something,
                property2 = cd.somethingElse,
                ...
             };