How to use the group join result to join another tables using LINQ? - sql

Question

I am not able to use the result of group join and then further applying the join with other tables.
My SQL query is :
SELECT *
FROM
[dummy_database].[dbo].[MA] M
INNER JOIN
SN.dbo.A A ON A.ApplicantMAId = M.MAId
INNER JOIN
SN.dbo.SP SP ON SP.PropertyMAId = M.MAId
INNER JOIN
SN.dbo.MCC CC ON CC.MAId = m.MAId
INNER JOIN
SN.dbo.MLSTN T ON T.MAT_ID = M.MAId
INNER JOIN
(SELECT
MAX(MAT_DATE) AS MaxDate,
MAT_ID
FROM
[SN].[dbo].[MLSTN]
GROUP BY
MAT_ID) Q ON Q.MAT_ID = M.MAId
and what I have done so far is:
var q = (from ml in context.MLSTN
group ml by ml.MAT_ID into g
let maxdate = g.Max(date => date.MAT_DATE)
select new
{
MortgId = g.Key,
TrackingDate = g.FirstOrDefault(val => val.MAT_DATE == maxdate).MAT_DATE
}
);
but now this result is not at all further used by me to create a join with other tables. I want to ask how to join further? Any clue?

Answer 1

You need something like this:
var groups = context.MLSTN
.GroupBy(x => x.MAT_ID)
.Select(g => new
{
MAT_ID = g.Key,
MaxDate = g.Max(date => date.MT_DATE)
});
var result = context.MA
.Join(context.A,
m => m.MA_ID,
a => a.MA_ID,
(m, a) => new
{
MA = m,
A = a
})
.Join(context.SP,
x => x.MA.MAId,
sp => sp.PropertyMAId,
(x, sp) => new
{
MA = x.MA ,
A = x.A,
SP = sp
})
.Join(context.MCC,
x => x.MA.MAId,
cc => cc.MAId,
(x, cc) => new
{
MA = x.MA ,
A = x.A,
SP = x.SP,
MCC = cc
})
.Join(context.MLSTN,
x => x.MA.MAId,
t => t.MAT_ID,
(x, t) => new
{
MA = x.MA ,
A = x.A,
SP = x.SP,
MCC = x.MCC,
MLSTN = t
})
.Join(groups,
x => x.MA.MAId,
g => g.MAId,
(x, g) => new
{
MA = x.MA ,
A = x.A,
SP = x.SP,
MCC = x.MCC,
MLSTN = t,
MLSG = g
});