Select multiple tables in LINQ

Posted on 2014-09-04
Last Modified: 2016-02-15
Hi Experts,

I have this SQL query statement:

FROM FinanceDept d1
(SELECT User_ID, MAX(SalesAmt) AS 'Amount' FROM SalesDept GROUP BY User_ID) d2
ON d1.User_ID = d2.User_ID AND d1.Amount= d2.Amount

But I don't know how to write it in LINQ and Lambda expression.
Please help.

Thank you
Question by:alexcryout
  • 2
  • 2
LVL 69

Accepted Solution

Éric Moreau earned 250 total points
ID: 40305509
LVL 62

Assisted Solution

by:Fernando Soto
Fernando Soto earned 250 total points
ID: 40305938
Hi alexcryout;

Try this query and see if it returns the required results.

var results = from d1 in FinanceDept
              join d2 in SalesDept on new { d1.User_ID, d1.Amount  } equals new { d.OrderID, d2.Amount } into userGroup
              orderby d1.User_ID
              select new 
                 FinanceDept = d1,
                 User_ID_d2 = userGroup.Select( u => u.User_ID ).FirstOrDefault(),
                 Amount = userGroup.Max( a = a.SalesAmt )

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Author Comment

ID: 40306230
Hi Fernando,

Sorry for my typo, I am trying to join the same table. The correct SQL statement is:

 FROM FinanceDept d1
 (SELECT User_ID, MAX(SalesAmt) AS 'Amount' FROM FinanceDept GROUP BY User_ID) d2
 ON d1.User_ID = d2.User_ID AND d1.Amount= d2.Amount

LVL 62

Expert Comment

by:Fernando Soto
ID: 40306311
Hi alexcryout;

Just substitute the table name SalesDept with FinanceDept as shown in this line of the query and that should do it.

(SELECT User_ID, MAX(SalesAmt) AS 'Amount' FROM FinanceDept GROUP BY User_ID) d2

Author Closing Comment

ID: 40306382
It works fine but I download the Linqer tool and its solution is much better.

Thank you for all your helps.

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