distinct not working in linq

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Hi
i want to get the distinct EmployeeId for the following query. I used Distinct but its not working

var emp= (from dr in dt.AsEnumerable() orderby dr["EmployeeID"] descending
         select new Employee(){
EmployeeId = int.Parse(dr"EmployeeID"].ToString()),     
EmployeeName = dr["EmployeeName"].ToString(),
EmployeeDesignation = dr["EmployeeDesignation"].ToString()
         }).Distinct();

Posted 24-Oct-12 21:14pm

Nivas Maran

Updated 24-Oct-12 21:23pm

v2

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OriginalGriff · Answer 1 · 2012-10-24T21:53:00

Since you have added the "." and it's still not working, I am guessing that your class does not implement IEquatable.
What that means is that Distinct will use the default comparer, which for a class is a Reference comparison. Since all your instances are new instances, they will all fail a reference comparison, because the references are not the same.

You need to either implement IEquatable<Employee> and provide the Equals method (at a guess comparing EmployeeID values) and the GetHashCode method, or provide a custom comparer to the Distinct call: http://msdn.microsoft.com/en-us/library/bb338049.aspx[^] describes it and provides an example.

OriginalGriff · Answer 2 · 2012-10-24T21:20:00

You need a '.' before the word "Distinct":

C#

var emp= (from dr in dt.AsEnumerable() orderby dr["EmployeeID"] descending
         select new Employee(){
EmployeeId = int.Parse(dr"EmployeeID"].ToString()),
EmployeeName = dr["EmployeeName"].ToString(),
EmployeeDesignation = dr["EmployeeDesignation"].ToString()
         })Distinct();

Becomes:

C#

var emp= (from dr in dt.AsEnumerable() orderby dr["EmployeeID"] descending
         select new Employee(){
EmployeeId = int.Parse(dr"EmployeeID"].ToString()),
EmployeeName = dr["EmployeeName"].ToString(),
EmployeeDesignation = dr["EmployeeDesignation"].ToString()
         }).Distinct();

Sushil Mate · Answer 3 · 2012-10-24T21:21:00

Why it will work.

C#

var emp= (from dr in dt.AsEnumerable() orderby dr["EmployeeID"] descending
         select new Employee(){
EmployeeId = int.Parse(dr"EmployeeID"].ToString()),     
EmployeeName = dr["EmployeeName"].ToString(),
EmployeeDesignation = dr["EmployeeDesignation"].ToString()
         }).Distinct();

Unareshraju · Answer 4 · 2012-10-24T22:44:00

Solution 6

hi
i hope here is suitable answer to you.
http://stackoverflow.com/questions/4318909/linq-to-sql-distinct-and-orderby[^]

Posted 24-Oct-12 22:44pm

Unareshraju

Sarvesh Kushwaha · Answer 5 · 2012-10-24T21:24:00

C#

var emp= (from dr in dt.AsEnumerable() orderby dr["EmployeeID"] descending
         select new Employee(){
EmployeeId = int.Parse(dr"EmployeeID"].ToString()),
EmployeeName = dr["EmployeeName"].ToString(),
EmployeeDesignation = dr["EmployeeDesignation"].ToString()
         })Distinct();

Solution 1.

i think you missed . operater in your query , make it .Distinct()

or

SOlution 2.

another way is use a stored procedure and then add that SP to your DBML. It will create a simple function that you can then call through LINQ.

manak chand · Answer 6 · 2012-10-24T22:18:00

Solution 5

Try this

EmployeeId = int.Parse(dr["EmployeeID]"])

or

EmployeeId = int.Parse(dr["EmployeeID"].ToString())

instead of

EmployeeId = int.Parse(dr"EmployeeID"].ToString())

Posted 24-Oct-12 22:18pm

manak chand

Updated 24-Oct-12 22:19pm

v2

distinct not working in linq

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