Remove duplicate column values of a datatable

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I have a datatable like below:

Name               Department
John Alter         D01
Prakash Kiran      D01
Steffy Cold        D01
Julia Roberts      D02
Candy Mitchel      D02
Monika Diesel      D03


I want it like below: 

Name               Department
John Alter         D01
Prakash Kiran      
Steffy Cold        
Julia Roberts      D02
Candy Mitchel      
Monika Diesel      D03


when its ordered by a department, it should not repeat for the same department.
But the row should be there, only if there is same value in next row under Department column, that needs to be BLANK

help ASAP

What I have tried:

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Used the below code from someone.. but its not working

C#

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DataTable newDt = dt.Clone();
for (int i = 0; i < dt.Rows.Count; i++)
{
    DataRow newRow = newDt.NewRow();
    newRow["Name"] = dt.Rows[i]["Name"];
    int originalIndex = dt.AsEnumerable().ToList().FindIndex(x => x["Department"] == dt.Rows[i]["Department"]);
    if (originalIndex < i)
    {
        newRow["Department"] = "";
    }
    else
    {
        newRow["Department"] = dt.Rows[i]["Department"];
    }
    newDt.Rows.Add(newRow);
}

Posted 1-Aug-17 23:18pm

Kingshuk_SP

Updated 1-Aug-17 23:29pm

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2 solutions

Solution 1

try

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DataTable dt = new DataTable();
           dt.Columns.Add("Name");
           dt.Columns.Add("Department");
           dt.Rows.Add("John Alter", "D01");
           dt.Rows.Add("Prakash Kiran", "D01");
           dt.Rows.Add("Steffy Cold", "D01");
           dt.Rows.Add("Julia Roberts", "D02");
           dt.Rows.Add("Candy Mitchel", "D02");
           dt.Rows.Add("Monika Diesel", "D03");
           var departments = dt.AsEnumerable().Select(k => k.Field<string>("Department")).Distinct().OrderBy(k=>k).ToArray();

           foreach (string dept in departments)
           {
               int i = 0;
               foreach (DataRow row in dt.Rows)
               {
                   if (row["Department"].ToString() == dept) {
                       if (i > 0) {
                           row["Department"] = "";
                       }
                       i++;
                   }
               }
           }

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Posted 1-Aug-17 23:28pm

Karthik_Mahalingam

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This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Thomas Daniels · Accepted Answer · 2017-08-01T23:29:00

That code was mine and as we established in our comment discussion, replacing the == operator by the .Equals method works.

For future reference, here's why that worked:
The return type of x["Department"] and dt.Rows[i]["Department"] is object (and not string, because the table can contain other data as well). When == is used on object, this is the equivalent of calling Object.ReferenceEquals[^] - here it doesn't matter that the actual type is a string, Object.ReferenceEquals is still used (and that's what I forgot when writing the original code). If you use .Equals however, then it will use String.Equals[^] (which is what you want), because you have a string and the String type overrides Object.Equals.

Remove duplicate column values of a datatable

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Remove duplicate column values of a datatable

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