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C#  Merge 2 dataset based on primary key or 1 column

Posted on 2013-06-11
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Last Modified: 2013-06-12
Hi..
I have 2 datasets I need to merge them for only the rows that match on a single column between them.

Table 1                                  Table 2

ID         Name                         ID     Name
1            John                           1       Bob
2            Jane                           3        Fred


Want to merge table 1 with table 2   - only  Bob should be added to table 1

What's the best way to do this a loop or can I do via LINQ

thx
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Question by:JElster
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5 Comments
 
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Expert Comment

by:käµfm³d 👽
ID: 39239821
Where does this data live? Is it literally in a DataSet, or is it in the database and you are retrieving it via LINQ (or another method)?
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Author Comment

by:JElster
ID: 39239825
It's now in a DataSet...  complex queries add to dataset to be export to CSV
Can't mod queries
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Expert Comment

by:käµfm³d 👽
ID: 39239831
So what would Bob's ID be once he was merged into Table 1?
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Author Comment

by:JElster
ID: 39239836
Doesn't matter ID isn't exported

Maybe something like this...
 DataSet dsTEMP = dsUsers.Clone();

                foreach (DataRow dr in dsUsers.Tables[0].Rows)
                {
                    DataRow[] results = dsOther.Tables[0].Select("ID = '" +dr["ID"].ToString()+"'");

                    if (results.Count() > 0)
                    {
               
                        foreach (DataRow _d in results)
                        {

                            dsTEMP.Tables[0].ImportRow(_d);
                        }
                    }

                }
               
                dsUsers.Merge(dsTEMP);
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Accepted Solution

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käµfm³d   👽 earned 500 total points
ID: 39239915
See if this approach works for you. I'm including how I populated the tables.

static void Main(string[] args)
{
    DataSet table1 = new DataSet();
    DataSet table2 = new DataSet();
    DataSet dsTEMP = new DataSet();

    table1.Tables.Add(new DataTable());
    table1.Tables[0].Columns.Add("ID", typeof(int));
    table1.Tables[0].Columns.Add("Name", typeof(string));
    table1.Tables[0].Rows.Add(1, "John");
    table1.Tables[0].Rows.Add(2, "Jane");

    table2.Tables.Add(new DataTable());
    table2.Tables[0].Columns.Add("ID", typeof(int));
    table2.Tables[0].Columns.Add("Name", typeof(string));
    table1.Tables[0].Rows.Add(1, "Bob");
    table1.Tables[0].Rows.Add(3, "Fred");

    var query = from row1 in table1.Tables[0].AsEnumerable()
                join row2 in table2.Tables[0].AsEnumerable()
                on row1.Field<int>("ID") equals row2.Field<int>("ID")
                select row2;

    dsTEMP.Tables.Add(table1.Tables[0].AsEnumerable()
                                      .Concat(query)
                                      .CopyToDataTable());
}

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