CODEWITHSUNDEEP
c#linqc#-4.0datatable
user3102858
user3102858

Reputation: 128

How to join two tables using c# 4.0?

I have the same issue as here is LINQ join two DataTables but my datatables are made on runtime like

DataTable dtTML = (DataTable)JsonConvert.DeserializeObject(Convert.ToString(data.Json.Args[0]["TML"]), (typeof(DataTable)));

the solution that someone gave is fine but I am getting error on datarows2 at

select dtResult.LoadDataRow(new object[]
{
  dataRows2.Field<int>("stock") // here is error : does not exist in current context
}

while dataRows1.Field(s) are fine

Upvotes: 0

Views: 187

Answers (1)

Zein Makki
Zein Makki

Reputation: 30022

I can't see what's wrong with this approach :

DataTable dt1 = new DataTable();
dt1.Columns.Add("PK", typeof(int));
dt1.Columns.Add("Data1", typeof(int));

DataTable dt2 = new DataTable();
dt2.Columns.Add("FK", typeof(int));
dt2.Columns.Add("Data2", typeof(int));

dt2.Rows.Add(1, 5000);
dt1.Rows.Add(1, 1000);

var Result = (from r1 in dt1.AsEnumerable()
              join r2 in dt2.AsEnumerable()
              on r1["PK"] equals r2["FK"]
              select new
              {
                  A = r1.Field<int>("Data1"),
                  B = r2.Field<int>("Data2"),
                  //  choose more columns if any
              }).ToList();

You can do whatever you want using it. If you need the result to be a Datatable , just use this method [ ListToDataTable ] to convert List to DataTable:

public static DataTable ListToDataTable<T>(List<T> items)
{

    System.ComponentModel.PropertyDescriptorCollection properties =
    System.ComponentModel.TypeDescriptor.GetProperties(typeof(T));
    DataTable table = new DataTable();
    foreach (System.ComponentModel.PropertyDescriptor prop in properties)
        table.Columns.Add(prop.Name, Nullable.GetUnderlyingType(prop.PropertyType) ?? prop.PropertyType);
    foreach (T item in items)
    {
        DataRow row = table.NewRow();
        foreach (System.ComponentModel.PropertyDescriptor prop in properties)
            row[prop.Name] = prop.GetValue(item) ?? DBNull.Value;
        table.Rows.Add(row);
    }
    return table;

Upvotes: 1

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