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Join 2 DataTables into 1 in C# [duplicate]

This question already has answers here:
how to join two datatable datas into one datatable to show in one gridview in asp.net
(4 answers)
Closed 9 years ago.
I have two identical DataTables from two different databases (but the ids are unique!). So now I want to have combine this data into a single DataTable. I have no idea what to do.
I tried the following:
DataTable one = new DataTable();
one = baza_win.pobierz_dane("SELECT...");
DataTable two = new DataTable();
two = baza_win2.pobierz_dane("SELECT...");
//DataTable sum = one + two;
DataTable sum = new DataTable();
sum.Clone(one);
sum.Merge(two,false);
But this doesn't work at sum.Clone(one);
Any ideas?

sum = one.Copy();
sum.Merge(two);

I think you need Copy instead of Clone:
DataTable one = new DataTable();
one = baza_win.pobierz_dane("SELECT...");
DataTable two = new DataTable();
two = baza_win2.pobierz_dane("SELECT...");
//DataTable sum = one + two;
DataTable sum = new DataTable();
sum.Copy(one);
sum.Merge(two,false);

copied from link
http://msdn.microsoft.com/en-us/library/fk68ew7b.aspx
duplicate of
how to join two datatable datas into one datatable to show in one gridview in asp.net
private static void DemonstrateMergeTable()
{
DataTable table1 = new DataTable("Items");
// Add columns
DataColumn column1 = new DataColumn("id", typeof(System.Int32));
DataColumn column2 = new DataColumn("item", typeof(System.Int32));
table1.Columns.Add(column1);
table1.Columns.Add(column2);
// Set the primary key column.
table1.PrimaryKey = new DataColumn[] { column1 };
// Add RowChanged event handler for the table.
table1.RowChanged +=
new System.Data.DataRowChangeEventHandler(Row_Changed);
// Add some rows.
DataRow row;
for (int i = 0; i <= 3; i++)
{
row = table1.NewRow();
row["id"] = i;
row["item"] = i;
table1.Rows.Add(row);
}
// Accept changes.
table1.AcceptChanges();
PrintValues(table1, "Original values");
// Create a second DataTable identical to the first.
DataTable table2 = table1.Clone();
// Add three rows. Note that the id column can't be the
// same as existing rows in the original table.
row = table2.NewRow();
row["id"] = 14;
row["item"] = 774;
table2.Rows.Add(row);
row = table2.NewRow();
row["id"] = 12;
row["item"] = 555;
table2.Rows.Add(row);
row = table2.NewRow();
row["id"] = 13;
row["item"] = 665;
table2.Rows.Add(row);
// Merge table2 into the table1.
Console.WriteLine("Merging");
table1.Merge(table2);
PrintValues(table1, "Merged With table1");
}
private static void Row_Changed(object sender,
DataRowChangeEventArgs e)
{
Console.WriteLine("Row changed {0}\t{1}",
e.Action, e.Row.ItemArray[0]);
}
private static void PrintValues(DataTable table, string label)
{
// Display the values in the supplied DataTable:
Console.WriteLine(label);
foreach (DataRow row in table.Rows)
{
foreach (DataColumn col in table.Columns)
{
Console.Write("\t " + row[col].ToString());
}
Console.WriteLine();
}
}

try the following... CLONE the first table so it has proper structure, THEN merge two into it.
DataTable sum = one.Clone()
sum.Merge(two,false);

two datatable adding

I have two datatables.
1st table-----> DataTable _dtMain = new COrder().GetDetails();
2nd table-----> DataTable _dtSub = new CGrid().GetSubDetails();
I want to add the above two tables. I am using _dtMain.Merge(_dtSub );
But it will append _dtSub table to _dtMain table. I want datatable to add second table to first table in column wise (that means after first table last column)

Don't think there any built-in method for the thing you want to achieve.
I think you need to make your own implementation for that stuff, like for example an extension method
public static DataTable Aggregate(this DataTable dt1, DataTable dt2)
{
var aggregator = new DataTable();
//add columns from dt1 and dt2
//add rows from dt1 dt2
}
or, you can do a complete Outer Join on both tables, like descrived in this article.

After a lot of research , i find out the answer for my question that i posted before. Here is the code for combing 2 datatable & the data inside it.
public DataTable CombineTable(DataTable _dtGridDetails, DataTable _dtSubGridDetails)
{
//first create the datatable columns
DataSet mydataSet = new DataSet();
mydataSet.Tables.Add(" ");
DataTable myDataTable = mydataSet.Tables[0];
//add left table columns
DataColumn[] dcLeftTableColumns = new DataColumn[_dtGridDetails.Columns.Count];
_dtGridDetails.Columns.CopyTo(dcLeftTableColumns, 0);
foreach (DataColumn LeftTableColumn in dcLeftTableColumns)
{
if (!myDataTable.Columns.Contains(LeftTableColumn.ToString()))
myDataTable.Columns.Add(LeftTableColumn.ToString());
}
//now add right table columns
DataColumn[] dcRightTableColumns = new DataColumn[_dtSubGridDetails.Columns.Count];
_dtSubGridDetails.Columns.CopyTo(dcRightTableColumns, 0);
foreach (DataColumn RightTableColumn in dcRightTableColumns)
{
if (!myDataTable.Columns.Contains(RightTableColumn.ToString()))
{
// if (RightTableColumn.ToString() != RightPrimaryColumn)
myDataTable.Columns.Add(RightTableColumn.ToString());
}
}
//add left-table data to mytable
foreach (DataRow LeftTableDataRows in _dtGridDetails.Rows)
{
myDataTable.ImportRow(LeftTableDataRows);
}
for (int nIndex = 0; nIndex <= myDataTable.Rows.Count-1; nIndex++)
{
if (nIndex == _dtSubGridDetails.Rows.Count)
break;
myDataTable.Rows[nIndex][columnindex] = _dtSubGridDetails.Rows[nIndex][columnindex];
}
return myDataTable;
}

Sorting rows in a data table

We have two columns in a DataTable, like so:
COL1 COL2
Abc 5
Def 8
Ghi 3
We're trying to sort this datatable based on COL2 in decreasing order.
COL1 COL2
ghi 8
abc 4
def 3
jkl 1
We tried this:
ft.DefaultView.Sort = "COL2 desc";
ft = ft.DefaultView.ToTable(true);
but, without using a DataView, we want to sort the DataTable itself, not the DataView.

I'm afraid you can't easily do an in-place sort of a DataTable like it sounds like you want to do.
What you can do is create a new DataTable from a DataView that you create from your original DataTable. Apply whatever sorts and/or filters you want on the DataView and then create a new DataTable from the DataView using the DataView.ToTable method:
DataView dv = ft.DefaultView;
dv.Sort = "occr desc";
DataTable sortedDT = dv.ToTable();

This will help you...
DataTable dt = new DataTable();
dt.DefaultView.Sort = "Column_name desc";
dt = dt.DefaultView.ToTable();

Its Simple Use .Select function.
DataRow[] foundRows=table.Select("Date = '1/31/1979' or OrderID = 2", "CompanyName ASC");
DataTable dt = foundRows.CopyToDataTable();
And it's done......Happy Coding

Maybe the following can help:
DataRow[] dataRows = table.Select().OrderBy(u => u["EmailId"]).ToArray();
Here, you can use other Lambda expression queries too.

Or, if you can use a DataGridView, you could just call Sort(column, direction):
namespace Sorter
{
using System;
using System.ComponentModel;
using System.Windows.Forms;
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
this.dataGridView1.Rows.Add("Abc", 5);
this.dataGridView1.Rows.Add("Def", 8);
this.dataGridView1.Rows.Add("Ghi", 3);
this.dataGridView1.Sort(this.dataGridView1.Columns[1],
ListSortDirection.Ascending);
}
}
}
Which would give you the desired result:

Did you try using the Select(filterExpression, sortOrder) method on DataTable? See here for an example. Note this method will not sort the data table in place, if that is what you are looking for, but it will return a sorted array of rows without using a data view.

table.DefaultView.Sort = "[occr] DESC";

Use LINQ - The beauty of C#
DataTable newDataTable = baseTable.AsEnumerable()
.OrderBy(r=> r.Field<int>("ColumnName"))
.CopyToDataTable();

There is 2 way for sort data
1) sorting just data and fill into grid:
DataGridView datagridview1 = new DataGridView(); // for show data
DataTable dt1 = new DataTable(); // have data
DataTable dt2 = new DataTable(); // temp data table
DataRow[] dra = dt1.Select("", "ID DESC");
if (dra.Length > 0)
dt2 = dra.CopyToDataTable();
datagridview1.DataSource = dt2;
2) sort default view that is like of sort with grid column header:
DataGridView datagridview1 = new DataGridView(); // for show data
DataTable dt1 = new DataTable(); // have data
dt1.DefaultView.Sort = "ID DESC";
datagridview1.DataSource = dt1;

It turns out there is a special case where this can be achieved. The trick is when building the DataTable, collect all the rows in a list, sort them, then add them. This case just came up here.

//Hope This will help you..
DataTable table = new DataTable();
//DataRow[] rowArray = dataTable.Select();
table = dataTable.Clone();
for (int i = dataTable.Rows.Count - 1; i >= 0; i--)
{
table.ImportRow(dataTable.Rows[i]);
}
return table;

TL;DR
use tableObject.Select(queryExpression, sortOrderExpression) to select data in sorted manner
Complete example
Complete working example - can be tested in a console application:
using System;
using System.Data;
namespace A
{
class Program
{
static void Main(string[] args)
{
DataTable table = new DataTable("Orders");
table.Columns.Add("OrderID", typeof(Int32));
table.Columns.Add("OrderQuantity", typeof(Int32));
table.Columns.Add("CompanyName", typeof(string));
table.Columns.Add("Date", typeof(DateTime));
DataRow newRow = table.NewRow();
newRow["OrderID"] = 1;
newRow["OrderQuantity"] = 3;
newRow["CompanyName"] = "NewCompanyName";
newRow["Date"] = "1979, 1, 31";
// Add the row to the rows collection.
table.Rows.Add(newRow);
DataRow newRow2 = table.NewRow();
newRow2["OrderID"] = 2;
newRow2["OrderQuantity"] = 2;
newRow2["CompanyName"] = "NewCompanyName1";
table.Rows.Add(newRow2);
DataRow newRow3 = table.NewRow();
newRow3["OrderID"] = 3;
newRow3["OrderQuantity"] = 2;
newRow3["CompanyName"] = "NewCompanyName2";
table.Rows.Add(newRow3);
DataRow[] foundRows;
Console.WriteLine("Original table's CompanyNames");
Console.WriteLine("************************************");
foundRows = table.Select();
// Print column 0 of each returned row.
for (int i = 0; i < foundRows.Length; i++)
Console.WriteLine(foundRows[i][2]);
// Presuming the DataTable has a column named Date.
string expression = "Date = '1/31/1979' or OrderID = 2";
// string expression = "OrderQuantity = 2 and OrderID = 2";
// Sort descending by column named CompanyName.
string sortOrder = "CompanyName ASC";
Console.WriteLine("\nCompanyNames data for Date = '1/31/1979' or OrderID = 2, sorted CompanyName ASC");
Console.WriteLine("************************************");
// Use the Select method to find all rows matching the filter.
foundRows = table.Select(expression, sortOrder);
// Print column 0 of each returned row.
for (int i = 0; i < foundRows.Length; i++)
Console.WriteLine(foundRows[i][2]);
Console.ReadKey();
}
}
}
Output

try this:
DataTable DT = new DataTable();
DataTable sortedDT = DT;
sortedDT.Clear();
foreach (DataRow row in DT.Select("", "DiffTotal desc"))
{
sortedDT.NewRow();
sortedDT.Rows.Add(row);
}
DT = sortedDT;

Yes the above answers describing the corect way to sort datatable
DataView dv = ft.DefaultView;
dv.Sort = "occr desc";
DataTable sortedDT = dv.ToTable();
But in addition to this, to select particular row in it you can use LINQ and try following
var Temp = MyDataSet.Tables[0].AsEnumerable().Take(1).CopyToDataTable();

how to reset rows to newly added column with its default value

I have created an application that shows data in data table. it also provide user interface for adding new column to a data table with its default value.
But problem is, It showing newly created column in data table but default value is not coming. I have to populate data table again to do this which reduces my app performance.
So, how do i overcome this problem...
EDIT:
obj_dataTable.Columns.Add(columnName);
int index = obj_dataTable.Columns.IndexOf(obj_dataTable.Columns[columnName]);
obj_dataTable.Columns[index].DefaultValue = defaultValue;

Default values are assigned when you add a row to the table and the column is not already assigned a value. Therefore, existing rows will not be updated when you change the schema. If you want a generic means of updating a table and applying the default to existing rows then Id create a method to copy the rows from the current data table to a new data table with the extra column in it. Eg:
void doTableStuff()
{
DataTable table1 = makeTable();
table1.Rows.Add(new string[] { "Frederic", "Robert" });
table1 = updateTable(table1);
if (table1.Rows[0]["Sam"] == "Samantha")
{
Console.WriteLine("I Was Right!");
}
else
{
Console.WriteLine("I Was Wrong!");
}
}
DataTable makeTable()
{
DataTable dt = new DataTable();
dt.Columns.Add(new DataColumn { ColumnName = "Fred", DataType = typeof(string), DefaultValue = "fred" });
dt.Columns.Add(new DataColumn { ColumnName = "Bob", DataType = typeof(string), DefaultValue = "bob" });
return dt;
}
DataTable updateTable(DataTable oldTable)
{
DataTable newTable = makeTable();
newTable.Columns.Add(new DataColumn { ColumnName = "Sam", DataType = typeof(string), DefaultValue = "Samantha" });
newTable.Merge(oldTable, true, MissingSchemaAction.Add);
return newTable;
}
Sorry, I didn't try running this but you should get the idea. Hope that works.
Cheers

How to 'union' 2 or more DataTables in C#?

How to 'union' 2 or more DataTables in C#?
Both table has same structure.
Is there any build-in function or should we do manually?

You are looking most likely for the DataTable.Merge method.
Example:
private static void DemonstrateMergeTable()
{
DataTable table1 = new DataTable("Items");
// Add columns
DataColumn idColumn = new DataColumn("id", typeof(System.Int32));
DataColumn itemColumn = new DataColumn("item", typeof(System.Int32));
table1.Columns.Add(idColumn);
table1.Columns.Add(itemColumn);
// Set the primary key column.
table1.PrimaryKey = new DataColumn[] { idColumn };
// Add RowChanged event handler for the table.
table1.RowChanged += new
System.Data.DataRowChangeEventHandler(Row_Changed);
// Add ten rows.
DataRow row;
for (int i = 0; i <= 9; i++)
{
row = table1.NewRow();
row["id"] = i;
row["item"] = i;
table1.Rows.Add(row);
}
// Accept changes.
table1.AcceptChanges();
PrintValues(table1, "Original values");
// Create a second DataTable identical to the first.
DataTable table2 = table1.Clone();
// Add column to the second column, so that the
// schemas no longer match.
table2.Columns.Add("newColumn", typeof(System.String));
// Add three rows. Note that the id column can't be the
// same as existing rows in the original table.
row = table2.NewRow();
row["id"] = 14;
row["item"] = 774;
row["newColumn"] = "new column 1";
table2.Rows.Add(row);
row = table2.NewRow();
row["id"] = 12;
row["item"] = 555;
row["newColumn"] = "new column 2";
table2.Rows.Add(row);
row = table2.NewRow();
row["id"] = 13;
row["item"] = 665;
row["newColumn"] = "new column 3";
table2.Rows.Add(row);
// Merge table2 into the table1.
Console.WriteLine("Merging");
table1.Merge(table2, false, MissingSchemaAction.Add);
PrintValues(table1, "Merged With table1, schema added");
}
private static void Row_Changed(object sender,
DataRowChangeEventArgs e)
{
Console.WriteLine("Row changed {0}\t{1}", e.Action,
e.Row.ItemArray[0]);
}
private static void PrintValues(DataTable table, string label)
{
// Display the values in the supplied DataTable:
Console.WriteLine(label);
foreach (DataRow row in table.Rows)
{
foreach (DataColumn col in table.Columns)
{
Console.Write("\t " + row[col].ToString());
}
Console.WriteLine();
}
}

You could try this:
public static DataTable Union (DataTable First, DataTable Second)
{
//Result table
DataTable table = new DataTable("Union");
//Build new columns
DataColumn[] newcolumns = new DataColumn[First.Columns.Count];
for(int i=0; i < First.Columns.Count; i++)
{
newcolumns[i] = new DataColumn(
First.Columns[i].ColumnName, First.Columns[i].DataType);
}
table.Columns.AddRange(newcolumns);
table.BeginLoadData();
foreach(DataRow row in First.Rows)
{
table.LoadDataRow(row.ItemArray,true);
}
foreach(DataRow row in Second.Rows)
{
table.LoadDataRow(row.ItemArray,true);
}
table.EndLoadData();
return table;
}
From here (not tested).

You could use Concat from Linq to datasets (get the free chapter of LINQ in Action) to join them and then .AsDataTable to create the table (assuming you actually want them as a DataTable)

Stumbled across this question, and Ruben Bartelink gave a great answer, but with no code. So I had to look it up elsewhere, which defeats the point of StackOverflow. Now that it's 2010, the other answers given aren't quite as viable. For reference, here's code demonstrating the CopyToDataTable() extension method. It's in VB so as to not steal the credit from Ruben if he wants to revisit the past and post a more complete answer :)
Public Function GetSchema(ByVal dbNames As IEnumerable(Of String)) As DataTable
Dim schemaTables As New List(Of DataTable)()
For Each dbName As String In dbNames
Dim cnnStr = GetConnectionString(dbName)
Dim cnn As New SqlConnection(cnnStr)
cnn.Open()
Dim dt = cnn.GetSchema("Columns")
cnn.Close()
schemaTables.Add(dt)
Next
Dim dtResult As DataTable = Nothing
For Each dt As DataTable In schemaTables
If dtResult Is Nothing Then
dtResult = dt
Else
dt.AsEnumerable().CopyToDataTable(dtResult, LoadOption.PreserveChanges)
End If
Next
Return dtResult
End Function

Try this using Linq to DataSet, must add the reference for System.Data.DataSetExtensions.dll, another approach, alternative for DataTable.Merge method).
static void Main(string[] args)
{
DoUnion();
}
private static void DoUnion()
{
DataTable table1 = GetProducts();
DataTable table2 = NewProducts();
var tbUnion = table1.AsEnumerable()
.Union(table2.AsEnumerable());
DataTable unionTable = table1.Clone();
foreach (DataRow fruit in tbUnion)
{
var fruitValue = fruit.Field<string>(0);
Console.WriteLine("{0}->{1}", fruit.Table, fruitValue);
DataRow row = unionTable.NewRow();
row.SetField<string>(0, fruitValue);
unionTable.Rows.Add(row);
}
}
private static DataTable NewProducts()
{
DataTable table = new DataTable("CitricusTable");
DataColumn col = new DataColumn("product", typeof(string));
table.Columns.Add(col);
string[] citricusFruits = { "Orange", "Grapefruit", "Lemon", "Lime", "Tangerine" };
foreach (string fruit in citricusFruits)
{
DataRow row = table.NewRow();
row.SetField<string>(col, fruit);
table.Rows.Add(row);
}
return table;
}
private static DataTable GetProducts()
{
DataTable table = new DataTable("MultipleFruitsTable");
DataColumn col = new DataColumn("product", typeof(string));
table.Columns.Add(col);
string[] multipleFruits = { "Breadfruit", "Custardfruit", "Jackfruit", "Osage-orange", "Pineapple" };
foreach (string fruit in multipleFruits)
{
DataRow row = table.NewRow();
row.SetField<string>(col, fruit);
table.Rows.Add(row);
}
return table;
}
antonio