I'm trying to add to a new DataSet X a DataTable that is inside of a different DataSet Y.
If I add it directly, I get the following error:
DataTable already belongs to another DataSet.
Do I have to clone the DataTable and import all the rows to it and then add the new DataTable to the new DataSet? Is there a better/easy way to do it?
There are two easy ways to do this:
DataTable.Copy
Instead of DataTable.Clone, use DataTable.Copy to create a copy of your data table; then insert the copy into the target DataSet:
dataSetX.Tables.Add( dataTableFromDataSetY.Copy() );
DataSet.Merge
You could also use DataSet.Merge for this:
dataSetX.Merge(dataTableFromDataSetY);
Note, however, that if you are going to use this method, you might want to make sure that your target DataSet doesn't already contain a table with the same name:
If the target DataSet doesn't contain a table by the same name, a fresh copy of the table is created inside the data set;
If a table by the same name is already in the target data set, then it will get merged with the one passed to Merge, and you end up with a mix of the two.
Use this generic function
public DataTable CopyDataTable(DataTable dtSource, int iRowsNeeded)
{
if (dtSource.Rows.Count > iRowsNeeded)
{
// cloned to get the structure of source
DataTable dtDestination = dtSource.Clone();
for (int i = 0; i < iRowsNeeded; i++)
{
dtDestination.ImportRow(dtSource.Rows[i]);
}
return dtDestination;
}
else
return dtSource;
}
Suppose you want to copy first table of sourceSet to destinationSet.
Call it like
DataTable destinationTable = CopyDataTable(sourceSet.Tables[0], sourceSet.Tables[0].Rows.Count);
DataSet destinationSet = new DataSet();
destinationSet.Tables.Add(destinationTable);
This should work for you
X.Tables.Add(Y.Tables[<tablename|index>].Copy());
IEnumerable<DataRow> query = from sourceTbl in sourceTbl.AsEnumerable()
where [any condition you want]
select order;
DataTable boundTable = query.CopyToDataTable<DataRow>();
I am not sure If i understood your question properly.Hope this code helps
Related
I have created a datatable which has some records, now what I want is to copy the record of first datatable to another datatable.
I tried like below:
Session["AmountData"] = AmountDatatable; // 1st datatable which has data
DataTable CompanyWiseRecord = new DataTable();
for (int i = 0; i < AmountDatatable.Rows.Count; i++)
{
CompanyWiseRecord.ImportRow(AmountDatatable.Rows[i]); // 2nd datatable which does not have data
}
Kindly let me know where I am going wrong.
You directly use session Like:
DataTable CompanyWiseRecord = (DataTable)Session["AmountData"]; //Retrieving DataTable from Session.
if you are not fetching data from table one based on some condition or assign particular rows or columns then You can do it simply by using
DataTable CompanyWiseRecord=AmountDatatable;
Is it possible to add a row to the middle of an existing dataset with c#? I've done a lot of searching and haven't been able to find anything on how to do this. What have I tried? I've tried searching a lot and haven't found anything like an 'insertAt' method for datasets.
Thanks
Mike
The DataSet consists of a collection of DataTable objects so I assume that you are talking about a Datatable, right? If so, it has an InsertAt method:
DataTable dt = dataset.Tables[0]; //Get first datatable from dataset
DataRow row = dt.NewRow();
//fill row
dt.Rows.InsertAt(row,3); //Insert at index 3
DataSet does not have a rows collection, so you can't add a row to it at all.
You can insert a row by index into a DataTable object using DataTable.Rows.InsertAt(row, i). If the table is in a DataSet, your syntax would be DataSet.Tables[i].Rows.InsertAt(row, 0)
In my opinion (though this could take a lot of time), you can create an array or a list array then transfer all the data there from your dataset through for loop or any loop...then put an if statement inside to check where you want to put your extra data like this:
List<string> arrayList = dataset;// i know this is not possible just showing you that you have to put all your data from dataset to array:)
List <string> newList = new List<string>();//its up to you if you want to put another temporary array or you could simply output your data from the loop.
//THE LOOP
for(int i = 0; i<=arrayList.Count(); i++){
if(i == x)//x is the index or you may change this statement its up to you
{
//do the print or pass the data to newList
newList.add(arraList[i]);//not sure about this. its been a while since the last time i use this array list..
}
}
another way is customize your query(if your pulling out some data from database)
happy coding:)
Here's a short sample of doing it:
class Program
{
static void Main(string[] args)
{
DataSet ds = new DataSet();
DataTable dt = ds.Tables.Add("Table");
dt.Columns.Add("Id");
for (int i = 0; i < 10; i++)
{
dt.Rows.Add(new object[]{i});
}
var newRow=dt.NewRow();
newRow.ItemArray=new string[]{(dt.Rows.Count/2).ToString()+".middle"};
dt.Rows.InsertAt(newRow, dt.Rows.Count / 2);
}
}
How can I copy 1 data column from 1 data table to a new datatable. When I try to do it, I get the error Column 'XXX' already belongs to another DataTable.?
dataColumn = datatable1.Columns[1];
datatable2 = new DataTable();
datatable2.Columns.Add(dataColumn);
Thanks in Advance
You cannot copy DataColumns. What you'll need to do is create a new DataColumn in the new datatable with the same data type as in the old datatable's column, and then you need to run a FOR loop to bring in all the data from the old datatable to the new datatable.
See the following code. This assumes that the datatables have exactly the same number of rows.
DataTable dt1 = new DataTable();
DataTable dt2 = new DataTable();
dt2.Columns.Add("ColumnA", dt1.Columns["ColumnA"].DataType);
for (int i = 0; i < dt1.Rows.Count; i++)
{
dt2.Rows[i]["ColumnA"] = dt1.Rows[i]["ColumnA"];
}
Also, If the data you are copying are reference types and not value types you might want to see if a .Clone() method is available for the type, or make one yourself. Just doing 'this = that' in the FOR loop will not work on reference types.
You cannot copy a DataColumn. (DataColumns are very tightly coupled with their tables)
Instead, you can add a new column with the same name and datatype.
You might be looking for DataTable.Clone(), which will create a structual copy of an entire table. (With the same schema, but no data)
Just a thought, are your DataTables both in the same DataSet?
If so, you can create a named DataRelation between the columns of two tables (think foreign key).
Then you can add a Calculated DataColumn to your table that has its Expression property set to "Child(RelationName).ColumnName" or "Parent(RelationName).ColumnName" depending on the direction of the relationship.
This will give you the same effect as copying the column, but I believe it only evaluates it lazily. So maybe it will give you what you need.
There is an example here of how this works. The example uses the Sum aggregate function, but you just need to reference the column name and it will duplicate it in your DataTable
myDataSet.Relations.Add(
"Orders2OrderLines",
myDataSet.Tables["Orders"].Columns["OrderID"],
myDataSet.Tables["OrderLines"].Columns["OrderID"]);
ordersTable.Columns.Add("OrderTotal", typeof(decimal), "Sum(Child(Orders2OrderLines).ExtendedPrice)");
HTH
The problem is caused by the c# can not reuse the object instance created and uses it on multiples DataTables. For this it is necessary to create a new object DataCollumn for each loop iteration.
foreach (DataTable table in DATASET.Tables)
{
DataColumn yourDataCollumn = new DataColumn("Name of DataCollumn", typeof(Your data type));
// your logic here
}
Hope it's help...
I used the below to merge two tables using mostly LINQ and only looping through the rows at the end. I wouldn't call it pretty but it does work. Using the join to prevent some of the assumptions listed above.
DataTable tableOne = getTableOne();
DataTable tableTwo = getTableTwo();
var oneColumns = tableOne.Columns.Cast<DataColumn>()
.Select(p => new Column(p.ColumnName, DataType))
.ToArray();
var twoColumns = tableTwo.Columns.Cast<DataColumn>()
.Select(p => new DataColumn(p.ColumnName, p.DataType))
.ToArray();
var matches = (from a in tableOne.AsEnumerable()
join b in tableTwo.AsEnumerable() on a["column_name"] equals b["column_name"]
select a.ItemArray.Concat(b.ItemArray)).ToArray();
DataTable merged = new DataTable();
merged.Columns.AddRange(oneColumns);
merged.Columns.AddRange(twoColumns);
foreach (var m in matches) { merged.Rows.Add(m.ToArray()); }
No looping required , Refer this , Hope this should solve your problem...
DataTable dt = new DataTable();
//fill the dt here
DataTable dt2 = new DataTable();
string[] strCols = {"Column Name to copy"};
dt2 = dt.DefaultView.ToTable("newTableName", false, strCols);
I have a DataTable imported from Excel file.
Data i need is only unique from specific columns of the DataTable.
The unique data i meant is like when a command DISTINCT is used in SQL Select Query.
I want to get the list of the unique data from the DataTable Column and put them into List
I think LinQ can be used for this matter but i'm not so familiar with it.
I was thinking of code like this below
var data is from MyDataTable
where MyDataTable.ColumnName = "SpecificColumn"
select MyDataTable["SpecificColumn"]).UniqueData;
List<string> MyUniqueData = new List<string>();
foreach(object obj in data)
{
if(MyUniqueData.NotContain(obj))
MyUniqueData.add(obj);
}
I hope someone can drop off some knowledge to me.
var unique = data.Distinct().ToList();
What you're looking for is .Distinct(). See MSDN documentation here. You can specify your own comparer if you need something specific and it will return only unique records.
If you have a Datatable or DataView, inorder to get unique records from a column, you have to write this.
this would be simple.
DataTable dtNew = dt.DefaultView.ToTable(true, "ColName"); // for Datatable
DataTable dtnew= dv.ToTable(true, "ColName"); // for DataView
how to copy only the columns in a DataTable to another DataTable?
DataTable.Clone() should do the trick.
DataTable newTable = originalTable.Clone();
If only the columns are required then DataTable.Clone() can be used. With Clone function only the schema will be copied. But DataTable.Copy() copies both the structure and data
E.g.
DataTable dt = new DataTable();
dt.Columns.Add("Column Name");
dt.Rows.Add("Column Data");
DataTable dt1 = dt.Clone();
DataTable dt2 = dt.Copy();
dt1 will have only the one column but dt2 will have one column with one row.
Datatable.Clone is slow for large tables. I'm currently using this:
Dim target As DataTable =
New DataView(source, "1=2", Nothing, DataViewRowState.CurrentRows)
.ToTable()
Note that this only copies the structure of source table, not the data.
If you want the structure of a particular data table(dataTable1) with column headers (without data) into another data table(dataTable2), you can follow the below code:
DataTable dataTable2 = dataTable1.Clone();
dataTable2.Clear();
Now you can fill dataTable2 according to your condition. :)
If you want to copy the DataTable to another DataTable of different Schema Structure then you can do this:
Firstly Clone the first DataType so that you can only get the structure.
Then alter the newly created structure as per your need and then copy the data to newly created DataTable
.
So:
Dim dt1 As New DataTable
dt1 = dtExcelData.Clone()
dt1.Columns(17).DataType = System.Type.GetType("System.Decimal")
dt1.Columns(26).DataType = System.Type.GetType("System.Decimal")
dt1.Columns(30).DataType = System.Type.GetType("System.Decimal")
dt1.Columns(35).DataType = System.Type.GetType("System.Decimal")
dt1.Columns(38).DataType = System.Type.GetType("System.Decimal")
dt1 = dtprevious.Copy()
Hence you get the same DataTable but revised structure
The DataTable.Clone() method works great when you want to create a completely new DataTable, but there might be cases where you would want to add the schema columns from one DataTable to another existing DataTable.
For example, if you've derived a new subclass from DataTable, and want to import schema information into it, you couldn't use Clone().
E.g.:
public class CoolNewTable : DataTable {
public void FillFromReader(DbDataReader reader) {
// We want to get the schema information (i.e. columns) from the
// DbDataReader and
// import it into *this* DataTable, NOT a new one.
DataTable schema = reader.GetSchemaTable();
//GetSchemaTable() returns a DataTable with the columns we want.
ImportSchema(this, schema); // <--- how do we do this?
}
}
The answer is just to create new DataColumns in the existing DataTable using the schema table's columns as templates.
I.e. the code for ImportSchema would be something like this:
void ImportSchema(DataTable dest, DataTable source) {
foreach(var c in source.Columns)
dest.Columns.Add(c);
}
or, if you're using Linq:
void ImportSchema(DataTable dest, DataTable source) {
var cols = source.Columns.Cast<DataColumn>().ToArray();
dest.Columns.AddRange(cols);
}
This was just one example of a situation where you might want to copy schema/columns from one DataTable into another one without using Clone() to create a completely new DataTable. I'm sure I've come across several others as well.