I have a stored procedure which selects the differences between rows in a table and returns a DataTable in the following format:
col1_A, col2_A, col3_A, col1_B, col2_B, col3B
I would like to split the DataTable into 2 separate DataTables so it looks like
TableA
col1
col2
col3
TableB
col1
col2
col3
This code gets me the column index.
foreach (DataColumn col in DT.Columns)
{
if (!col.ColumnName.EndsWith("B"))
tableBIndex += 1;
else
break;
}
but from here I'm not sure how to separate the rows into 2 DataTables. Any ideas on the best way to accomplish this?
This should do the trick and fill both tables in one loop:
DataColumn[] aCols = table.Columns.Cast<DataColumn>()
.Where(c => c.ColumnName.EndsWith("A"))
.Select(c => new DataColumn(c.ColumnName, c.DataType))
.ToArray();
DataColumn[] bCols = table.Columns.Cast<DataColumn>()
.Where(c => c.ColumnName.EndsWith("B"))
.Select(c => new DataColumn(c.ColumnName, c.DataType))
.ToArray();
var TableA = new DataTable();
TableA.Columns.AddRange(aCols);
var TableB = new DataTable();
TableB.Columns.AddRange(bCols);
foreach (DataRow row in table.Rows)
{
DataRow aRow = TableA.Rows.Add();
DataRow bRow = TableB.Rows.Add();
foreach (DataColumn aCol in aCols)
aRow.SetField(aCol, row[aCol.ColumnName]);
foreach (DataColumn bCol in bCols)
bRow.SetField(bCol, row[bCol.ColumnName]);
}
I'd recommend creating two new tables and copying out values like this.
DataTable one = new DataTable();
DataTable two = new DataTable();
foreach (DataColumn col in DT.Columns)
{
if (!col.ColumnName.EndsWith("B"))
{
one.Columns.Add(col.ColumnName.Replace("_A", ""));
foreach (DataRow row in DT.Rows)
{
one.Rows.Add(row[col.ColumnName]);
}
}
else
{
one.Columns.Add(col.ColumnName.Replace("_B", ""));
foreach (DataRow row in DT.Rows)
{
two.Rows.Add(row[col.ColumnName]);
}
}
}
Related
I have a Dataset which contains many dataTable .
The datatables looks like as follows,
column1 column2 column3 Name
NA NA NA Ivan
Now I want to remove columns from all datatables in the dataset where row value is 'NA'.
How can I do this using Linq if possible?
You can remove column from collecion via method Remove, and linq can only help you find desired columns.
Find desired columns and then remove them.
var dt = new DataTable();
List<DataColumn> delete = new List<DataColumn>();
foreach (DataRow row in dt.Rows)
foreach (DataColumn col in dt.Columns)
if (row[col]?.ToString() == "NA" && !delete.Contains(col))
delete.Add(col);
foreach (var col in delete)
dt.Columns.Remove(col);
I guess that you actually want to remove all string-columns of all tables where all values of all rows are NA(or na). Then this works as expected:
foreach (DataTable table in ds.Tables)
{
List<DataColumn> stringColumns = table.Columns.Cast<DataColumn>()
.Where(c => c.DataType == typeof(string))
.ToList();
var columnsAllNotAvailable = stringColumns
.Where(c => table.AsEnumerable()
.All(r => String.Equals(r.Field<string>(c), "NA", StringComparison.InvariantCultureIgnoreCase)));
foreach(DataColumn col in columnsAllNotAvailable)
table.Columns.Remove(col);
}
I am trying to do a foreach loop that stores each row from datatable1 into datatable2, so foreach row in datatable1 store the row in datatable2, this is what I have so far:
public static DataTable datatable2 = new DataTable();
public void createDatatable()
{
profile p = new profile();
DataTable datatable1 = p.getResults(System.Convert.ToInt32(HttpContext.Current.Session["ID"]));
foreach (DataRow dr in datatable1.Rows)
{
datatable2 = datatable1.Copy();
}
}
This just copies the columns too which I don't want, I just want each row stored from datatable2 into datatable1
I assume dataTable1 & dataTable2 has same schema (same number of columns with similar datatype). Don't use .Copy(). Use Rows.Add to copy content as follows,
foreach (DataRow dr in dataTable1.Rows) {
dataTable2.Rows.Add(dr.ItemArray);
}
I have created 3 datatables
var dt1= new DataTable();
var dt2= new DataTable();
var dt3= new DataTable();
Then i loop
foreach (DataRow row1 in dt1.Rows)
{
dt3.Rows.Add(row1.ItemArray);
foreach (DataRow row2 in dt2.Rows)
{
var Id2 = row1["Id"];
var Id1= row2["Id"];
if (Id1 == Id2)
{
dt3.rows["Name"] = "" ; // doesnt work
}
}
}
As you can see that i loop on 2 datatables. Then in inner loop i check if the records matches. Now if the record matches then i want to update column "Name" on dt3 datatable.
I tried using
dt3.rows["Name"] = "" ;
But this doesnt work. I know the reason that its because i again need to loop on dt3 datatable and
assign values to column in that loop. But not sure how to do it and if there is even more better solution. I mean we can find id in dt3 datatable and then update value. But not sure how to do it
Is there more intelligent solution than looping on 2 table?
The first foreach is not needed. A simple DataTable.Copy will bring all the data and structure from the original table in the destination table. Then looping on the second table and Select on the third to find the matching rows and clear the name.
dt3 = dt1.Copy();
foreach (DataRow row2 in dt2.Rows)
{
DataRow[] match = dt3.Select("ID=" + row2["ID"].ToString());
if(match.Lenght > 0)
match[0]["Name"] = "" ;
}
Not sure if this is more performant from the other answers. Need to be tested
dt3.rows doesn't work, you want to change the name of the row that you have added now. This should work:
foreach (DataRow row1 in dt1.Rows)
{
DataRow newRow = dt3.Rows.Add(row1.ItemArray);
foreach (DataRow row2 in dt2.Rows)
{
var Id2 = row1["Id"];
var Id1 = row2["Id"];
if (Id1 == Id2)
{
newRow["Name"] = "new Name";
}
}
}
Try this:
foreach (DataRow row1 in dt1.Rows)
{
var row = dt3.Rows.Add(row1.ItemArray);
foreach (DataRow row2 in dt2.Rows)
{
var Id2 = row1["Id"];
var Id1= row2["Id"];
if (Id1 == Id2)
{
row["Name"] = ""; //maybe works
}
}
}
How about,
dt2Lookup = new HashSet(
dt2.AsEnumerable().Select(row => row.Field<int>("Id")));
dt3 = dt1.Clone();
forreach (var row In dt1.AsEnumerable())
{
var newRow = dt3.Rows.Add(row.ItemArray)
if (dt2lookup.Contains(row.Field<int>("Id"))
{
newRow.SetField("Name", string.Empty);
}
}
The HashSet should provide good lookup performance.
dt3 = dt1.Copy();
var RowDictionary = dt3.Rows.OfType<DataRow>().ToDictionary(dr => dr["ID"].ToString());
//replace by Dictionary<string,List<DataRow>> in case ID is not unique and fill it with a foreach loop.
foreach (DataRow row2 in dt2.Rows)
{
DataRow Match;
if (c.TryGetValue(row2["ID"].ToString(), out Match))
{
Match["Name"] = "";
}
}
You should call:
dt3.rows[dt3.rows.Count - 1].Columns["Name"] = "" ;
I want to Delete the Multiple records from the DataTable
For example :
in my case PaperId is Repeating several Times.I want to Delete it all Duplicate records.
i have written code but loop is giving error
DataSet ds = new DataSet();
sqlDad.Fill(ds);
DataTable dt1 = new DataTable();
ds.Tables.Add(dt1);
dt1 = ds.Tables[0];
DataTable dt2 = new DataTable();
dt2 = dt1;
List<DataRow> rowsToDelete = new List<DataRow>();
foreach(DataRow dr in ds.Tables[0].Rows)
{
int r = ds.Tables[0].Columns.Count;
string x = dr.ItemArray[0].ToString();
int counter = 0;
foreach (DataRow dr1 in ds.Tables[0].Rows)
{
if (x == dr1.ItemArray[0].ToString())
{
counter++;
}
if (counter > 1)
{
rowsToDelete.Add(dr1);
foreach (DataRow row in rowsToDelete)
{
dt2.Rows.Remove(row);
}
dt2.AcceptChanges();
rowsToDelete.Clear();
}
}
Using the DefaultView of the DataTable and setting the sort order on the column that you don't want repeats to appear. You could loop over the rows and delete all the rows after the first one
// Work on the first table of the DataSet
DataTable dt1 = ds.Tables[0];
// No need to work if we have only 0 or 1 rows
if(dt1.Rows.Count <= 1)
return;
// Setting the sort order on the desidered column
dt1.DefaultView.Sort = dt1.Columns[0].ColumnName;
// Set an initial value ( I choose an empty string but you could set to something not possible here
string x = string.Empty;
// Loop over the row in sorted order
foreach(DataRowView dr in dt1.DefaultView)
{
// If we have a new value, keep it else delete the row
if(x != dr[0].ToString())
x = dr[0].ToString();
else
dr.Row.Delete();
}
// Finale step, remove the deleted rows
dt1.AcceptChanges();
Try This
DataRow[] rows;
rows=dataTable.Select("UserName = 'ABC'"); // UserName is Column Name
foreach(DataRow r in rows)
r.Delete();
If you want to remove the entire row from DataTable ,
try this
DataTable dt = new DataTable(); //User DataTable
DataRow[] rows;
rows = dt.Select("UserName = 'KarthiK'");
foreach (DataRow row in rows)
dt.Rows.Remove(row);
Well. I have a DataTable with multiple columns and multiple rows.
I want to loop through the DataTable dynamically basically the output should look as follows excluding the braces :
Name (DataColumn)
Tom (DataRow)
Peter (DataRow)
Surname (DataColumn)
Smith (DataRow)
Brown (DataRow)
foreach (DataColumn col in rightsTable.Columns)
{
foreach (DataRow row in rightsTable.Rows)
{
//output
}
}
I typed that out and noticed this would not work. Can someone please advice on a better way of doing this?
foreach (DataColumn col in rightsTable.Columns)
{
foreach (DataRow row in rightsTable.Rows)
{
Console.WriteLine(row[col.ColumnName].ToString());
}
}
foreach (DataRow row in dt.Rows)
{
foreach (DataColumn col in dt.Columns)
Console.WriteLine(row[col]);
}
Please try the following code below:
//Here I am using a reader object to fetch data from database, along with sqlcommand onject (cmd).
//Once the data is loaded to the Datatable object (datatable) you can loop through it using the datatable.rows.count prop.
using (reader = cmd.ExecuteReader())
{
// Load the Data table object
dataTable.Load(reader);
if (dataTable.Rows.Count > 0)
{
DataColumn col = dataTable.Columns["YourColumnName"];
foreach (DataRow row in dataTable.Rows)
{
strJsonData = row[col].ToString();
}
}
}
If you want to change the contents of each and every cell in a datatable then we need to Create another Datatable and bind it as follows using "Import Row". If we don't create another table it will throw an Exception saying "Collection was Modified".
Consider the following code.
//New Datatable created which will have updated cells
DataTable dtUpdated = new DataTable();
//This gives similar schema to the new datatable
dtUpdated = dtReports.Clone();
foreach (DataRow row in dtReports.Rows)
{
for (int i = 0; i < dtReports.Columns.Count; i++)
{
string oldVal = row[i].ToString();
string newVal = "{"+oldVal;
row[i] = newVal;
}
dtUpdated.ImportRow(row);
}
This will have all the cells preceding with Paranthesis({)