I've uploaded data to a datatable from a excel file. Whats the best way to check empty rows in datatable. NB: Need solution for Visual Studio 2005. Cant use linq.
foreach (DataRow row in result.Rows)
{
//check if row is empty
//if not continue processing data
//else remove the row from datatable
}
Currently the solution in my mind is inside foreach loop, put another foreach loop and check each column. If all columns are null, remove the row from datatable.
Is there any other best method. Does the above method takes more time to execute as there is another for each loop. There will be lots of rows in the datatable.
Edited:
I've got one code:
private bool checkIfRowEmpty(DataRow row)
{
var r = (DataRow)row;
int emptyCount = 0;
int itemArrayCount = r.ItemArray.Length;
foreach (var i in r.ItemArray) if (string.IsNullOrWhiteSpace(i.ToString())) emptyCount++;
if (emptyCount == itemArrayCount) return false;
else return true;
}
Is this okay? Or should I use any solution from below? Which one is good?
Here is one approach - to iterate through all rows and all columns
DataTable table = new DataTable();
List<int> rowsToRemove = new List<int>();
for (int i = 0; i < table.Rows.Count; i++)
{
DataRow row = table.Rows[i];
foreach (DataColumn col in row.Table.Columns)
{
bool skip = false;
if (row[col] != null)
{
//this column is not null, so mark skip flag as true
skip = true;
}
if (skip)
//this row should be skipped because it has at least one column that isn't null
break;
else
rowsToRemove.Add(i);
//mark this row's index for deletion
}
}
//loop through list in reverse order and remove rows by their index
for (int i = rowsToRemove.Count; i > 0; i--)
table.Rows.RemoveAt(i);
Best solution I can think of is the following one:
public bool IsRowEmpty(DataRow row)
{
if (row == null)
return true;
foreach(var value in row.ItemArray)
{
if (value != null)
return false;
}
return true;
}
Then from your main code:
foreach (DataRow row in result.Rows)
{
if(!IsRowEmpty(row))
{
// Row is not empty.
}
}
Hello,
You can simply achive this using DataView : like this -
DataView dv = yourTable.DefaultView;
dv.Sort = "column_1,column_2";
DataTable dtNew = dv.ToTable(true, "column_1", "column_2",...,"column_n"); // please mention all columns here
dtNew.Rows.RemoveAt(0);
Related
Following issue:
I have a datatable and a list which contains specific values.
routIds = col1Items.Distinct().ToList();
String searchValue = String.Empty;
int rowIndex = -1;
for (int i = 0; i < routIds.Count; i++)
{
searchValue = routIds[i];
foreach (DataGridViewRow row in form1.dataGridView5.Rows)
{
if (row.Cells[form1.routingIdBox.Text].Value != null) // Need to check for null if new row is exposed
{
if (row.Cells[form1.routingIdBox.Text].Value.ToString().Equals(searchValue))
{
rowIndex = row.Index;
foreach (DataGridViewColumn column in form1.dataGridView5.Columns)
dtRout.Columns.Add(column.Name);
for (int k = 0; k < form1.dataGridView5.Rows.Count; k++)
{
dtRout.Rows.Add();
for (int j = 0; j < form1.dataGridView5.Columns.Count; j++)
{
datTable.Rows[k][j] = form1.dataGridView5.Rows[rowIndex].Cells[j].Value;
}
}
}
}
}
}
I want to search the first column from my datagridview and check if it matches a specific value (from my array - routIds). If yes then I want to add the whole row into a datatable but I don't know how this works exactly. Tried around but I get exceptions (specific row not found).
Assuming you have a DataTable as your underlying DataSource. I would not iterate through the DataGridViewRows.
DataTable dataSource = dataGridView.DataSource as DataTable; // if it is a DataTable. If not, please specify in your question
// let's make a DataTable, which is a copy of your DataSource
DataTable dataTableFoundIds = new DataTable();
foreach (DataColumn column in dataSource.Columns)
dataTableFoundIds.Columns.Add(column.ColumnName, column.DataType);
// iterate through your routeIds
foreach (int id in routeIds)
{
var row = dataSource.AsEnumerable().FirstOrDefault(item => item["col1"].Equals(id)); // take the first row in your DataSource that matches your routeId
if (row != null)
{
dataTableFoundIds.Rows.Add(row.ItemArray); // if we find something, insert the whole row of our source table
}
}
Hope this helps!
UPDATE: if you want to find all occurances:
foreach (int id in routeIds)
{
var rows = dataSource.AsEnumerable().Where(item => item["col1"].Equals(id)); // take all rows in your DataSource that match your routeId
foreach(var row in rows)
{
dataTableFoundIds.Rows.Add(row.ItemArray); // if we find something, insert the whole row of our source table
}
}
I have two Janus GridEXs. When an specific button is clicked, I want to add rows of first grid to another grid; but I want to check that already these rows do'nt exist in the second grid, so I used this code block with linq:
DataTable dtSelectedRows = new DataTable();
dtSelectedRows = firstGrid.GetDataSource().Clone();
foreach (GridEXRow row in rows)
{
DataRow dr = ((DataRowView)row.DataRow).Row;
if (dtSelectedRows.AsEnumerable().Count() > 0)
{
if (dtSelectedRows.AsEnumerable().Where(t => t.Field<Int32>("myColumn") == Convert.ToInt32(dr["myColumn"])).Count() == 0)
{
dtSelectedRows.ImportRow(dr);
}
}
else
dtSelectedRows.ImportRow(dr);
}
}
secondGrid.SetDataSource(dtSelectedRows);
but unfortunately it did'nt work and dtSelectedRows is always empty. So I forced to rewrite the block as:
GridEXRow[] rows = firstGrid.GetCheckedRows();
DataTable dtSelectedRows = new DataTable();
dtSelectedRows = firstGrid.GetDataSource().Clone();
foreach (GridEXRow row in rows)
{
if (row.RowType == Janus.Windows.GridEX.RowType.Record)
{
DataRow dr = ((DataRowView)row.DataRow).Row;
bool rowExists = false;
foreach (DataRow r in dtSelectedRows.Rows)
{
if (Convert.ToInt32(r["myColumn"]) == Convert.ToInt32(dr["myColumn"]))
{
rowExists = true;
break;
}
}
if (!rowExists)
dtSelectedRows.ImportRow(dr);}
}
secondGrid.SetDataSource(dtSelectedRows);
and fortunately it just worked. So how can I correct the first code block?
try this :
dtSelectedRows = firstGrid.GetDataSource().AsEnumerable().ToList();
instead of :
dtSelectedRows = firstGrid.GetDataSource().Clone();
This question already has answers here:
How do I loop through items in a list box and then remove those item?
(8 answers)
Closed 9 years ago.
I have for-each loop in which the data row is updated so the exception ,Collection was modified; enumeration operation might not execute is generated. any way to fix it? i have seen To-List function but it is not working with data row , here is my code:
foreach (DataRow row in dataTable.Rows) {
temp = row[0].ToString();
foreach (DataRow rows in dataTable.Rows) {
if (temp == rows[0].ToString()) {
tempdatatable.Rows.Add(row[0],row[1]);
dataTable.Rows.Remove(rows);
//Update happens here
}
tempdatatable.DefaultView.Sort = "gscitations DESC";
dataGridView1.DataSource = tempdatatable;
}
}
You cannot modify collection while enumerating it using Enumerator, which is happening behind the scene of the foreach statement (MDSN link).
One possible way to solve this problem is to collect rows to be deleted in the first enumeration and than remove them in the separate loop like this:
var rowsToDelete = new List<DataRow>();
foreach (DataRow row in dataTable.Rows)
{
temp = row[0].ToString();
foreach (DataRow rows in dataTable.Rows)
{
if (temp == rows[0].ToString())
{
tempdatatable.Rows.Add(row[0],row[1]);
rowsToDelete.Add(rows);
}
tempdatatable.DefaultView.Sort = "gscitations DESC";
dataGridView1.DataSource = tempdatatable;
}
}
rowsToDelete.ForEach( x => dataTable.Rows.Remove(x) );
You can also replace foreach loop with for, but you need to do extra work properly handling the current index while deleting the elements.
Try this :
for (int i = 0; i < dataTable.Rows.Count; i++)
{
var tempRow = dataTable.Rows[i];
var temp = dataTable.Rows[i][0];
for (int j = 0; j < dataTable.Rows.Count; j++)
{
DataRow rows = dataTable.Rows[j];
if (temp == rows[0].ToString())
{
tempdatatable.Rows.Add(tempRow[0], tempRow[1]);
dataTable.Rows.Remove(rows); //Update happen here
}
tempdatatable.DefaultView.Sort = "gscitations DESC";
dataGridView1.DataSource = tempdatatable;
}
}
I would say that you should make a separate table of entries, and instead of calling datatable.Rows.Remove(rows), add the row "rows" to this other table. Then, whenever row or rows iterates, you run an if statement to check if its been "deleted", i.e., in the list of deleted rows. After the enumeration is over, you can then delete those rows permanently from the table.
EDIT:
Here's the code implementation:
DataTable duplicates = dataTable;
duplicates.Rows.Clear(); /* Produces an empty duplicate of the
dataTable table to put the duplicates in */
foreach (DataRow row in dataTable.Rows)
{
if (!duplicates.Rows.Contains(row))
{
temp = row[0].ToString();
foreach (DataRow rows in dataTable.Rows)
{
if (temp == rows[0].ToString()&&!duplicates.Rows.Contains(rows)) //need unique key
{
tempdatatable.Rows.Add(row[0],row[1]);
}
tempdatatable.DefaultView.Sort = "gscitations DESC";
dataGridView1.DataSource = tempdatatable;
}
}
}
foreach (DataRow row in duplicates.Rows)
{
dataTable.Rows.Remove(row);
}
if you don't have a unique key, you can try switching !duplicates.Rows.Contains(/*specific row*/) for duplicates.Rows.IndexOf(/*specific row*/)>0. That should provide an adequate substitute.
When I call dataSet.GetXml() I don't get any xml returned for columns with null or blank values. Is there a simple, efficient way to get around this? An example of the problem below. Notice how a2 is missing from the second results section.
<results>
<a1>test1</a1>
<a2>test2</a2>
<a3>test3</a3>
</results>
<results>
<a1>Atest1</a1>
<a3>Atest3</a3>
</results>
The problem is detailed in this Microsoft KB article: http://support.microsoft.com/default.aspx?scid=kb;EN-US;Q317961. See this previous SO question for more detail: DataSet.GetXml not returning null results.
I don't think there is a good solution to your direct question. Given context, there may be another way to approach the problem though.
One solution that worked for me.
First clone the DataTable, make all columns of type string, replace all null values with string.empty, then call GetXml on a new DataSet.
DataTable dtCloned = dt.Clone();
foreach (DataColumn dc in dtCloned.Columns)
dc.DataType = typeof(string);
foreach (DataRow row in dt.Rows)
{
dtCloned.ImportRow(row);
}
foreach (DataRow row in dtCloned.Rows)
{
for (int i = 0; i < dtCloned.Columns.Count; i++)
{
dtCloned.Columns[i].ReadOnly = false;
if (string.IsNullOrEmpty(row[i].ToString()))
row[i] = string.Empty;
}
}
DataSet ds = new DataSet();
ds.Tables.Add(dtCloned);
string xml = ds.GetXml();
I have been searching the whole world for a solution of writing null fields to XML using DataSet.WriteXML(). I found that following works in a performance optimized way. I have created a function for your convenience. Change your dataset tables one after the other by calling the following function and replacing the tables.
private DataTable GetNullFilledDataTableForXML(DataTable dtSource)
{
// Create a target table with same structure as source and fields as strings
// We can change the column datatype as long as there is no data loaded
DataTable dtTarget = dtSource.Clone();
foreach (DataColumn col in dtTarget.Columns)
col.DataType = typeof(string);
// Start importing the source into target by ItemArray copying which
// is found to be reasonably fast for nulk operations. VS 2015 is reporting
// 500-525 milliseconds for loading 100,000 records x 10 columns
// after null conversion in every cell which may be usable in many
// circumstances.
// Machine config: i5 2nd Gen, 8 GB RAM, Windows 7 64bit, VS 2015 Update 1
int colCountInTarget = dtTarget.Columns.Count;
foreach (DataRow sourceRow in dtSource.Rows)
{
// Get a new row loaded with data from source row
DataRow targetRow = dtTarget.NewRow();
targetRow.ItemArray = sourceRow.ItemArray;
// Update DBNull.Values to empty string in the new (target) row
// We can safely assign empty string since the target table columns
// are all of string type
for (int ctr = 0; ctr < colCountInTarget; ctr++)
if (targetRow[ctr] == DBNull.Value)
targetRow[ctr] = String.Empty;
// Now add the null filled row to target datatable
dtTarget.Rows.Add(targetRow);
}
// Return the target datatable
return dtTarget;
}
if (ds != null && ds.Tables.Count > 0 && ds.Tables[0].Rows.Count == 0)
{
foreach (DataTable dt in ds.Tables)
{
foreach (DataColumn dc in dt.Columns)
{
dc.DataType = typeof(String);
}
}
DataRow dr = ds.Tables[0].NewRow();
for (int i = 0; i < dr.ItemArray.Count(); i++)
{
dr[i] = string.Empty;
}
ds.Tables[0].Rows.Add(dr);
}
I built an application which displays the records from database in the window and checks the the database for new records every couple of seconds. The problem is that the window blinks each time I check for new records and I want to fix it. I have tried to compare the old datatable with the new one and refresh only if they are different.
Does anyone know what is the best practice for such cases? I tried to do it the following way but it doesn't work:
private bool GetBelongingMessages()
{
bool result = false;
DataTable dtTemp = OleDbWorks.GetBelongingMessages(currentCallID);
if(dtTemp != dtMessages)
{
dtMessages = dtTemp;
result = true;
}
else
{
result = false;
}
return result;
}
First off, it's important to recognize that what you're comparing in your code is the references of the datatables, not the contents of the datatables. In order to determine if both datatables have the same contents, you're going to have to loop through all of the rows and columns and see if they're equal:
//This assumes the datatables have the same schema...
public bool DatatablesAreSame(DataTable t1, DataTable t2) {
if (t1.Rows.Count != t2.Rows.Count)
return false;
foreach (DataColumn dc in t1.Columns) {
for (int i = 0; i < t1.Rows.Count; i++) {
if (t1.Rows[i][dc.ColumnName] != t2.Rows[i][dc.ColumnName]) {
return false;
}
}
}
return true;
}
I've been trying to find a way to do DataTable comparison for a while and ended up writing up my own function, here is what I got:
bool tablesAreIdentical = true;
// loop through first table
foreach (DataRow row in firstTable.Rows)
{
foundIdenticalRow = false;
// loop through tempTable to find an identical row
foreach (DataRow tempRow in tempTable.Rows)
{
allFieldsAreIdentical = true;
// compare fields, if any fields are different move on to next row in tempTable
for (int i = 0; i < row.ItemArray.Length && allFieldsAreIdentical; i++)
{
if (!row[i].Equals(tempRow[i]))
{
allFieldsAreIdentical = false;
}
}
// if an identical row is found, remove this row from tempTable
// (in case of duplicated row exist in firstTable, so tempTable needs
// to have the same number of duplicated rows to be considered equivalent)
// and move on to next row in firstTable
if (allFieldsAreIdentical)
{
tempTable.Rows.Remove(tempRow);
foundIdenticalRow = true;
break;
}
}
// if no identical row is found for current row in firstTable,
// the two tables are different
if (!foundIdenticalRow)
{
tablesAreIdentical = false;
break;
}
}
return tablesAreIdentical;
Compared to Dave Markle's solution, mine treats two table with same records but in different orders as identical. Hope this helps whoever stumbles upon this thread again.
You have to cast objects t1.Rows[i][dc.ColumnName] and t1.Rows[i][dc.ColumnName] otherwise the statement t1.Rows[i][dc.ColumnName] != t2.Rows[i][dc.ColumnName] is always true. I modified the code the following way:
for(int i = 0; i < t1.Rows.Count; i++)
{
if((string)t1.Rows[i][1] != (string)t2.Rows[i][1])
return false;
}
and it works but it's not an elegant solution.
public Boolean CompareDataTables(DataTable table1, DataTable table2)
{
bool flag = true;
DataRow[] row3 = table2.Select();
int i = 0;// row3.Length;
if (table1.Rows.Count == table2.Rows.Count)
{
foreach (DataRow row1 in table1.Rows)
{
if (!row1.ItemArray.SequenceEqual(row3[i].ItemArray))
{
flag = false;
break;
}
i++;
}
}
else
{
flag = false;
}
return flag;
}
// here this function will gave boolean as result return true if both are same else return false if both are not same