I have a DataSet where I need to find out how many rows has been changed using the following code:
dataTable1 = dataSet1.Tables["FooTable"].GetChanges();
foreach (DataRow dr in dataTable1)
{
// ...
}
DataSet has DataSet.HasRow but DataTable doesn't have such method. If there is no changed rows. changedDT1 will be a null value, causing the loop to throw exception.
How do I check if DataTable is empty? I tried Rows.Count - doesn't work...
First make sure that DataTable is not null and than check for the row count
if(dt!=null)
{
if(dt.Rows.Count>0)
{
//do your code
}
}
If dataTable1 is null, it is not an empty datatable.
Simply wrap your foreach in an if-statement that checks if dataTable1 is null.
Make sure that your foreach counts over DataTable1.Rows or you will get a compilation error.
if (dataTable1 != null)
{
foreach (DataRow dr in dataTable1.Rows)
{
// ...
}
}
Normally when querying a database with SQL and then fill a data-table with its results, it will never be a null Data table. You have the column headers filled with column information even if you returned 0 records.When one tried to process a data table with 0 records but with column information it will throw exception.To check the datatable before processing one could check like this.
if (DetailTable != null && DetailTable.Rows.Count>0)
Don't use rows.Count. That's asking for how many rows exist. If there are many, it will take some time to count them. All you really want to know is "is there at least one?" You don't care if there are 10 or 1000 or a billion. You just want to know if there is at least one. If I give you a box and ask you if there are any marbles in it, will you dump the box on the table and start counting? Of course not. Using LINQ, you might think that this would work:
bool hasRows = dataTable1.Rows.Any()
But unfortunately, DataRowCollection does not implement IEnumerable.
So instead, try this:
bool hasRows = dataTable1.Rows.GetEnumerator().MoveNext()
You will of course need to check if the dataTable1 is null first. if it's not, this will tell you if there are any rows without enumerating the whole lot.
You can also simply write
if (dt.Rows.Count == 0)
{
//DataTable does not contain records
}
This is an old question, but because this might help a lot of c# coders out there, there is an easy way to solve this right now as follows:
if ((dataTableName?.Rows?.Count ?? 0) > 0)
As from MSDN for GetChanges
A filtered copy of the DataTable that can have actions performed on it, and later be merged back in the DataTable using Merge. If no rows of the desired DataRowState are found, the method returns Nothing (null).
dataTable1 is null so just check before you iterate over it.
Sub Check_DT_ForNull()
Debug.Print WS_FE.ListObjects.Item(1).DataBodyRange.Item(1).Value
If Not WS_FE.ListObjects.Item(1).DataBodyRange.Item(1).Value = "" Then
Debug.Print WS_FE.ListObjects.Item(1).DataBodyRange.Rows.Count
End If
End Sub
This checks the first row value in the DataBodyRange for Null and Count the total rows This worked for me as I downloaded my datatable from server It had not data's but table was created with blanks and Rows.Count was not 0 but blank rows.
I use an extension. Maybe it is helpful.
public static class DataTableExtensions
{
public static bool IsNullOrEmpty(this DataTable table) => table is null || table.Rows.Count == 0;
}
bool empty = !DataTableExtensions.AsEnumerable(DataTableToCheck).Any()
