Question

I have a DataTable dt with two columns FromDate and ToDate. I have two textboxes where I am entering the dates blackOutFromDate and blackOutToDate. Say, I have 7 rows inside my DataTable dt:

From Date       To Date      
8/21/2012   To  8/22/2012   
8/23/2012   To  8/24/2012   
8/25/2012   To  8/25/2012   
8/5/2012    To  8/6/2012    
8/26/2012   To  8/27/2012   
8/1/2012    To  8/2/2012    
8/3/2012    To  8/3/2012

If the value that I enter inside my text boxes CheckInDate and CheckOutDate is between any matching date range of DataTable dt, it should return the count of the noumber of rows having such match.

I am doing

foundRows = _blackOutTable.Select
                               (
                                   "(FromDate <='" +     
blackOutFromDate.ToShortDateString() + "' AND ToDate >= '" + 
blackOutFromDate.ToShortDateString() + "')"
                                   + "OR (FromDate <='" + 
blackOutToDate.ToShortDateString() + "' AND ToDate >='" + 
blackOutToDate.ToShortDateString() + "')"
                                   + "OR (FromDate >='" + 
blackOutFromDate.ToShortDateString() + "' AND FromDate <='" +     
blackOutToDate.ToShortDateString() + "')"
                                   + "OR (ToDate >= '" +   
blackOutFromDate.ToShortDateString() + "' AND ToDate <='" +     
blackOutToDate.ToShortDateString() + "')"
                               );
if (foundRows.Length == 0)
{
}

EDIT :
I am storing the DateFrom and DateTo filed inside SQl Server as

CAST(MONTH(date1) AS VARCHAR(2)) + '/' + CAST(DAY(date1) AS VARCHAR(2)) + '/' +     
CAST(YEAR(date1) AS VARCHAR(4))  [fromdate],
        CAST(MONTH(date2) AS VARCHAR(2)) + '/' + CAST(DAY(date2) AS 
VARCHAR(2)) + '/' + CAST(YEAR(date2) AS VARCHAR(4))  [todate]

blackOutFromDate and blackOutFromDate are of DateTime types.

But it’s not returning the correct values. There is some problem with the select expression. What can I do to fix this?

Answer 1

This is the DataTable.Select syntax for DateTimes:

foundRows = _blackOutTable.Select("FromDate >= #2012-07-13#")

So you need to use String.Format to put your date variable into that string.

Edit: Since your datetimes are converted to varchar and you cannot change that, you need to parse them back to datetime. I would recommend to use Linq-To-DataSet:

DataTable tblFiltered;
var invCulture=System.Globalization.CultureInfo.InvariantCulture;
var filteredRows = _blackOutTable.AsEnumerable()
    .Where(r => DateTime.Parse(r.Field<String>("FromDate"), invCulture) >= blackOutFromDate
             && DateTime.Parse(r.Field<String>("ToDate"),   invCulture) <= blackOutToDate);

if (filteredRows.Any())
{
    tblFiltered = filteredRows.CopyToDataTable();
}

You can use foreach to enumerate all rows or use CopyToDataTable to create a new DataTable from the filtered DataRows.