Question

Okay, so. I’ve got a database which has a column of timestamps. The start of the “day” is 7am. So, say for today, it would start at 0700 on 6/25/12, and end at 0700 on 6/26/12. I’m needing to do calculations within that 24 hour time span. Now, I’m thinking of doing a query that gets all information starting at 0700 + 24 hours, but I’m not 100% on how to phrase said query. Thanks for any and all help.

Answer 1

Caveat – code done from the top of my head, without Visual Studio, and without proper error handling, but this should show you how to set the necessary parameter values correctly, using a parameterized query. This may contain syntax errors, but again, it should show you enough to get you going. I added comments to explain the relevant code.

private System.Data.DataTable ExecuteSql(DateTime BusinessDate)
{

    System.Data.DataTable ReturnValue = new System.Data.DataTable;
    string sql = "Select * From myTable WHERE TimestampColumn >= @StartDate AND TimestampColumn < @EndDate";
    System.Data.OleDb.OleDbCommand cmd = new System.Data.OleDb.OleDb.Command(connectionString, sql);

    // For start date, we can't assume the user has passed in a date with a 
    // midnight time, so first, use DateTime.Date to get JUST the date at midnight, 
    // then add 7 hours to get to the desired start time.
    // For example, if the calling code had passed in 1/1/2001 8:00 AM we would use
    // the .Date property to get it to 1/1/2001 12:00 AM
    // and then add 7 hours.

    cmd.Parameters.Add(@StartDate, BusinessDate.Date.AddHours(7));

    // The end date - same logic, but instead of adding 7 hours, add 31 
    // (24 hours + 7 hours = 31 hours)

    cmd.Parameters.Add(@EndDate, BusinessDate.Date.AddHours(31));  // 24 + 7
    System.Data.OleDb.OleDbDataAdapter ad = new System.Data.OleDb.OleDbDataAdapter(cmd);
    ad.Fill(ReturnValue)    

    return ReturnValue;
}