/// <summary>
/// The GetOrderIDs() method retrieves all the OrderID values from the Orders table.
/// </summary>
/// <returns>A list of all the OrderIDs</returns>
public static List <int> GetOrderIDs()
{
// Local variables
List <int> ordIDs = new List <int>(); // Empty list for storing the order ID values
// Open a connection to the database
SqlConnection con = NorthwindDB.GetConnection();
// Define the SQL statement for retrieving the OrderIDs
string selectStatement = "SELECT OrderID " +
"FROM Orders " +
"ORDER BY OrderID";
// Create the SqlCommand object
SqlCommand cmd = new SqlCommand(selectStatement, con);
// Try executing the query. If successful, loop through the results and populate
// the list orderIDs.
try
{
con.Open();
SqlDataReader reader = cmd.ExecuteReader();
while (reader.Read()) // Loop through all the results
{
ordIDs.Add((int)reader["OrderID"]);
}
}
// If unsuccessful, throw the exception
catch (SqlException ex) // This is the only type of exception that can result
{
throw ex;
}
// In either case, close the connection
finally
{
con.Close();
}
return(ordIDs);
}
/// <summary>
/// The UpdateShippedDate() method updates the ShippedDate in the Orders table,
/// for the order specified by the ord parameter.
/// </summary>
/// <param name="ord">The order to be updated</param>
/// <param name="newShippedDate">The new ShippedDate for the order</param>
/// <returns>true if successful, otherwise false</returns>
public static bool UpdateShippedDate(Order ord, DateTime?newShippedDate)
{
// The new ShippedDate will always be either a valid date or null, as it is obtained from
// a DateTimePicker on the main form, so invalid dates cannot be entered.
if (newShippedDate.HasValue)
{
// If the new ShippedDate is not null, it must be on or after the OrderDate,
// and on or before the RequiredDate, if these dates are non-null.
// Only the date portion of the DateTime value needs to be considered, and not
// the time. "DateTime?" values must be typecase to "DateTime" before using .Date.
if ((!ord.OrderDate.HasValue || (((DateTime)newShippedDate).Date >= ((DateTime)ord.OrderDate).Date)) &&
(!ord.RequiredDate.HasValue || (((DateTime)newShippedDate).Date <= ((DateTime)ord.RequiredDate).Date)))
{
// Open the database connection
SqlConnection con = NorthwindDB.GetConnection();
// Create the SQL update statement and SqlCommand object.
//
// Concurrency: use "last-in" concurrency here; i.e., this application is
// allowed to update the ShippedDate even if the record has been updated by
// another user since the data was read. It is very unlikely that different
// users would try to update the ShippedDate to different values simultaneously.
string updateStatement = "UPDATE Orders " +
"SET ShippedDate = @NewShippedDate " +
"WHERE OrderID = @OrderID";
SqlCommand cmd = new SqlCommand(updateStatement, con);
cmd.Parameters.AddWithValue("@NewShippedDate", ((DateTime)newShippedDate).ToString("yyyy-MM-dd"));
cmd.Parameters.AddWithValue("@OrderID", ord.OrderID);
// Try executing the query.
try
{
con.Open();
int count = cmd.ExecuteNonQuery(); // Returns the number of rows updated (will be either 0 or 1 here)
if (count > 0)
{
return(true);
}
else
{
return(false);
}
}
// If unsuccessful, throw the exception
catch (SqlException ex)
{
throw ex;
}
// In either case, close the database connection
finally
{
con.Close();
}
}
else
{
// The new ShippedDate is invalid. Throw an exception to indicate this.
throw new Exception("The Shipped Date must be no earlier than the Order Date, and " +
"no later than the Required Date.");
}
}
else
{
// The new ShippedDate is null, and will be updated to NULL in the database.
// This could happen if the ShippedDate was entered incorrectly and nees to
// be reset.
// Open a connection to the database
SqlConnection con = NorthwindDB.GetConnection();
// Create the SQL update statement and SqlCommand object.
// As above, use "last-in" concurrency.
string updateStatement = "UPDATE Orders " +
"SET ShippedDate = NULL " +
"WHERE OrderID = @OrderID";
// Create the SqlCommand object
SqlCommand cmd = new SqlCommand(updateStatement, con);
cmd.Parameters.AddWithValue("@OrderID", ord.OrderID);
// Try executing the query.
try
{
con.Open();
int count = cmd.ExecuteNonQuery(); // Returns the number of rows updated (will be either 0 or 1 here)
if (count > 0)
{
return(true);
}
else
{
return(false);
}
}
// If unsuccessful, throw the exception
catch (SqlException ex)
{
throw ex;
}
// In either case, close the database connection
finally
{
con.Close();
}
}
}