Name

GetOrdinal

Synopsis

Int32 ordinal = DataReader.GetOrdinal(String columnName);

Retrieves the zero-based ordinal for the column with the specific name. This is useful for two reasons. First of all, many DataReader methods require the use of column ordinals, not field names. Second, access via a column ordinal is likely to perform faster. In fact, when you use a column name, ADO.NET performs a hashtable lookup behind the scenes to determine the correct column ordinal. Using GetOrdinal( ), you can perform this lookup once, rather than every time you need to access a field.

Example

The following code shows a simple example of how you might access a column using the column ordinal, even if you only know its column name:

// Perform the ordinal lookups.

int colID = r.GetOrdinal("CustomerID");

int colFirstName = r.GetOrdinal("FirstName");

int colSecondName = r.GetOrdinal("SecondName");



while (r.Read())

{

    // Use the ordinals far faster column value access.

    Console.WriteLine(r[colID].ToString());

    Console.WriteLine(r[colFirstName].ToString() + " " +

      r[colSecondName].ToString());

    Console.WriteLine();

}

Note

Columns are returned in the same order they appear in a SELECT statement.