DataTableReader.IsDBNull(Int32) Method

Definition

Namespace:

System.Data

Assemblies:

netstandard.dll, System.Data.Common.dll

Source:

DataTableReader.cs

Gets a value that indicates whether the column contains non-existent or missing values.

C#

public override bool IsDBNull(int ordinal);

Parameters

ordinal

Int32

The zero-based column ordinal.

Returns

Boolean

true if the specified column value is equivalent to DBNull; otherwise, false.

Exceptions

ArgumentOutOfRangeException

The index passed was outside the range of 0 to FieldCount - 1.

DeletedRowInaccessibleException

An attempt was made to retrieve data from a deleted row.

InvalidOperationException

An attempt was made to read or access a column in a closed DataTableReader .

Examples

The following example displays the contents of the column numbered 2 within the passed-in DataTableReader. If the value the column within a particular row is null, the code displays the text <NULL>. If the data within the column of the correct type, the example displays an error message for each row.

C#

private static void PrintColumn(DataTableReader reader)
{
    // Loop through all the rows in the DataTableReader
    while (reader.Read())
    {
        if (reader.IsDBNull(2))
        {
            Console.Write("<NULL>");
        }
        else
        {
            try
            {
                Console.Write(reader.GetString(2));
            }
            catch (InvalidCastException)
            {
                Console.Write("Invalid data type.");
            }
        }
        Console.WriteLine();
    }
}

Remarks

Call this method to see if there are null column values before calling the typed get methods (for example, GetByte, GetChar, and so on) to avoid raising an error.

Applies to