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DataTableReader.IsDBNull Method

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

Namespace:  System.Data
Assembly:  System.Data (in System.Data.dll)

public override bool IsDBNull(
	int ordinal
)

Parameters

ordinal
Type: System.Int32
The zero-based column ordinal

Return Value

Type: System.Boolean
true if the specified column value is equivalent to DBNull; otherwise, false.

Implements

IDataRecord.IsDBNull(Int32)

ExceptionCondition
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 .

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.

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.


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();
    }
}


.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
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