Question

Could you please look on the code below and say why this code doesn’t throw an exception when the column value is null?

DataTable table = new DataTable();
table.Columns.Add("PreviewHtml");

table.Rows.Add(new object[] { "aksdhaskldh" });
table.Rows.Add(new object[] { "129836 128o tagjk 1782 3" });
table.Rows.Add(new object[] { null });
table.Rows.Add(new object[] { "1278o36 " });


foreach (DataRow r in table.Rows)
{
     Console.WriteLine(r["PreviewHtml"].ToString());
}

Answer 1

It’s because DBNull.ToString returns an empty string.

DataColumn’s AllowDBNull property is set to true by default, otherwise you could not add null values.

Null values are converted to DBNull.Value, AutoIncrement columns are also incremented when null is passed.