CODEWITHSUNDEEP
c#.netdatetimedatatablenull
soldieraman
soldieraman

Reputation: 2688

Best way to check if column returns a null value (from database to .net application)

I have a table with a DateTime column the column can have NULL values

Now I connect to the database using an ODBC connection and get the value into a DataTable in .net / c#.

I am able to check it for NULL by going

if(String.IsNullOrEmpty(table.rows[0][0].ToString())
{
     //Whatever I want to do
}

Is String.IsNullOrEmpty the correct way to check for null values.

Upvotes: 37

Views: 148039

Answers (6)

priyanka
priyanka

Reputation: 159

If we are using EF and reading the database element in while loop then,

   using( var idr = connection, SP.......)
   {
       while(idr.read())
       {
          if(String.IsNullOrEmpty(idr["ColumnNameFromDB"].ToString())
          //do something
       }
   }

Upvotes: 0

Marcin Seredynski
Marcin Seredynski

Reputation: 7167

System.Convert.IsDbNull][1](table.rows[0][0]);

IIRC, the (table.rows[0][0] == null) won't work, as DbNull.Value != null;

Upvotes: 4

Mariano Desanze
Mariano Desanze

Reputation: 8161

Just use DataRow.IsNull. It has overrides accepting a column index, a column name, or a DataColumn object as parameters.

Example using the column index:

if (table.rows[0].IsNull(0))
{
    //Whatever I want to do
}

And although the function is called IsNull it really compares with DbNull (which is exactly what you need).

What if I want to check for DbNull but I don't have a DataRow? Use Convert.IsDBNull.

Upvotes: 12

Rabbi
Rabbi

Reputation: 4722

Just check for

if(table.rows[0][0] == null)
{
     //Whatever I want to do
}

or you could

if(t.Rows[0].IsNull(0))
{
     //Whatever I want to do
}

Upvotes: -6

jspcal
jspcal

Reputation: 51944

row.IsNull("column")

Upvotes: 1

jball
jball

Reputation: 25024

Use DBNull.Value.Equals on the object without converting it to a string.

Here's an example:

   if (! DBNull.Value.Equals(row[fieldName])) 
   {
      //not null
   }
   else
   {
      //null
   }

Upvotes: 91

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