How check DataReader is NULL?

How check DataReader is NULL?

Try this way: stirng query = “SELECT ColumnA FROM MyTable WHERE ColumnB = ‘some condition'”; //… initialize connection and command and reader classes //then do: if(reader. Read()) //if there are any value(s) { if(reader. GetValue(0) !=

How do I handle NULL in DataReader?

If you do datareader[“columnName”]. ToString(); it will always give you a value that can be a empty string ( String. Empty if you need to compare). What I tend to do is replace the null values in the SELECT statement with something appropriate.

What is DBNull value in C#?

The DBNull class represents a nonexistent value. In a database, for example, a column in a row of a table might not contain any data whatsoever. That is, the column is considered to not exist at all instead of merely not having a value. A DBNull object represents the nonexistent column.

How check DataRow is null or empty in C#?

row. IsNull(column)) return false; return true; I suppose this approach looks more simple and bright. Still, it essentially checks each cell for emptiness, and lets you know whether all cells in the row are empty.

How do you deal with null values in a database?

1. IS NULL and IS NOT NULL Operators. We cannot use the comparison operators, =,<,>,<> , to test for NULL values.
2. ISNULL() Function. The ISNULL function returns the specified value if the given expression is NULL.
3. COALESCE() Function.
4. CASE Expression.
5. NULLIF() Function.

How do you retrieve null values from a database?

How to Test for NULL Values?

1. SELECT column_names. FROM table_name. WHERE column_name IS NULL;
2. SELECT column_names. FROM table_name. WHERE column_name IS NOT NULL;
3. Example. SELECT CustomerName, ContactName, Address. FROM Customers. WHERE Address IS NULL;
4. Example. SELECT CustomerName, ContactName, Address. FROM Customers.

How to check if a DataReader is null or empty?

The logic behind this is: If the field “Additional” contains text then display the info otherwise hide the field. The above code gives me this error: Any help would be greatly appreciated… if (myReader.HasRows) //The key Word is **.HasRows** { ltlAdditional.Text = “Contains data”; } else { ltlAdditional.Text = “Is null Or Empty”; }

How to handle Nulls in SQL data reader?

So in this case we’d be calling DBUtils.GetString (sqlreader (indexFirstName)) The benefit of creating static/shared methods is that you don’t have to do the same checks over and over and over… The static method (s) would contain code to check for nulls (see other answers on this page).

How to deal with sqldatareader null values in VB?

No need to check for DbNull. _ Public Function ReadString (ByVal reader As IDataReader, ByVal fieldOrdinal As Integer) As String If IsDBNull (reader (fieldOrdinal)) Then Return “” Else Return reader (fieldOrdinal) End If Return False End Function End Module

Which is the best way to check for null?

If you want to check for null and handle it (as opposed to checking for null and alerting the program that it was null) you can use the as operator with the null-coalescing operator ?? . So in my program Direct casting seems to work just fine for either nullable or non-nullable types.