DBNull Use Tips

Tips DBNull Use Skills
　　
Easy-Moving Studio EPower2002
　　
Vb. NET, one of the changes is to remove the isnull and IsEmpty functions that are available in VB6, and provide another way to determine whether the variable is initialized, that is, the IsDBNull () method.
The IsDBNull () method takes an object as its parameter and returns a Boolean indicating whether the variable is initialized.
Dim Strmyname as String
If not IsDBNull (strmyname) Then
Strmyname= "Initialize My string"
End If
　　
In addition, VB. NET also provides the DBNull class, which is part of the System namespace. The use method is to declare a variable of type DBNull, and then the variable is used for the IS comparison operator to determine whether the given variable is initialized.
Dim Sysnull as System.DBNull
Dim Strmyname as String
If Strmyname is Sysnull Then
Strmyname= "Initialize My string"
End If