What is IsDBNull?

What is IsDBNull?

The IsDBNull method tests whether the value parameter is equal to DBNull.Value. It is equivalent to the following code: C# Copy. return DBNull.Value.Equals(value);

What is the difference between Null and DBNull?

NULL represent non existance of an instance variable type. in simple word the value is null in variable. G. S. DBNull applies to database specific NULL values or we can say that DbNull is what you use when interacting with databases.

What does DBNull value return?

DBNull represents a nonexistent value returned from the database. 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.

What is IIF in VB net?

IIF returns one of two objects, depending on the evaluation of an expression. IIf(Expression As Boolean,TruePart As Object,FalsePart As Object) As Object. IIF is a function and it only specific to VB.NET, because in C# there is no IIF, so it is not the part Common Language Runtime.

What language uses IIF?

Visual Basic programming language
In computing, IIf (an abbreviation for Immediate if) is a function in several editions of the Visual Basic programming language and ColdFusion Markup Language (CFML), and on spreadsheets that returns the second or third parameter based on the evaluation of the first parameter.

How do you know if you have a DBNull?

DbNull is used to denote the fact that a variable contains a missing or nonexistent value, and it is used primarily in the context of database field values. will always fail. The only way to test for a DbNull value is to use IsDbNull.

What does the IIf () function return?

The IIF () function returns a value if a condition is TRUE, or another value if a condition is FALSE. Required. The value to test Optional. The value to return if condition is TRUE

Is there a ternary operator in C with IIF()?

C# has the? ternary operator, like other C-style languages. However, this is not perfectly equivalent to IIf (); there are two important differences. To explain the first difference, the false-part argument for this IIf () call causes a DivideByZeroException, even though the boolean argument is True.

Does IIF() short circuit?

IIf () is just a function, and like all functions all the arguments must be evaluated before the call is made. Put another way, IIf () does not short circuit in the traditional sense. On the other hand, this ternary expression does short-circuit, and so is perfectly fine: (true)?1:1/0;

How do I use IIF in a form?

Use IIf on a form or report Suppose you have a Customers table that contains a field named CountryRegion. In a form, you want to denote whether Italian is the first language of the contact. You can add a control and use IIf in its Control Source property, like so: =IIf ( [CountryRegion]=”Italy”, “Italian”, “Some other language”)