While converting some Access queries to T-SQL, I came across the Access function IIf. I read the documentation here and understand it takes 3 parameters: the expression, the if true, and the if false. What I have yet to find is if the "false" param is required? And if a false is not provided, what is the behavior?

CodePudding user response：

It's IIf, not IFF. All arguments are required in VBA and textbox expressions and both must be calculatable (no error result such as DivBy0) because both parts will be calculated - if either errors, the entire expression errors. The IIf() in query works differently - 'falsepart' calculates only if 'truepart' fails and if 'falsepart' is not provided, expression returns Null if 'truepart' fails.

Try some expressions and see what happens. One for testing: IIf(1=2,"T").

CodePudding user response：

Yes, it's required, it's actually like an if else statement.

i.e an action occurs if the condition is fulfilled, and another action occurs if condition is not fulfilled