How to use IF statement inside WITH?

Question

Wasn't able to find a proper example of this (or maybe I am simply looking in wrong direction).

Depending on incoming parameter value I need to change WHERE condition for SELECT .

For example, I got parameter @bookType with value 'All' and I need to make something like this:

IF @bookType = 'All'
  SELECT * FROM tBooks
  WHERE BookType != 'Template' AND BookGroup='Library'
ELSE
  SELECT * FROM tBooks
  WHERE BookType = @bookType AND BookStatus=@bookStatus

Seems simple, but I need this IF inside WITH:

WITH Books AS (
  IF...
  ...
), bookIds AS (
  ...
  ...
)

And this is not working because I am starting to receive 'Incorrect syntax near IF' . What exactly I am doing wrong? Or maybe it is possible to hide this IF inside WHERE statement (change where depending on parameter value)?

Answer 1

;
WITH Books AS (

     SELECT * FROM tBooks
        WHERE
            (@BookType = 'All'  AND BookType != 'Template' AND BookGroup='Library')
            OR
            (@BookType <> 'All' AND BookType = @bookType AND BookStatus=@bookStatus)

)