Help with a simple Query

I am trying to make a single display page for an author's books.

the books page only displays books of a type "type" (novels, non-fiction, etc)

I would like to make it so that it can also show all books if "type" isn't selected. I THOUGHT the string would look like this:

<asp:SqlDataSource ID="SqlDSBooks" runat="server" ConnectionString="<%$ ConnectionStrings:csK2Reader%>" SelectCommand="SELECT * FROM [Books] ( If @.Type <> "" then WHERE ([Type] = @.Type)) ORDER BY [SortDate] DESC">

But it doesn't seem to want to work. I get a "server tag is not well formed" error.

Try this:

SELECT*FROM [Books]WHERE (@.TypeISNULLOR [Type]=@.Type)ORDERBY [SortDate]DESC

|||

Or, for text variables:

SELECT*FROM [Books]WHERE [Type] like IsNull(@.Type,'%')ORDERBY [SortDate]DESC

That is not, by the way, an exact equivalent of the previous poster's query.

This version allows a wildcard search, whereas the other query requires an exact match.

For example, if you were wanting to search for both Novels and Novellas, a value for @.Type of 'Novel%' would get you both types of book in one query.

Numbers and dates don't work this way. :(