How can I implement user-friendly boolean logic in a web form GUI?

Question

Currently I have a web application where a user can use dropdown lists to generate SQL SELECT statements like so:

Column Select Dropdown | Operator Dropdown (= != >

Answer 1

This is difficult to represent even in a WinForms app.

What you need to do is implement the concept of a condition group, which consists of one or more statements, and a conditional operator.

The best implementation of this I've see was from GameSpy server filtering -- I just tried to search to find a screenshot, but I came up empty (does that program still exist?). From what I recall, they did something like this:

(
    Condition 1
) OPERATOR
(
    Condition 2
) OPERATOR
(
    (
        Condition 3
    ) OPERATOR
    (
        Condition 4
    )
)