[Ur] SQL Count

[Adam Chlipala]

David Snider wrote:
> fun isValid r =
>     oneRow (SELECT COUNT(*) FROM users
>                 WHERE Username = {[r.Username]}
>                   AND Password = {[r.Password]}) = 1
>
> It seems to be treating COUNT(*) as a comment. How do I get a record 
> count?

Just include spaces before and after the asterisk.  There are also a few 
other problems here:

- You'll need to include an [AS] name for the expression column you're 
creating.  Every [SELECT]ed column that isn't a projection of a column 
from a table must have an [AS] name in Ur/Web.
- [oneRow] will never return an integer.  You probably want [oneRowE1].
- The result of a query can never be used as a direct operand to the 
equality operator.  This is because query operations must live inside 
the [transaction] monad.  If you're not familiar with the basic 
techniques of monadic programming, I'd recommend finding a tutorial on 
monads in Haskell.