Ur/Web: tests/group_by.ur annotate

Avoid unnecessary WHERE clause

author	Adam Chlipala <adamc@hcoop.net>
date	Sun, 31 Aug 2008 15:32:31 -0400
parents	69d337f186eb
children	d1b679dbbc25

rev	line source
adamc@226	1 table t1 : {A : int, B : string, C : float}
adamc@226	2 table t2 : {A : float, D : int}
adamc@226	3
adamc@226	4 val q1 = (SELECT * FROM t1 GROUP BY t1.B)
adamc@226	5 val q2 = (SELECT * FROM t1, t2 GROUP BY t1.B, t2.D, t1.A)
adamc@227	6
adamc@227	7 val q3 = (SELECT * FROM t1 WHERE t1.A = 0 GROUP BY t1.B)
adamc@227	8 val q4 = (SELECT * FROM t1 WHERE t1.A = 0 GROUP BY t1.C HAVING t1.C < 0.2)
adamc@227	9
adamc@227	10 val q5 = (SELECT t1.A, t2.D FROM t1, t2 GROUP BY t2.D, t1.A)
adamc@228	11 val q6 = (SELECT t1.A, t2.D FROM t1, t2 WHERE t1.C = 0.0 GROUP BY t2.D, t1.A HAVING t1.A = t1.A AND t2.D = 17)
adamc@255	12
adamc@255	13
adamc@255	14 datatype list a = Nil \| Cons of a * list a
adamc@255	15
adamc@255	16 val r1 : transaction (list {B : string}) =
adamc@255	17 query q1
adamc@255	18 (fn fs acc => return (Cons (fs.T1, acc)))
adamc@255	19 Nil
adamc@255	20
adamc@255	21 val r2 : transaction string =
adamc@255	22 ls <- r1;
adamc@255	23 return (case ls of
adamc@255	24 Nil => "Problem"
adamc@255	25 \| Cons ({B = b, ...}, _) => b)
adamc@255	26
adamc@255	27 val main : unit -> transaction page = fn () =>
adamc@255	28 s <- r2;
adamc@255	29 return <html><body>
adamc@255	30 {cdata s}
adamc@255	31 </body></html>

Mercurial > urweb