From 36603eae600143253959ad94cdc5bb75a766b91c Mon Sep 17 00:00:00 2001
From: Adam Chlipala <adam@chlipala.net>
Date: Sat, 4 Feb 2012 10:42:18 -0500
Subject: Extend and document RANDOM

---
 doc/manual.tex | 6 ++++--
 src/urweb.grm  | 1 +
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/doc/manual.tex b/doc/manual.tex
index 2097f71a..b1052c36 100644
--- a/doc/manual.tex
+++ b/doc/manual.tex
@@ -1848,6 +1848,7 @@ $$\begin{array}{l}
   \mt{val} \; \mt{sql\_order\_by\_Nil} : \mt{tables} ::: \{\{\mt{Type}\}\} \to \mt{exps} :: \{\mt{Type}\} \to \mt{sql\_order\_by} \; \mt{tables} \; \mt{exps} \\
   \mt{val} \; \mt{sql\_order\_by\_Cons} : \mt{tables} ::: \{\{\mt{Type}\}\} \to \mt{exps} ::: \{\mt{Type}\} \to \mt{t} ::: \mt{Type} \\
   \hspace{.1in} \to \mt{sql\_exp} \; \mt{tables} \; [] \; \mt{exps} \; \mt{t} \to \mt{sql\_direction} \to \mt{sql\_order\_by} \; \mt{tables} \; \mt{exps} \to \mt{sql\_order\_by} \; \mt{tables} \; \mt{exps} \\
+  \mt{val} \; \mt{sql\_order\_by\_random} : \mt{tables} ::: \{\{\mt{Type}\}\} \to \mt{exps} ::: \{\mt{Type}\} \to \mt{sql\_order\_by} \; \mt{tables} \; \mt{exps} \\
   \\
   \mt{type} \; \mt{sql\_limit} \\
   \mt{val} \; \mt{sql\_no\_limit} : \mt{sql\_limit} \\
@@ -2125,10 +2126,11 @@ A signature item $\mt{table} \; \mt{x} : \mt{c}$ is actually elaborated into two
 Queries $Q$ are added to the rules for expressions $e$.
 
 $$\begin{array}{rrcll}
-  \textrm{Queries} & Q &::=& (q \; [\mt{ORDER} \; \mt{BY} \; (E \; [o],)^+] \; [\mt{LIMIT} \; N] \; [\mt{OFFSET} \; N]) \\
+  \textrm{Queries} & Q &::=& (q \; [\mt{ORDER} \; \mt{BY} \; O] \; [\mt{LIMIT} \; N] \; [\mt{OFFSET} \; N]) \\
   \textrm{Pre-queries} & q &::=& \mt{SELECT} \; [\mt{DISTINCT}] \; P \; \mt{FROM} \; F,^+ \; [\mt{WHERE} \; E] \; [\mt{GROUP} \; \mt{BY} \; p,^+] \; [\mt{HAVING} \; E] \\
   &&& \mid q \; R \; q \mid \{\{\{e\}\}\} \\
-  \textrm{Relational operators} & R &::=& \mt{UNION} \mid \mt{INTERSECT} \mid \mt{EXCEPT}
+  \textrm{Relational operators} & R &::=& \mt{UNION} \mid \mt{INTERSECT} \mid \mt{EXCEPT} \\
+  \textrm{$\mt{ORDER \; BY}$ items} & O &::=& \mt{RANDOM} [()] \mid E \; [o] \mid E \; [o], O
 \end{array}$$
 
 $$\begin{array}{rrcll}
diff --git a/src/urweb.grm b/src/urweb.grm
index 7d2bc96b..80e40bc3 100644
--- a/src/urweb.grm
+++ b/src/urweb.grm
@@ -2039,6 +2039,7 @@ obexps : obitem                         (let
 
 popt   :                                ()
        | LPAREN RPAREN                  ()
+       | UNIT                           ()
 
 diropt :                                (EVar (["Basis"], "sql_asc", Infer), dummy)
        | ASC                            (EVar (["Basis"], "sql_asc", Infer), s (ASCleft, ASCright))
-- 
cgit v1.2.3