Weakening-type coercions for SQL values

3 files changed, 25 insertions, 2 deletions

diff --git a/lib/ur/basis.urs b/lib/ur/basis.urs
index 9bba1ee1..b9d1f55f 100644
--- a/lib/ur/basis.urs
+++ b/lib/ur/basis.urs
@@ -256,6 +256,11 @@ val foreign_key : mine1 ::: Name -> t ::: Type -> mine ::: {Type} -> munused :::
        -> sql_constraint ([mine1 = t] ++ mine ++ munused) []
 
 con sql_exp :: {{Type}} -> {{Type}} -> {Type} -> Type -> Type
+val sql_exp_weaken : fs ::: {{Type}} -> agg ::: {{Type}} -> exps ::: {Type} -> t ::: Type
+                     -> fs' ::: {{Type}} -> agg' ::: {{Type}} -> exps' ::: {Type}
+                     -> [fs ~ fs'] => [agg ~ agg'] => [exps ~ exps'] =>
+                     sql_exp fs agg exps t
+                     -> sql_exp (fs ++ fs') (agg ++ agg') (exps ++ exps') t
 
 val check : fs ::: {Type}
             -> sql_exp [] [] fs bool
@@ -274,6 +279,12 @@ val sql_subset : keep_drop :: {({Type} * {Type})}
                                      (map (fn fields :: ({Type} * {Type}) => fields.1 ++ fields.2) keep_drop)
                                      (map (fn fields :: ({Type} * {Type}) => fields.1) keep_drop)
 val sql_subset_all : tables :: {{Type}} -> sql_subset tables tables
+val sql_subset_concat : big1 ::: {{Type}} -> little1 ::: {{Type}}
+                        -> big2 ::: {{Type}} -> little2 ::: {{Type}}
+                        -> [big1 ~ big2] => [little1 ~ little2] =>
+    sql_subset big1 little1
+    -> sql_subset big2 little2
+    -> sql_subset (big1 ++ big2) (little1 ++ little2)
 
 con sql_from_items :: {{Type}} -> Type
 
@@ -343,10 +354,10 @@ val sql_relop : tables1 ::: {{Type}}
                 -> sql_relop
                 -> sql_query1 tables1 selectedFields selectedExps
                 -> sql_query1 tables2 selectedFields selectedExps
-                -> sql_query1 selectedFields selectedFields selectedExps
+                -> sql_query1 [] selectedFields selectedExps
 val sql_forget_tables : tables ::: {{Type}} -> selectedFields ::: {{Type}} -> selectedExps ::: {Type}
                         -> sql_query1 tables selectedFields selectedExps
-                        -> sql_query1 selectedFields selectedFields selectedExps
+                        -> sql_query1 [] selectedFields selectedExps
 
 type sql_direction
 val sql_asc : sql_direction
diff --git a/lib/ur/top.ur b/lib/ur/top.ur
index ffdd85bf..8b737179 100644
--- a/lib/ur/top.ur
+++ b/lib/ur/top.ur
@@ -234,6 +234,13 @@ fun queryX' [tables ::: {{Type}}] [exps ::: {Type}] [ctx ::: {Unit}] [inp ::: {T
               return <xml>{acc}{r}</xml>)
           <xml/>
 
+fun hasRows [tables ::: {{Type}}] [exps ::: {Type}]
+            [tables ~ exps]
+            (q : sql_query tables exps) =
+    query q
+          (fn _ _ => return True)
+          False
+
 fun oneOrNoRows [tables ::: {{Type}}] [exps ::: {Type}]
                 [tables ~ exps]
                 (q : sql_query tables exps) =
diff --git a/lib/ur/top.urs b/lib/ur/top.urs
index 2b6248fc..59ffec92 100644
--- a/lib/ur/top.urs
+++ b/lib/ur/top.urs
@@ -139,6 +139,11 @@ val queryX' : tables ::: {{Type}} -> exps ::: {Type} -> ctx ::: {Unit} -> inp ::
                   -> transaction (xml ctx inp []))
               -> transaction (xml ctx inp [])
                        
+val hasRows : tables ::: {{Type}} -> exps ::: {Type}
+              -> [tables ~ exps] =>
+    sql_query tables exps
+    -> transaction bool
+
 val oneOrNoRows : tables ::: {{Type}} -> exps ::: {Type}
                   -> [tables ~ exps] =>
                   sql_query tables exps