MySQL query gets up to C linking

6 files changed, 547 insertions, 27 deletions

diff --git a/doc/manual.tex b/doc/manual.tex
index 22c219ad..3b57dc1b 100644
--- a/doc/manual.tex
+++ b/doc/manual.tex
@@ -137,6 +137,7 @@ Here is the complete list of directive forms.  ``FFI'' stands for ``foreign func
 \item \texttt{effectful Module.ident} registers an FFI function or transaction as having side effects.  The optimizer avoids removing, moving, or duplicating calls to such functions.  Every effectful FFI function must be registered, or the optimizer may make invalid transformations.
 \item \texttt{exe FILENAME} sets the filename to which to write the output executable.  The default for file \texttt{P.urp} is \texttt{P.exe}.  
 \item \texttt{ffi FILENAME} reads the file \texttt{FILENAME.urs} to determine the interface to a new FFI module.  The name of the module is calculated from \texttt{FILENAME} in the same way as for normal source files.  See the files \texttt{include/urweb.h} and \texttt{src/c/urweb.c} for examples of C headers and implementations for FFI modules.  In general, every type or value \texttt{Module.ident} becomes \texttt{uw\_Module\_ident} in C.
+\item \texttt{header FILENAME} adds \texttt{FILENAME} to the list of files to be \texttt{\#include}d in C sources.  This is most useful for interfacing with new FFI modules.
 \item \texttt{jsFunc Module.ident=name} gives the JavaScript name of an FFI value.
 \item \texttt{library FILENAME} parses \texttt{FILENAME.urp} and merges its contents with the rest of the current file's contents.
 \item \texttt{link FILENAME} adds \texttt{FILENAME} to the list of files to be passed to the GCC linker at the end of compilation.  This is most useful for importing extra libraries needed by new FFI modules.
@@ -193,7 +194,7 @@ We give the Ur language definition in \LaTeX $\;$ math mode, since that is prett
 
 We often write syntax like $e^*$ to indicate zero or more copies of $e$, $e^+$ to indicate one or more copies, and $e,^*$ and $e,^+$ to indicate multiple copies separated by commas.  Another separator may be used in place of a comma.  The $e$ term may be surrounded by parentheses to indicate grouping; those parentheses should not be included in the actual ASCII.
 
-We write $\ell$ for literals of the primitive types, for the most part following C conventions.  There are $\mt{int}$, $\mt{float}$, and $\mt{string}$ literals.
+We write $\ell$ for literals of the primitive types, for the most part following C conventions.  There are $\mt{int}$, $\mt{float}$, $\mt{char}$, and $\mt{string}$ literals.  Character literals follow the SML convention instead of the C convention, written like \texttt{\#"a"} instead of \texttt{'a'}.
 
 This version of the manual doesn't include operator precedences; see \texttt{src/urweb.grm} for that.
 
@@ -610,7 +611,7 @@ $$\infer{\Gamma \vdash \mt{map} \; f \; (c_1 \rc c_2) \equiv \mt{map} \; f \; c_
 
 \subsection{Expression Typing}
 
-We assume the existence of a function $T$ assigning types to literal constants.  It maps integer constants to $\mt{Basis}.\mt{int}$, float constants to $\mt{Basis}.\mt{float}$, and string constants to $\mt{Basis}.\mt{string}$.
+We assume the existence of a function $T$ assigning types to literal constants.  It maps integer constants to $\mt{Basis}.\mt{int}$, float constants to $\mt{Basis}.\mt{float}$, character constants to $\mt{Basis}.\mt{char}$, and string constants to $\mt{Basis}.\mt{string}$.
 
 We also refer to a function $\mathcal I$, such that $\mathcal I(\tau)$ ``uses an oracle'' to instantiate all constructor function arguments at the beginning of $\tau$ that are marked implicit; i.e., replace $x_1 ::: \kappa_1 \to \ldots \to x_n ::: \kappa_n \to \tau$ with $[x_1 \mapsto c_1]\ldots[x_n \mapsto c_n]\tau$, where the $c_i$s are inferred and $\tau$ does not start like $x ::: \kappa \to \tau'$.
 
@@ -1147,6 +1148,7 @@ The idea behind Ur is to serve as the ideal host for embedded domain-specific la
 $$\begin{array}{l}
   \mt{type} \; \mt{int} \\
   \mt{type} \; \mt{float} \\
+  \mt{type} \; \mt{char} \\
   \mt{type} \; \mt{string} \\
   \mt{type} \; \mt{time} \\
   \mt{type} \; \mt{blob} \\
diff --git a/src/cjr_print.sml b/src/cjr_print.sml
index 7d1120b4..fcfa402e 100644
--- a/src/cjr_print.sml
+++ b/src/cjr_print.sml
@@ -1652,7 +1652,7 @@ fun p_exp' par env (e, loc) =
 
                           #query (Settings.currentDbms ())
                                  {loc = loc,
-                                  numCols = length outputs,
+                                  cols = map (fn (_, t) => sql_type_in env t) outputs,
                                   doCols = doCols}]
                    | SOME (id, query) =>
                      box [p_list_sepi newline
@@ -1675,7 +1675,7 @@ fun p_exp' par env (e, loc) =
                                           id = id,
                                           query = query,
                                           inputs = map #2 inputs,
-                                          numCols = length outputs,
+                                          cols = map (fn (_, t) => sql_type_in env t) outputs,
                                           doCols = doCols}],
                  newline,
 
@@ -2797,7 +2797,8 @@ fun p_sql env (ds, _) =
                                                             box [string "uw_",
                                                                  string (CharVector.map Char.toLower x),
                                                                  space,
-                                                                 p_sqltype env (t, ErrorMsg.dummySpan)]) xts,
+                                                                 string (#p_sql_type (Settings.currentDbms ())
+                                                                                     (sql_type_in env t))]) xts,
                                                  case (pk, csts) of
                                                      ("", []) => box []
                                                    | _ => string ",",
diff --git a/src/mysql.sml b/src/mysql.sml
index 7b02c787..2fcdef2d 100644
--- a/src/mysql.sml
+++ b/src/mysql.sml
@@ -31,6 +31,30 @@ open Settings
 open Print.PD
 open Print
 
+fun p_sql_type t =
+    case t of
+        Int => "bigint"
+      | Float => "double"
+      | String => "longtext"
+      | Bool => "bool"
+      | Time => "timestamp"
+      | Blob => "longblob"
+      | Channel => "bigint"
+      | Client => "int"
+      | Nullable t => p_sql_type t
+
+fun p_buffer_type t =
+    case t of
+        Int => "MYSQL_TYPE_LONGLONG"
+      | Float => "MYSQL_TYPE_DOUBLE"
+      | String => "MYSQL_TYPE_STRING"
+      | Bool => "MYSQL_TYPE_LONG"
+      | Time => "MYSQL_TYPE_TIME"
+      | Blob => "MYSQL_TYPE_BLOB"
+      | Channel => "MYSQL_TYPE_LONGLONG"
+      | Client => "MYSQL_TYPE_LONG"
+      | Nullable t => p_buffer_type t
+
 fun init {dbstring, prepared = ss, tables, views, sequences} =
     let
         val host = ref NONE
@@ -138,6 +162,10 @@ fun init {dbstring, prepared = ss, tables, views, sequences} =
                                                                     newline,
                                                                     uhoh true "Error preparing statement: %s" ["msg"]],
                                                                string "}",
+                                                               newline,
+                                                               string "conn->p",
+                                                               string (Int.toString i),
+                                                               string " = stmt;",
                                                                newline]
                                                       end)
                                   ss,
@@ -253,12 +281,484 @@ fun init {dbstring, prepared = ss, tables, views, sequences} =
              newline]
     end
 
-fun query _ = raise Fail "MySQL query"
-fun queryPrepared _ = raise Fail "MySQL queryPrepared"
-fun dml _ = raise Fail "MySQL dml"
-fun dmlPrepared _ = raise Fail "MySQL dmlPrepared"
-fun nextval _ = raise Fail "MySQL nextval"
-fun nextvalPrepared _ = raise Fail "MySQL nextvalPrepared"
+fun p_getcol {wontLeakStrings = _, col = i, typ = t} =
+    let
+        fun getter t =
+            case t of
+                String => box [string "({",
+                               newline,
+                               string "uw_Basis_string s = uw_malloc(ctx, length",
+                               string (Int.toString i),
+                               string " + 1);",
+                               newline,
+                               string "out[",
+                               string (Int.toString i),
+                               string "].buffer = s;",
+                               newline,
+                               string "out[",
+                               string (Int.toString i),
+                               string "].buffer_length = length",
+                               string (Int.toString i),
+                               string " + 1;",
+                               newline,
+                               string "mysql_stmt_fetch_column(stmt, &out[",
+                               string (Int.toString i),
+                               string "], ",
+                               string (Int.toString i),
+                               string ", 0);",
+                               newline,
+                               string "s[length",
+                               string (Int.toString i),
+                               string "] = 0;",
+                               newline,
+                               string "s;",
+                               newline,
+                               string "})"]
+              | Blob => box [string "({",
+                             newline,
+                             string "uw_Basis_blob b = {length",
+                             string (Int.toString i),
+                             string ", uw_malloc(ctx, length",
+                             string (Int.toString i),
+                             string ")};",
+                             newline,
+                             string "out[",
+                             string (Int.toString i),
+                             string "].buffer = b.data;",
+                             newline,
+                             string "out[",
+                             string (Int.toString i),
+                             string "].buffer_length = length",
+                             string (Int.toString i),
+                             string ";",
+                             newline,
+                             string "mysql_stmt_fetch_column(stmt, &out[",
+                             string (Int.toString i),
+                             string "], ",
+                             string (Int.toString i),
+                             string ", 0);",
+                             newline,
+                             string "b;",
+                             newline,
+                             string "})"]
+              | Time => box [string "({",
+                             string "MYSQL_TIME *mt = buffer",
+                             string (Int.toString i),
+                             string ";",
+                             newline,
+                             newline,
+                             string "struct tm t = {mt->second, mt->minute, mt->hour, mt->day, mt->month, mt->year, 0, 0, -1};",
+                             newline,
+                             string "mktime(&tm);",
+                             newline,
+                             string "})"]
+              | _ => box [string "buffer",
+                          string (Int.toString i)]
+    in
+        case t of
+            Nullable t => box [string "(is_null",
+                               string (Int.toString i),
+                               string " ? NULL : ",
+                               case t of
+                                   String => getter t
+                                 | _ => box [string "({",
+                                             newline,
+                                             string (p_sql_ctype t),
+                                             space,
+                                             string "*tmp = uw_malloc(ctx, sizeof(",
+                                             string (p_sql_ctype t),
+                                             string "));",
+                                             newline,
+                                             string "*tmp = ",
+                                             getter t,
+                                             string ";",
+                                             newline,
+                                             string "tmp;",
+                                             newline,
+                                             string "})"],
+                               string ")"]
+          | _ => box [string "(is_null",
+                      string (Int.toString i),
+                      string " ? ",
+                      box [string "({",
+                           string (p_sql_ctype t),
+                           space,
+                           string "tmp;",
+                           newline,
+                           string "uw_error(ctx, FATAL, \"Unexpectedly NULL field #",
+                           string (Int.toString i),
+                           string "\");",
+                           newline,
+                           string "tmp;",
+                           newline,
+                           string "})"],
+                      string " : ",
+                      getter t,
+                      string ")"]
+    end
+
+fun queryCommon {loc, query, cols, doCols} =
+    box [string "int n, r;",
+         newline,
+         string "MYSQL_BIND out[",
+         string (Int.toString (length cols)),
+         string "];",
+         newline,
+         p_list_sepi (box []) (fn i => fn t =>
+                                          let
+                                              fun buffers t =
+                                                  case t of
+                                                      String => box [string "unsigned long length",
+                                                                     string (Int.toString i),
+                                                                     string ";",
+                                                                     newline]
+                                                    | Blob => box [string "unsigned long length",
+                                                                   string (Int.toString i),
+                                                                   string ";",
+                                                                   newline]
+                                                    | _ => box [string (p_sql_ctype t),
+                                                                space,
+                                                                string "buffer",
+                                                                string (Int.toString i),
+                                                                string ";",
+                                                                newline]
+                                          in
+                                              box [string "my_bool is_null",
+                                                   string (Int.toString i),
+                                                   string ";",
+                                                   newline,
+                                                   case t of
+                                                       Nullable t => buffers t
+                                                     | _ => buffers t,
+                                                   newline]
+                                          end) cols,
+         newline,
+
+         string "memset(out, 0, sizeof out);",
+         newline,
+         p_list_sepi (box []) (fn i => fn t =>
+                                          let
+                                              fun buffers t =
+                                                  case t of
+                                                      String => box []
+                                                    | Blob => box []
+                                                    | _ => box [string "out[",
+                                                                string (Int.toString i),
+                                                                string "].buffer = &buffer",
+                                                                string (Int.toString i),
+                                                                string ";",
+                                                                newline]
+                                          in
+                                              box [string "out[",
+                                                   string (Int.toString i),
+                                                   string "].buffer_type = ",
+                                                   string (p_buffer_type t),
+                                                   string ";",
+                                                   newline,
+                                                   string "out[",
+                                                   string (Int.toString i),
+                                                   string "].is_null = &is_null",
+                                                   string (Int.toString i),
+                                                   string ";",
+                                                   newline,
+                                                               
+                                                   case t of
+                                                       Nullable t => buffers t
+                                                     | _ => buffers t,
+                                                  newline]
+                                          end) cols,
+         newline,
+
+         string "if (mysql_stmt_execute(stmt)) uw_error(ctx, FATAL, \"",
+         string (ErrorMsg.spanToString loc),
+         string ": Error executing query\");",
+         newline,
+         newline,
+
+         string "if (mysql_stmt_store_result(stmt)) uw_error(ctx, FATAL, \"",
+         string (ErrorMsg.spanToString loc),
+         string ": Error storing query result\");",
+         newline,
+         newline,
+
+         string "if (mysql_stmt_bind_result(stmt, out)) uw_error(ctx, FATAL, \"",
+         string (ErrorMsg.spanToString loc),
+         string ": Error binding query result\");",
+         newline,
+         newline,
+
+         string "uw_end_region(ctx);",
+         newline,
+         string "while ((r = mysql_stmt_fetch(stmt)) == 0) {",
+         newline,
+         doCols p_getcol,
+         string "}",
+         newline,
+         newline,
+
+         string "if (r != MYSQL_NO_DATA) uw_error(ctx, FATAL, \"",
+         string (ErrorMsg.spanToString loc),
+         string ": query result fetching failed\");",
+         newline]    
+
+fun query {loc, cols, doCols} =
+    box [string "uw_conn *conn = uw_get_db(ctx);",
+         newline,
+         string "MYSQL_stmt *stmt = mysql_stmt_init(conn->conn);",
+         newline,
+         string "if (stmt == NULL) uw_error(ctx, \"",
+         string (ErrorMsg.spanToString loc),
+         string ": can't allocate temporary prepared statement\");",
+         newline,
+         string "uw_push_cleanup(ctx, (void (*)(void *))mysql_stmt_close, stmt);",
+         newline,
+         string "if (mysql_stmt_prepare(stmt, query, strlen(query))) uw_error(ctx, FATAL, \"",
+         string (ErrorMsg.spanToString loc),
+         string "\");",
+         newline,
+         newline,
+
+         p_list_sepi (box []) (fn i => fn t =>
+                                          let
+                                              fun buffers t =
+                                                  case t of
+                                                      String => box []
+                                                    | Blob => box []
+                                                    | _ => box [string "out[",
+                                                                string (Int.toString i),
+                                                                string "].buffer = &buffer",
+                                                                string (Int.toString i),
+                                                                string ";",
+                                                                newline]
+                                          in
+                                              box [string "in[",
+                                                   string (Int.toString i),
+                                                   string "].buffer_type = ",
+                                                   string (p_buffer_type t),
+                                                   string ";",
+                                                   newline,
+                                                               
+                                                   case t of
+                                                       Nullable t => box [string "in[",
+                                                                          string (Int.toString i),
+                                                                          string "].is_null = &is_null",
+                                                                          string (Int.toString i),
+                                                                          string ";",
+                                                                          newline,
+                                                                          buffers t]
+                                                     | _ => buffers t,
+                                                  newline]
+                                          end) cols,
+         newline,
+
+         queryCommon {loc = loc, cols = cols, doCols = doCols, query = string "query"},
+
+         string "uw_pop_cleanup(ctx);",
+         newline]
+
+fun p_ensql t e =
+    case t of
+        Int => box [string "uw_Basis_attrifyInt(ctx, ", e, string ")"]
+      | Float => box [string "uw_Basis_attrifyFloat(ctx, ", e, string ")"]
+      | String => e
+      | Bool => box [string "(", e, string " ? \"TRUE\" : \"FALSE\")"]
+      | Time => box [string "uw_Basis_attrifyTime(ctx, ", e, string ")"]
+      | Blob => box [e, string ".data"]
+      | Channel => box [string "uw_Basis_attrifyChannel(ctx, ", e, string ")"]
+      | Client => box [string "uw_Basis_attrifyClient(ctx, ", e, string ")"]
+      | Nullable String => e
+      | Nullable t => box [string "(",
+                           e,
+                           string " == NULL ? NULL : ",
+                           p_ensql t (box [string "(*", e, string ")"]),
+                           string ")"]
+
+fun queryPrepared {loc, id, query, inputs, cols, doCols} =
+    box [string "uw_conn *conn = uw_get_db(ctx);",
+         newline,
+         string "MYSQL_BIND in[",
+         string (Int.toString (length inputs)),
+         string "];",
+         newline,
+         p_list_sepi (box []) (fn i => fn t =>
+                                          let
+                                              fun buffers t =
+                                                  case t of
+                                                      String => box [string "unsigned long in_length",
+                                                                     string (Int.toString i),
+                                                                     string ";",
+                                                                     newline]
+                                                    | Blob => box [string "unsigned long in_length",
+                                                                   string (Int.toString i),
+                                                                   string ";",
+                                                                   newline]
+                                                    | Time => box [string (p_sql_ctype t),
+                                                                   space,
+                                                                   string "in_buffer",
+                                                                   string (Int.toString i),
+                                                                   string ";",
+                                                                   newline]
+                                                    | _ => box []
+                                          in
+                                              box [case t of
+                                                       Nullable t => box [string "my_bool in_is_null",
+                                                                          string (Int.toString i),
+                                                                          string ";",
+                                                                          newline,
+                                                                          buffers t]
+                                                     | _ => buffers t,
+                                                   newline]
+                                          end) inputs,
+         string "MYSQL_STMT *stmt = conn->p",
+         string (Int.toString id),
+         string ";",
+         newline,
+         newline,
+
+         string "memset(in, 0, sizeof in);",
+         newline,
+         p_list_sepi (box []) (fn i => fn t =>
+                                          let
+                                              fun buffers t =
+                                                  case t of
+                                                      String => box [string "in[",
+                                                                     string (Int.toString i),
+                                                                     string "].buffer = arg",
+                                                                     string (Int.toString (i + 1)),
+                                                                     string ";",
+                                                                     newline,
+                                                                     string "in_length",
+                                                                     string (Int.toString i),
+                                                                     string "= in[",
+                                                                     string (Int.toString i),
+                                                                     string "].buffer_length = strlen(arg",
+                                                                     string (Int.toString (i + 1)),
+                                                                     string ");",
+                                                                     newline,
+                                                                     string "in[",
+                                                                     string (Int.toString i),
+                                                                     string "].length = &in_length",
+                                                                     string (Int.toString i),
+                                                                     string ";",
+                                                                     newline]
+                                                    | Blob => box [string "in[",
+                                                                   string (Int.toString i),
+                                                                   string "].buffer = arg",
+                                                                   string (Int.toString (i + 1)),
+                                                                   string ".data;",
+                                                                   newline,
+                                                                   string "in_length",
+                                                                   string (Int.toString i),
+                                                                   string "= in[",
+                                                                   string (Int.toString i),
+                                                                   string "].buffer_length = arg",
+                                                                   string (Int.toString (i + 1)),
+                                                                   string ".size;",
+                                                                   newline,
+                                                                   string "in[",
+                                                                   string (Int.toString i),
+                                                                   string "].length = &in_length",
+                                                                   string (Int.toString i),
+                                                                   string ";",
+                                                                   newline]
+                                                    | Time =>
+                                                      let
+                                                          fun oneField dst src =
+                                                              box [string "in_buffer",
+                                                                   string (Int.toString i),
+                                                                   string ".",
+                                                                   string dst,
+                                                                   string " = tms.tm_",
+                                                                   string src,
+                                                                   string ";",
+                                                                   newline]
+                                                      in
+                                                          box [string "({",
+                                                               newline,
+                                                               string "struct tm tms;",
+                                                               newline,
+                                                               string "if (localtime_r(&arg",
+                                                               string (Int.toString (i + 1)),
+                                                               string ", &tm) == NULL) uw_error(\"",
+                                                               string (ErrorMsg.spanToString loc),
+                                                               string ": error converting to MySQL time\");",
+                                                               newline,
+                                                               oneField "year" "year",
+                                                               oneField "month" "mon",
+                                                               oneField "day" "mday",
+                                                               oneField "hour" "hour",
+                                                               oneField "minute" "min",
+                                                               oneField "second" "sec",
+                                                               newline,
+                                                               string "in[",
+                                                               string (Int.toString i),
+                                                               string "].buffer = &in_buffer",
+                                                               string (Int.toString i),
+                                                               string ";",
+                                                               newline]
+                                                      end
+                                                                   
+                                                    | _ => box [string "in[",
+                                                                string (Int.toString i),
+                                                                string "].buffer = &arg",
+                                                                string (Int.toString (i + 1)),
+                                                                string ";",
+                                                                newline]
+                                          in
+                                              box [string "in[",
+                                                   string (Int.toString i),
+                                                   string "].buffer_type = ",
+                                                   string (p_buffer_type t),
+                                                   string ";",
+                                                   newline,
+                                                               
+                                                   case t of
+                                                       Nullable t => box [string "in[",
+                                                                          string (Int.toString i),
+                                                                          string "].is_null = &in_is_null",
+                                                                          string (Int.toString i),
+                                                                          string ";",
+                                                                          newline,
+                                                                          string "if (arg",
+                                                                          string (Int.toString (i + 1)),
+                                                                          string " == NULL) {",
+                                                                          newline,
+                                                                          box [string "in_is_null",
+                                                                               string (Int.toString i),
+                                                                               string " = 1;",
+                                                                               newline],
+                                                                          string "} else {",
+                                                                          box [case t of
+                                                                                   String => box []
+                                                                                 | _ =>
+                                                                                   box [string (p_sql_ctype t),
+                                                                                        space,
+                                                                                        string "arg",
+                                                                                        string (Int.toString (i + 1)),
+                                                                                        string " = *arg",
+                                                                                        string (Int.toString (i + 1)),
+                                                                                        string ";",
+                                                                                        newline],
+                                                                               string "in_is_null",
+                                                                               string (Int.toString i),
+                                                                               string " = 0;",
+                                                                               newline,
+                                                                               buffers t,
+                                                                               newline]]
+                                                                          
+                                                     | _ => buffers t,
+                                                   newline]
+                                          end) inputs,
+         newline,
+
+         queryCommon {loc = loc, cols = cols, doCols = doCols, query = box [string "\"",
+                                                                            string (String.toString query),
+                                                                            string "\""]}]
+
+fun dml _ = box []
+fun dmlPrepared _ = box []
+fun nextval _ = box []
+fun nextvalPrepared _ = box []
 
 val () = addDbms {name = "mysql",
                   header = "mysql/mysql.h",
@@ -276,6 +776,7 @@ val () = addDbms {name = "mysql",
                               string "}",
                                      newline],
                   init = init,
+                  p_sql_type = p_sql_type,
                   query = query,
                   queryPrepared = queryPrepared,
                   dml = dml,
diff --git a/src/postgres.sml b/src/postgres.sml
index 07a68607..ca71798f 100644
--- a/src/postgres.sml
+++ b/src/postgres.sml
@@ -34,6 +34,18 @@ open Print
 val ident = String.translate (fn #"'" => "PRIME"
                                | ch => str ch)
 
+fun p_sql_type t =
+    case t of
+        Int => "int8"
+      | Float => "float8"
+      | String => "text"
+      | Bool => "bool"
+      | Time => "timestamp"
+      | Blob => "bytea"
+      | Channel => "int8"
+      | Client => "int4"
+      | Nullable t => p_sql_type t
+
 fun p_sql_type_base t =
     case t of
         Int => "bigint"
@@ -540,7 +552,7 @@ fun p_getcol {wontLeakStrings, col = i, typ = t} =
         getter t
     end
 
-fun queryCommon {loc, query, numCols, doCols} =
+fun queryCommon {loc, query, cols, doCols} =
     box [string "int n, i;",
          newline,
          newline,
@@ -564,7 +576,7 @@ fun queryCommon {loc, query, numCols, doCols} =
          newline,
 
          string "if (PQnfields(res) != ",
-         string (Int.toString numCols),
+         string (Int.toString (length cols)),
          string ") {",
          newline,
          box [string "int nf = PQnfields(res);",
@@ -574,7 +586,7 @@ fun queryCommon {loc, query, numCols, doCols} =
               string "uw_error(ctx, FATAL, \"",
               string (ErrorMsg.spanToString loc),
               string ": Query returned %d columns instead of ",
-              string (Int.toString numCols),
+              string (Int.toString (length cols)),
               string ":\\n%s\\n%s\", nf, ",
               query,
               string ", PQerrorMessage(conn));",
@@ -598,13 +610,13 @@ fun queryCommon {loc, query, numCols, doCols} =
          string "uw_pop_cleanup(ctx);",
          newline]    
 
-fun query {loc, numCols, doCols} =
+fun query {loc, cols, doCols} =
     box [string "PGconn *conn = uw_get_db(ctx);",
          newline,
          string "PGresult *res = PQexecParams(conn, query, 0, NULL, NULL, NULL, NULL, 0);",
          newline,
          newline,
-         queryCommon {loc = loc, numCols = numCols, doCols = doCols, query = string "query"}]
+         queryCommon {loc = loc, cols = cols, doCols = doCols, query = string "query"}]
 
 fun p_ensql t e =
     case t of
@@ -623,7 +635,7 @@ fun p_ensql t e =
                            p_ensql t (box [string "(*", e, string ")"]),
                            string ")"]
 
-fun queryPrepared {loc, id, query, inputs, numCols, doCols} =
+fun queryPrepared {loc, id, query, inputs, cols, doCols} =
     box [string "PGconn *conn = uw_get_db(ctx);",
          newline,
          string "const int paramFormats[] = { ",
@@ -662,9 +674,9 @@ fun queryPrepared {loc, id, query, inputs, numCols, doCols} =
                   string ", NULL, paramValues, paramLengths, paramFormats, 0);"],
          newline,
          newline,
-         queryCommon {loc = loc, numCols = numCols, doCols = doCols, query = box [string "\"",
-                                                                                  string (String.toString query),
-                                                                                  string "\""]}]
+         queryCommon {loc = loc, cols = cols, doCols = doCols, query = box [string "\"",
+                                                                            string (String.toString query),
+                                                                            string "\""]}]
 
 fun dmlCommon {loc, dml} =
     box [string "if (res == NULL) uw_error(ctx, FATAL, \"Out of memory allocating DML result.\");",
@@ -821,6 +833,7 @@ val () = addDbms {name = "postgres",
                   link = "-lpq",
                   global_init = box [string "void uw_client_init() { }",
                                      newline],
+                  p_sql_type = p_sql_type,
                   init = init,
                   query = query,
                   queryPrepared = queryPrepared,
diff --git a/src/settings.sig b/src/settings.sig
index 5406d1de..14e6338d 100644
--- a/src/settings.sig
+++ b/src/settings.sig
@@ -112,7 +112,7 @@ signature SETTINGS = sig
            | Client
            | Nullable of sql_type
 
-    val p_sql_type : sql_type -> string
+    val p_sql_ctype : sql_type -> string
     val isBlob : sql_type -> bool
     val isNotNull : sql_type -> bool
 
@@ -125,18 +125,19 @@ signature SETTINGS = sig
          (* Pass these linker arguments *)
          global_init : Print.PD.pp_desc,
          (* Define uw_client_init() *)
+         p_sql_type : sql_type -> string,
          init : {dbstring : string,
                  prepared : (string * int) list,
                  tables : (string * (string * sql_type) list) list,
                  views : (string * (string * sql_type) list) list,
                  sequences : string list} -> Print.PD.pp_desc,
          (* Define uw_db_init(), uw_db_close(), uw_db_begin(), uw_db_commit(), and uw_db_rollback() *)
-         query : {loc : ErrorMsg.span, numCols : int,
+         query : {loc : ErrorMsg.span, cols : sql_type list,
                   doCols : ({wontLeakStrings : bool, col : int, typ : sql_type} -> Print.PD.pp_desc)
                            -> Print.PD.pp_desc}
                  -> Print.PD.pp_desc,
          queryPrepared : {loc : ErrorMsg.span, id : int, query : string,
-                          inputs : sql_type list, numCols : int,
+                          inputs : sql_type list, cols : sql_type list,
                           doCols : ({wontLeakStrings : bool, col : int, typ : sql_type} -> Print.PD.pp_desc)
                                    -> Print.PD.pp_desc}
                          -> Print.PD.pp_desc,
diff --git a/src/settings.sml b/src/settings.sml
index a242768f..f2c2461d 100644
--- a/src/settings.sml
+++ b/src/settings.sml
@@ -285,7 +285,7 @@ datatype sql_type =
        | Client
        | Nullable of sql_type
 
-fun p_sql_type t =
+fun p_sql_ctype t =
     let
         open Print.PD
         open Print
@@ -300,7 +300,7 @@ fun p_sql_type t =
           | Channel => "uw_Basis_channel"
           | Client => "uw_Basis_client"
           | Nullable String => "uw_Basis_string"
-          | Nullable t => p_sql_type t ^ "*"
+          | Nullable t => p_sql_ctype t ^ "*"
     end
 
 fun isBlob Blob = true
@@ -315,17 +315,18 @@ type dbms = {
      header : string,
      link : string,
      global_init : Print.PD.pp_desc,
+     p_sql_type : sql_type -> string,
      init : {dbstring : string,
              prepared : (string * int) list,
              tables : (string * (string * sql_type) list) list,
              views : (string * (string * sql_type) list) list,
              sequences : string list} -> Print.PD.pp_desc,
-     query : {loc : ErrorMsg.span, numCols : int,
+     query : {loc : ErrorMsg.span, cols : sql_type list,
               doCols : ({wontLeakStrings : bool, col : int, typ : sql_type} -> Print.PD.pp_desc)
                        -> Print.PD.pp_desc}
              -> Print.PD.pp_desc,
      queryPrepared : {loc : ErrorMsg.span, id : int, query : string,
-                      inputs : sql_type list, numCols : int,
+                      inputs : sql_type list, cols : sql_type list,
                       doCols : ({wontLeakStrings : bool, col : int, typ : sql_type} -> Print.PD.pp_desc)
                                -> Print.PD.pp_desc}
                      -> Print.PD.pp_desc,
@@ -341,6 +342,7 @@ val curDb = ref ({name = "",
                   header = "",
                   link = "",
                   global_init = Print.box [],
+                  p_sql_type = fn _ => "",
                   init = fn _ => Print.box [],
                   query = fn _ => Print.box [],
                   queryPrepared = fn _ => Print.box [],