Expose sqlstate in the connection and stmt APIs.

bindings/ffi_bindings.ml

@@ -308,6 +308,9 @@ module Functions (F : Ctypes.FOREIGN) = struct
   let mysql_ping = foreign "mysql_ping"
     (mysql @-> returning int)
 
+  let mysql_sqlstate = foreign "mysql_sqlstate"
+    (mysql @-> returning string)
+
   let mysql_stmt_prepare = foreign "mysql_stmt_prepare"
     (stmt @-> ptr char @-> ulong @-> returning int)
 
@@ -320,6 +323,9 @@ module Functions (F : Ctypes.FOREIGN) = struct
   let mysql_stmt_fetch = foreign "mysql_stmt_fetch"
     (stmt @-> returning int)
 
+  let mysql_stmt_sqlstate = foreign "mysql_stmt_sqlstate"
+    (stmt @-> returning string)
+
   let mysql_stmt_close = foreign "mysql_stmt_close"
     (stmt @-> returning my_bool)
 

examples/blocking/blocking_example.ml

@@ -47,6 +47,37 @@ let stream res =
     | Error e -> raise (F.E e) in
   next
 
+let test_sqlstate mariadb =
+  assert (M.sqlstate mariadb = "00000");
+  (match M.prepare mariadb "SELECT * FROM inexistent_table" with
+   | Error _ -> assert (M.sqlstate mariadb <> "00000") (* actually "42S02" *)
+   | Ok _ -> assert false);
+  begin
+    let stmt =
+      M.prepare mariadb
+                "CREATE TEMPORARY TABLE test_sqlstate (i integer PRIMARY KEY)"
+        |> or_die "prepare CREATE TABLE test_sqlstate"
+    in
+    let _ =
+      M.Stmt.execute stmt [||]
+        |> or_die "exec CREATE TABLE test_sqlstate"
+    in
+    M.Stmt.close stmt |> or_die "stmt close CREATE TABLE test_sqlstate"
+  end;
+  for i = 0 to 1 do
+    let stmt =
+      M.prepare mariadb "INSERT INTO test_sqlstate VALUES (?)"
+        |> or_die "prepare in test_sqlstate"
+    in
+    (match M.Stmt.execute stmt [|`Int 1|] with
+     | Error (_, _) ->
+        assert (i = 1);
+        assert (M.Stmt.sqlstate stmt <> "00000") (* actually "23000" *)
+     | Ok _ -> assert (i = 0));
+
+    M.Stmt.close stmt |> or_die "stmt close in test_sqlstate"
+  done
+
 let main () =
   let mariadb = connect () |> or_die "connect" in
   let query = env "OCAML_MARIADB_QUERY"
@@ -58,6 +89,7 @@ let main () =
   let s = stream res in
   Seq.iter print_row s;
   M.Stmt.close stmt |> or_die "stmt close";
+  test_sqlstate mariadb;
   M.close mariadb;
   M.library_end ();
   printf "done\n%!"

lib/blocking.ml

@@ -153,6 +153,8 @@ let prepare mariadb query =
 let start_txn mariadb =
   wrap_unit mariadb (B.mysql_real_query mariadb.Common.raw "START TRANSACTION")
 
+let sqlstate = Common.sqlstate
+
 module Res = struct
   type t = [`Blocking] Common.Res.t
 
@@ -203,6 +205,8 @@ module Stmt = struct
     else
       Error (Common.Stmt.error stmt)
 
+  let sqlstate = Common.Stmt.sqlstate
+
   let close stmt =
     Common.Stmt.free_meta stmt;
     let raw = stmt.Common.Stmt.raw in

lib/common.ml

@@ -85,6 +85,9 @@ type error = int * string
 let error mariadb =
   (B.mysql_errno mariadb.raw, B.mysql_error mariadb.raw)
 
+let sqlstate mariadb =
+  B.mysql_sqlstate mariadb.raw
+
 let int_of_server_option = function
   | Multi_statements true -> T.Server_options.multi_statements_on
   | Multi_statements false -> T.Server_options.multi_statements_off
@@ -283,6 +286,9 @@ module Stmt = struct
   let error stmt =
     (B.mysql_stmt_errno stmt.raw, B.mysql_stmt_error stmt.raw)
 
+  let sqlstate stmt =
+    B.mysql_stmt_sqlstate stmt.raw
+
   let fetch_field res i =
     coerce (ptr void) (ptr T.Field.t) (B.mysql_fetch_field_direct res i)
 

lib/mariadb.ml

@@ -80,6 +80,7 @@ module type S = sig
 
     val execute : t -> Field.value array -> Res.t result
     val reset : t -> unit result
+    val sqlstate : t -> string
     val close : t -> unit result
   end
 
@@ -164,6 +165,7 @@ module type S = sig
   val commit : t -> unit result
   val rollback : t -> unit result
   val prepare : t -> string -> Stmt.t result
+  val sqlstate : t -> string
 end
 
 module B = Binding_wrappers

lib/mariadb.mli

@@ -160,6 +160,12 @@ module type S = sig
           were after [stmt] was prepared, and frees up any {!Res.t} produced by
           [stmt]. *)
 
+    val sqlstate : t -> string
+      (** [sqlstate stmt] is the SQLSTATE with MariaDB extensions indicating the
+          status of the previous execution of the statement. The string
+          ["00000"] is returned if no error occurred or if the statement has not
+          been executed. *)
+
     val close : t -> unit result
       (** [close stmt] closes the prepapred statement [stmt] and frees any
           allocated memory associated with it and its result. *)
@@ -282,6 +288,10 @@ module type S = sig
     (** [prepare mariadb query] creates a prepared statement for [query].  The
         query may contain [?] as placeholders for parameters that can be bound
         by calling [Stmt.execute]. *)
+
+  val sqlstate : t -> string
+    (* [sqlstate mariadb] is the SQLSTATE with MariaDB extensions of the last
+     * operation on [mariadb]. Returns ["00000"] if no error occurred. *)
 end
 
 (** The module for blocking MariaDB API calls. It should be possible to call

lib/nonblocking.ml

@@ -218,6 +218,8 @@ let prepare mariadb query =
       `Ok (prepare_start mariadb stmt, prepare_cont mariadb stmt)
   | None -> `Error (Common.error mariadb)
 
+let sqlstate = Common.sqlstate
+
 module Res = struct
   type t = [`Nonblocking] Common.Res.t
 
@@ -354,6 +356,8 @@ module Stmt = struct
 
   let next_result_cont stmt status =
     handle_next stmt (B.mysql_stmt_next_result_cont stmt.Common.Stmt.raw status)
+
+  let sqlstate = Common.Stmt.sqlstate
 end
 
 module type Wait = sig