add mysql_stmt_insert_id binding

bindings/ffi_bindings.ml

@@ -271,6 +271,9 @@ module Bindings (F : Cstubs.FOREIGN) = struct
   let mysql_stmt_affected_rows = foreign "mysql_stmt_affected_rows"
     (stmt @-> returning ullong)
 
+  let mysql_stmt_insert_id = foreign "mysql_stmt_insert_id"
+    (stmt @-> returning ullong)
+
   (* Blocking API *)
 
   let mysql_free_result = foreign "mysql_free_result"

lib/binding_wrappers.ml

@@ -48,6 +48,9 @@ let mysql_stmt_num_rows stmt =
 let mysql_stmt_affected_rows stmt =
   Unsigned.ULLong.to_int @@ B.mysql_stmt_affected_rows stmt
 
+let mysql_stmt_insert_id stmt =
+  Unsigned.ULLong.to_int @@ B.mysql_stmt_insert_id stmt
+
 (* Blocking API *)
 
 let mysql_real_connect mysql host user pass db port socket flags =

lib/blocking.ml

@@ -166,6 +166,9 @@ module Res = struct
 
   let affected_rows =
     Common.Res.affected_rows
+
+  let insert_id =
+    Common.Res.insert_id
 end
 
 module Stmt = struct

lib/common.ml

@@ -227,6 +227,9 @@ module Res = struct
   let affected_rows res =
     B.mysql_stmt_affected_rows res.stmt
 
+  let insert_id res =
+    B.mysql_stmt_insert_id res.stmt
+
   let fetch_field raw i =
     coerce (ptr void) (ptr T.Field.t) (B.mysql_fetch_field_direct raw i)
 

lib/mariadb.ml

@@ -71,6 +71,7 @@ module type S = sig
 
     val num_rows : t -> int
     val affected_rows : t -> int
+    val insert_id : t -> int
     val fetch : (module Row.S with type t = 'r) -> t -> 'r option result
   end
 

lib/mariadb.mli

@@ -130,9 +130,15 @@ module type S = sig
           the execution of a [SELECT]-type query. *)
 
     val affected_rows : t -> int
-      (** [num_rows res] returns the number of affected rows in result [res]
+      (** [affected_rows res] returns the number of affected rows in result [res]
           after the execution of an [INSERT] or [UPDATE]-type query. *)
 
+    val insert_id : t -> int
+      (** [insert_id res] returns the ID generated by a prepared statement on a table
+          with a column having the [AUTO_INCREMENT] attribute. If the last query wasn't
+          an [INSERT] or [UPDATE] statement or if the modified table does not have a column
+          with the [AUTO_INCREMENT] attribute, this function will return zero. *)
+
     val fetch : (module Row.S with type t = 'r) -> t -> 'r option result
       (** [fetch (module M : Row.S) res] fetches the next available row
           from [res], returning it in as the data structure specified by
@@ -420,6 +426,7 @@ module Nonblocking : sig
 
       val num_rows : t -> int
       val affected_rows : t -> int
+      val insert_id : t -> int
       val fetch : (module Row.S with type t = 'r) -> t
                -> 'r option result future
     end

lib/nonblocking.ml

@@ -218,6 +218,9 @@ module Res = struct
   let affected_rows =
     Common.Res.affected_rows
 
+  let insert_id =
+    Common.Res.insert_id
+
   let handle_fetch (type t) (module R : Row.S with type t = t) res = function
     | 0, 0 ->
         `Ok (Common.Res.build_row (module R) res)
@@ -428,6 +431,7 @@ module type S = sig
 
     val num_rows : t -> int
     val affected_rows : t -> int
+    val insert_id : t -> int
     val fetch : (module Row.S with type t = 'r) -> t -> 'r option result future
   end
 
@@ -618,6 +622,9 @@ module Make (W : Wait) : S with type 'a future = 'a W.IO.future = struct
     let affected_rows =
       Res.affected_rows
 
+    let insert_id =
+      Res.insert_id
+
     let free res =
       nonblocking res.Common.Res.mariadb (Res.free res)
   end