Close jmoiron#238, support batch insert.

usage:
places := []*Place{&place1, &place2}
db.NamedExec("INSERT INTO place (country, telcode) VALUES (:country, :telcode)", places)

named.go

@@ -12,10 +12,12 @@ package sqlx
 //  * bindArgs, bindMapArgs, bindAnyArgs - given a list of names, return an arglist
 //
 import (
+	"bytes"
 	"database/sql"
 	"errors"
 	"fmt"
 	"reflect"
+	"regexp"
 	"strconv"
 	"unicode"
 
@@ -206,6 +208,47 @@ func bindStruct(bindType int, query string, arg interface{}, m *reflectx.Mapper)
 	return bound, arglist, nil
 }
 
+var (
+	EndBracketsReg = regexp.MustCompile(`\([^()]*\)\s*$`)
+)
+
+func fixBound(bound string, loop int) string {
+	endBrackets := EndBracketsReg.FindString(bound)
+	if endBrackets == "" {
+		return bound
+	}
+	var buffer bytes.Buffer
+	buffer.WriteString(bound)
+	for i := 0; i < loop-1; i++ {
+		buffer.WriteString(",")
+		buffer.WriteString(endBrackets)
+	}
+	return buffer.String()
+}
+
+// bindArray binds a named parameter query with fields from an array or slice of
+// structs argument.
+func bindArray(bindType int, query string, arg interface{}, m *reflectx.Mapper) (string, []interface{}, error) {
+	bound, names, err := compileNamedQuery([]byte(query), bindType)
+	if err != nil {
+		return "", []interface{}{}, err
+	}
+	arrayValue := reflect.ValueOf(arg)
+	arrayLen := arrayValue.Len()
+	var arglist []interface{}
+	for i := 0; i < arrayLen; i++ {
+		elemArglist, err := bindArgs(names, arrayValue.Index(i).Interface(), m)
+		if err != nil {
+			return "", []interface{}{}, err
+		}
+		arglist = append(arglist, elemArglist...)
+	}
+	if arrayLen > 1 {
+		bound = fixBound(bound, arrayLen)
+	}
+	return bound, arglist, nil
+}
+
 // bindMap binds a named parameter query with a map of arguments.
 func bindMap(bindType int, query string, args map[string]interface{}) (string, []interface{}, error) {
 	bound, names, err := compileNamedQuery([]byte(query), bindType)
@@ -318,7 +361,12 @@ func bindNamedMapper(bindType int, query string, arg interface{}, m *reflectx.Ma
 	if maparg, ok := arg.(map[string]interface{}); ok {
 		return bindMap(bindType, query, maparg)
 	}
-	return bindStruct(bindType, query, arg, m)
+	switch reflect.TypeOf(arg).Kind() {
+	case reflect.Array, reflect.Slice:
+		return bindArray(bindType, query, arg, m)
+	default:
+		return bindStruct(bindType, query, arg, m)
+	}
 }
 
 // NamedQuery binds a named query and then runs Query on the result using the