Fix multi-order in a better way

First and Last do not order if query is already ordered (inspired by ActiveRecord)

main.go

@@ -294,8 +294,10 @@ func (s *DB) Assign(attrs ...interface{}) *DB {
 func (s *DB) First(out interface{}, where ...interface{}) *DB {
 	newScope := s.NewScope(out)
 	newScope.Search.Limit(1)
-	return newScope.Set("gorm:order_by_primary_key", "ASC").
-		inlineCondition(where...).callCallbacks(s.parent.callbacks.queries).db
+	if len(newScope.Search.orders) == 0 {
+		newScope.Set("gorm:order_by_primary_key", "ASC")
+	}
+	return newScope.inlineCondition(where...).callCallbacks(s.parent.callbacks.queries).db
 }
 
 // Take return a record that match given conditions, the order will depend on the database implementation
@@ -309,8 +311,10 @@ func (s *DB) Take(out interface{}, where ...interface{}) *DB {
 func (s *DB) Last(out interface{}, where ...interface{}) *DB {
 	newScope := s.NewScope(out)
 	newScope.Search.Limit(1)
-	return newScope.Set("gorm:order_by_primary_key", "DESC").
-		inlineCondition(where...).callCallbacks(s.parent.callbacks.queries).db
+	if len(newScope.Search.orders) == 0 {
+		newScope.Set("gorm:order_by_primary_key", "DESC")
+	}
+	return newScope.inlineCondition(where...).callCallbacks(s.parent.callbacks.queries).db
 }
 
 // Find find records that match given conditions

scope.go

@@ -800,27 +800,9 @@ func (scope *Scope) orderSQL() string {
 		return ""
 	}
 
-	// We have to make sure, that one column is not used multiple times in the order by clause.
-	// This would lead to an error on MSSQL.
-	// Therefore we create a map with just the column names and while creating the order by clause we may skip
-	// one or more columns
-	orderByColumnMap := make(map[string]bool, len(scope.Search.orders))
-
 	var orders []string
 	for _, order := range scope.Search.orders {
 		if str, ok := order.(string); ok {
-			columnName := str
-			columnNameLC := strings.ToLower(columnName)
-			if strings.HasSuffix(columnNameLC, " asc") {
-				columnName = columnName[0 : len(columnName)-4]
-			} else if strings.HasSuffix(columnNameLC, " desc") {
-				columnName = columnName[0 : len(columnName)-5]
-			}
-			if _, ok := orderByColumnMap[columnName]; ok {
-				continue
-			}
-			orderByColumnMap[columnName] = true
-
 			orders = append(orders, scope.quoteIfPossible(str))
 		} else if expr, ok := order.(*expr); ok {
 			exp := expr.expr