add update statement

select.go

@@ -30,6 +30,10 @@ func (q *SelectQuery) Args() []any {
 }
 
 func (q *SelectQuery) Columns(defs ...string) *SelectQuery {
+	if q.columns == nil {
+		q.columns = []Column{}
+	}
+
 	for _, def := range defs {
 		q.columns = append(q.columns, Column(def))
 	}
@@ -157,6 +161,10 @@ func (q *SelectQuery) String() string {
 }
 
 func (q *SelectQuery) Where(def string, args ...any) *SelectQuery {
+	if q.where == nil {
+		q.where = []Where{}
+	}
+
 	q.where = append(q.where, Where(def))
 
 	if len(args) > 0 {
@@ -172,10 +180,7 @@ func (q *SelectQuery) Where(def string, args ...any) *SelectQuery {
 
 func Select(from string) *SelectQuery {
 	q := &SelectQuery{
-		columns: []Column{},
-		tables:  []SelectTable{From(from)},
-
-		where: []Where{},
+		tables: []SelectTable{From(from)},
 	}
 
 	return q