diff --git a/storage/data/database_test.go b/storage/data/database_test.go
index ff641185d..5b18798fe 100644
--- a/storage/data/database_test.go
+++ b/storage/data/database_test.go
@@ -321,6 +321,13 @@ func testFeedback(t *testing.T, db Database) {
 	result, err = db.GetUserItemFeedback("100", "8")
 	assert.NoError(t, err)
 	assert.Empty(t, result)
+
+	// insert valid feedback and invalid feedback at the same time
+	err = db.BatchInsertFeedback([]Feedback{
+		{FeedbackKey: FeedbackKey{"a", "0", "8"}},
+		{FeedbackKey: FeedbackKey{"a", "100", "200"}},
+	}, false, false, false)
+	assert.NoError(t, err)
 }
 
 func testItems(t *testing.T, db Database) {
diff --git a/storage/data/sql.go b/storage/data/sql.go
index c5b4e01c5..3a9852d07 100644
--- a/storage/data/sql.go
+++ b/storage/data/sql.go
@@ -1067,8 +1067,11 @@ func (d *SQLDatabase) BatchInsertFeedback(feedback []Feedback, insertUser, inser
 		builder.WriteString("INSERT INTO feedback(feedback_type, user_id, item_id, time_stamp, comment) VALUES ")
 	}
 	var args []interface{}
-	for i, f := range feedback {
+	for _, f := range feedback {
 		if users.Has(f.UserId) && items.Has(f.ItemId) {
+			if len(args) > 0 {
+				builder.WriteString(",")
+			}
 			switch d.driver {
 			case MySQL:
 				builder.WriteString("(?,?,?,?,?)")
@@ -1082,9 +1085,6 @@ func (d *SQLDatabase) BatchInsertFeedback(feedback []Feedback, insertUser, inser
 				builder.WriteString(fmt.Sprintf("($%d,$%d,$%d,$%d,$%d)",
 					len(args)+1, len(args)+2, len(args)+3, len(args)+4, len(args)+5))
 			}
-			if i+1 < len(feedback) {
-				builder.WriteString(",")
-			}
 			args = append(args, f.FeedbackType, f.UserId, f.ItemId, f.Timestamp, f.Comment)
 		}
 	}