Fiexed:set ms.IgnoreUnknown true when length sqlFile is not 0

Author: bigxu

migrate.go

@@ -582,7 +582,8 @@ func (ms MigrationSet) PlanMigration(db *sql.DB, dialect string, m MigrationSour
 
 	// Make sure all migrations in the database are among the found migrations which
 	// are to be applied.
-	if !ms.IgnoreUnknown {
+	// patch for special sql file: len(sqlFiles) == 0
+	if !ms.IgnoreUnknown && len(sqlFiles) == 0 {
 		migrationsSearch := make(map[string]struct{})
 		for _, migration := range migrations {
 			migrationsSearch[migration.Id] = struct{}{}