add scan empty check

dbtool/dbtool.go

@@ -10,16 +10,19 @@ import (
 )
 
 // ScanToStruct - scan query rows to struct
-func ScanToStruct(rows *sql.Rows, ss interface{}) (err error) {
+func ScanToStruct(rows *sql.Rows, ss interface{}) (ok bool, err error) {
 	data, err := ResultToMap(rows)
 	if err != nil {
-		return err
+		return false, err
 	}
 	if len(data) == 0 {
-		return nil
+		return false, nil
 	}
 	err = MapToStruct(data[0], ss)
-	return nil
+	if err != nil {
+		return false, err
+	}
+	return true, nil
 }
 
 func ScanToStructAll(rows *sql.Rows, ss interface{}) error {