diff --git a/dbtool/dbtool.go b/dbtool/dbtool.go
index f6b5b63..5251364 100644
--- a/dbtool/dbtool.go
+++ b/dbtool/dbtool.go
@@ -74,6 +74,7 @@ func ResultToMap(r *sql.Rows) ([]map[string]interface{}, error) {
 		}
 		for i, v := range vals {
 			tmp[cols[i]] = v
+			vals[i] = nil
 		}
 		result = append(result, tmp)
 	}