backend/src/main/java/com/tourguide/modules/user/mapper/GuideTeamMapper.java
@@ -15,7 +15,7 @@ "WHERE id = #{teamId} AND deleted = 0 AND balance >= #{amount}") int decreaseBalance(@Param("teamId") Long teamId, @Param("amount") BigDecimal amount); @Update("UPDATE guide_team SET balance = GREATEST(balance - #{amount}, 0), updated_at = NOW() " + @Update("UPDATE guide_team SET balance = COALESCE(balance, 0) - #{amount}, updated_at = NOW() " + "WHERE id = #{teamId} AND deleted = 0") int decreaseBalanceForRefund(@Param("teamId") Long teamId, @Param("amount") BigDecimal amount); }