PreparedStatement.setNull()

最新推荐文章于 2024-10-08 13:40:08 发布
原创 最新推荐文章于 2024-10-08 13:40:08 发布 · 515 阅读 · 0 ·
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#SQL

本文探讨了在数据库操作中setInt方法未赋值时默认取0的问题，并介绍了如何通过setNull方法将该值设为SQL NULL，包括setNull方法的参数说明和可能引发的SQLException。
setInt()没有值时总是会默认为0，要把它变成null


setNull
void setNull(int parameterIndex,
int sqlType)
throws SQLException将指定参数设置为 SQL NULL。
注：必须指定参数的 SQL 类型。


参数：
parameterIndex - 第一个参数是 1，第二个参数是 2，依此类推。
sqlType - java.sql.Types 中定义的 SQL 类型码
抛出：
SQLException - 如果发生数据库访问错误

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zhangzhangya
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PreparedStatement的setNull
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boolean isInParkingLot = rs.getBoolean("is_in_parking_lot"); VehicleType type = VehicleType.fromDescription(typeDesc); Vehicle vehicle = new Vehicle(plateNumber, color, type); vehicle.setArrivalTime(arrivalTime.toLocalDateTime()); if (departureTime != null) { vehicle.setDepartureTime(departureTime.toLocalDateTime()); } vehicle.setInParkingLot(isInParkingLot); vehicles.add(vehicle); } } return vehicles; } /** * 查询在场车辆 */ public List<Vehicle> selectVehiclesInParkingLot() throws SQLException { List<Vehicle> vehicles = new ArrayList<>(); try (Connection connection = getConnection(); PreparedStatement preparedStatement = connection.prepareStatement(SELECT_VEHICLES_IN_PARKING_LOT)) { ResultSet rs = preparedStatement.executeQuery(); while (rs.next()) { String plateNumber = rs.getString("plate_number"); String color = rs.getString("color"); String typeDesc = rs.getString("type"); Timestamp arrivalTime = rs.getTimestamp("arrival_time"); Timestamp departureTime = rs.getTimestamp("departure_time"); 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