我試圖插入表中沒有重複。我在Java中使用SQL derbyclient
。代碼不起作用(與'where not exists'
錯誤)。任何想法?JAVA,SQL,插入不重複
Connection connection = DriverManager.getConnection("jdbc:derby://localhost:1527/PetroleumDataStorageSystemDB;create=true");
PreparedStatement statement;
int i = 1;
int progress = 0;
for (Refuel refuelList1 : refuelList) {
progress = (i/refuelList.size()) * 100;
String sql = "INSERT INTO refuel (id_tank, time, fuel_volume, "
+ "refueling_speed) VALUES (?,?,?,?) "
+ "WHERE NOT EXISTS (SELECT * FROM refuel WHERE "
+ "id_tank = ? AND time = ? AND fuel_volume = ? AND "
+ "refueling_speed = ?)";
statement = connection.prepareStatement(sql, Statement.RETURN_GENERATED_KEYS);
statement.setInt(1, refuelList1.getTankID());
statement.setString(2, refuelList1.getTime());
statement.setDouble(3, refuelList1.getFuelVolume());
statement.setDouble(4, refuelList1.getRefuelingSpeed());
statement.execute();
i++;
}
我認爲這個ID是唯一的?如果是這種情況,那麼將它從不存在的地方移開,因爲它會不同? – Dane
什麼是您的rdbms –
Glassfish。該表沒有主鍵。 –