Oracle 序列创建了两次。 ORA-00955: 名称已被现有对象使用

Question

编辑在你的建议之后，代码和错误。我现在收到错误 "ORA-00955: name is already used by an existing object"。每次调用 DataStoreManager 构造函数时，序列创建都会产生此错误。

现在是代码：

public class DataStoreManager {


    private Connection        connection;
    private PreparedStatement lookForAccount;
    private PreparedStatement addAccount;
    private PreparedStatement updaterBalance;

    private PreparedStatement reachOperation;

public DataStoreManager(String url, String user, String password) throws DataStoreException, SQLException {
      try {
          connection = DriverManager.getConnection(url,user,password);
          connection.setAutoCommit(false);

          this.createDB();

          lookForAccount = connection.prepareStatement("SELECT * FROM accounts WHERE account_id = ?");
          addAccount     = connection.prepareStatement("INSERT INTO accounts (account_id, balance) VALUES (? , 0.0)");
          updaterBalance = connection.prepareStatement("UPDATE accounts SET balance = ? WHERE account_id = ?"); 

          reachOperation = connection.prepareStatement("SELECT * FROM operations WHERE account_id = ? AND (date BETWEEN ? AND ?)");



      } catch (SQLException error) {
            error.printStackTrace();
            throw error;
      }
    }

public void createDB() throws DataStoreException {

      try {
              Statement statmnt = connection.createStatement();

            statmnt.executeUpdate("DROP TABLE operations");
            statmnt.executeUpdate("DROP TABLE accounts");

             statmnt.executeUpdate("CREATE TABLE accounts ( account_id INTEGER, balance DOUBLE PRECISION)");
             statmnt.executeUpdate("CREATE TABLE operations ( operation_id INTEGER, account_id INTEGER, amount DOUBLE PRECISION, mydate DATE NOT NULL)");



              //implement primary Key constraint.
              statmnt.executeUpdate("ALTER TABLE accounts ADD CONSTRAINT accounts_PK PRIMARY KEY ( account_id )");

              //implement foreign Key constraint
              statmnt.executeUpdate("ALTER TABLE operations ADD CONSTRAINT accountID FOREIGN KEY ( account_id )"
                    + "REFERENCES accounts ( account_id )");

              // implement sequence for auto implement.
              statmnt.executeUpdate("CREATE SEQUENCE operationID MINVALUE 1 START WITH 1 INCREMENT BY 1 CACHE 10");
              statmnt.executeUpdate("CREATE SEQUENCE logID MINVALUE 1 START WITH 1 INCREMENT BY 1 CACHE 10");

              // implement balance always positive constraint
              statmnt.executeUpdate("ALTER TABLE accounts ADD CONSTRAINT balance_must_be_positive CHECK (balance >= 0)");

              // Auto operation.
              statmnt.executeUpdate("CREATE TRIGGER addingOrder BEFORE UPDATE ON accounts FOR EACH ROW BEGIN"
                    + " INSERT INTO operations(operation_id, account_id, amount, mydate) "
                    + " VALUES (operationID.nextval, :OLD.account_id, :NEW.amount - :OLD.amount, SYSDATE) END");


          connection.commit();

      } catch (Exception error) {
            error.printStackTrace();
      }
  }


  public boolean createAccount(int number) throws DataStoreException, SQLException {

      try {

         lookForAccount.setInt(1, number);
         Boolean result = lookForAccount.execute();

         if(result == true)
         {
                addAccount.setInt(1, number);
                addAccount.executeUpdate();
                connection.commit();
                return true;

         }
         else
         { return false;}

      } catch (SQLException error) {
            error.printStackTrace();
            throw error;
      }
  }

这是我的错误：

   java.sql.SQLException: ORA-00955: name is already used by an existing object

    at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:134)
    at oracle.jdbc.ttc7.TTIoer.processError(TTIoer.java:289)
    at oracle.jdbc.ttc7.Oall7.receive(Oall7.java:590)
    at oracle.jdbc.ttc7.TTC7Protocol.doOall7(TTC7Protocol.java:1973)
    at oracle.jdbc.ttc7.TTC7Protocol.parseExecuteFetch(TTC7Protocol.java:1119)
    at oracle.jdbc.driver.OracleStatement.executeNonQuery(OracleStatement.java:2191)
    at oracle.jdbc.driver.OracleStatement.doExecuteOther(OracleStatement.java:2064)
    at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:2989)
    at oracle.jdbc.driver.OracleStatement.executeUpdate(OracleStatement.java:891)
    at services.DataStoreManager.createDB(DataStoreManager.java:105)
    at services.DataStoreManager.<init>(DataStoreManager.java:55)
    at application.SimpleTest.main(SimpleTest.java:145)
Running single-user tests...
Running multi-users tests...
java.sql.SQLException: ORA-00955: name is already used by an existing object

    at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:134)
    at oracle.jdbc.ttc7.TTIoer.processError(TTIoer.java:289)
    at oracle.jdbc.ttc7.Oall7.receive(Oall7.java:590)
    at oracle.jdbc.ttc7.TTC7Protocol.doOall7(TTC7Protocol.java:1973)
    at oracle.jdbc.ttc7.TTC7Protocol.parseExecuteFetch(TTC7Protocol.java:1119)
    at oracle.jdbc.driver.OracleStatement.executeNonQuery(OracleStatement.java:2191)
    at oracle.jdbc.driver.OracleStatement.doExecuteOther(OracleStatement.java:2064)
    at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:2989)
    at oracle.jdbc.driver.OracleStatement.executeUpdate(OracleStatement.java:891)
    at services.DataStoreManager.createDB(DataStoreManager.java:105)
    at services.DataStoreManager.<init>(DataStoreManager.java:55)
    at application.SimpleTest.main(SimpleTest.java:160)
user#0[services.DataStoreManager@e00c09]: starting
user#0[services.DataStoreManager@e00c09]: exiting
java.sql.SQLException: ORA-00955: name is already used by an existing object

    at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:134)
    at oracle.jdbc.ttc7.TTIoer.processError(TTIoer.java:289)
    at oracle.jdbc.ttc7.Oall7.receive(Oall7.java:590)
    at oracle.jdbc.ttc7.TTC7Protocol.doOall7(TTC7Protocol.java:1973)
    at oracle.jdbc.ttc7.TTC7Protocol.parseExecuteFetch(TTC7Protocol.java:1119)
    at oracle.jdbc.driver.OracleStatement.executeNonQuery(OracleStatement.java:2191)
    at oracle.jdbc.driver.OracleStatement.doExecuteOther(OracleStatement.java:2064)
    at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:2989)
    at oracle.jdbc.driver.OracleStatement.executeUpdate(OracleStatement.java:891)
    at services.DataStoreManager.createDB(DataStoreManager.java:105)
    at services.DataStoreManager.<init>(DataStoreManager.java:55)
    at application.SimpleTest.main(SimpleTest.java:160)
user#1[services.DataStoreManager@111f9b]: starting
user#1[services.DataStoreManager@111f9b]: exiting
java.sql.SQLException: ORA-00955: name is already used by an existing object

    at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:134)user#2[services.DataStoreManager@1363271]: starting
user#2[services.DataStoreManager@1363271]: exiting

    at oracle.jdbc.ttc7.TTIoer.processError(TTIoer.java:289)
    at oracle.jdbc.ttc7.Oall7.receive(Oall7.java:590)
    at oracle.jdbc.ttc7.TTC7Protocol.doOall7(TTC7Protocol.java:1973)
    at oracle.jdbc.ttc7.TTC7Protocol.parseExecuteFetch(TTC7Protocol.java:1119)
    at oracle.jdbc.driver.OracleStatement.executeNonQuery(OracleStatement.java:2191)
    at oracle.jdbc.driver.OracleStatement.doExecuteOther(OracleStatement.java:2064)
    at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:2989)
    at oracle.jdbc.driver.OracleStatement.executeUpdate(OracleStatement.java:891)
    at services.DataStoreManager.createDB(DataStoreManager.java:105)
    at services.DataStoreManager.<init>(DataStoreManager.java:55)
    at application.SimpleTest.main(SimpleTest.java:160)
java.sql.SQLException: ORA-00955: name is already used by an existing object

    at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:134)
    at oracle.jdbc.ttc7.TTIoer.processError(TTIoer.java:289)
    at oracle.jdbc.ttc7.Oall7.receive(Oall7.java:590)
    at oracle.jdbc.ttc7.TTC7Protocol.doOall7(TTC7Protocol.java:1973)
    at oracle.jdbc.ttc7.TTC7Protocol.parseExecuteFetch(TTC7Protocol.java:1119)
    at oracle.jdbc.driver.OracleStatement.executeNonQuery(OracleStatement.java:2191)
    at oracle.jdbc.driver.OracleStatement.doExecuteOther(OracleStatement.java:2064)
    at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:2989)
    at oracle.jdbc.driver.OracleStatement.executeUpdate(OracleStatement.java:891)
    at services.DataStoreManager.createDB(DataStoreManager.java:105)
    at services.DataStoreManager.<init>(DataStoreManager.java:55)
    at application.SimpleTest.main(SimpleTest.java:160)
user#3[services.DataStoreManager@114f313]: starting
user#3[services.DataStoreManager@114f313]: exiting
java.sql.SQLException: ORA-00955: name is already used by an existing object

    at oracle.jdbc.dbaccess.DBError.throwSqlException(DBError.java:134)user#4[services.DataStoreManager@d767dc]: starting
user#4[services.DataStoreManager@d767dc]: exiting

    at oracle.jdbc.ttc7.TTIoer.processError(TTIoer.java:289)
    at oracle.jdbc.ttc7.Oall7.receive(Oall7.java:590)
    at oracle.jdbc.ttc7.TTC7Protocol.doOall7(TTC7Protocol.java:1973)
    at oracle.jdbc.ttc7.TTC7Protocol.parseExecuteFetch(TTC7Protocol.java:1119)
    at oracle.jdbc.driver.OracleStatement.executeNonQuery(OracleStatement.java:2191)
    at oracle.jdbc.driver.OracleStatement.doExecuteOther(OracleStatement.java:2064)
    at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:2989)
    at oracle.jdbc.driver.OracleStatement.executeUpdate(OracleStatement.java:891)
    at services.DataStoreManager.createDB(DataStoreManager.java:105)
    at services.DataStoreManager.<init>(DataStoreManager.java:55)
    at application.SimpleTest.main(SimpleTest.java:160)

Answer 1

如果您的任何 SQL 语句产生错误（例如，如果 table 不存在并且您尝试删除它）。届时，您的代码将跳转到 catch 块，并且将创建数据库对象的 none。您需要将每个 DROP 语句包装在 try/catch 块中，以便可以捕获和处理任何错误（或者在您的情况下，忽略它可能是安全的），然后 CREATE 语句将运行 .

您的 table 也只是运行ning DROP 陈述。您需要对序列和触发器执行相同的操作。

您的触发器也无效。帐户 table 只有 account_id 和 balance 的列。您不能为操作 table 中的列引用 :old 或 :new 值。所以 :old.amount 和 :new.amount 是无效的，:old.account_id 是帐户 table 中的 account_id（结果与 account_id 在 operations table 中，因为它是外键）。您还缺少两个分号。它应该是这样的：

statmnt.executeUpdate("CREATE TRIGGER addingOrder BEFORE UPDATE ON accounts FOR EACH ROW BEGIN"
                    + " INSERT INTO operations(... columns ...) "
                    + " VALUES (... values ...); END;");

您对事物进行编码的方式是，您尝试先通过 DROPPING 一切进行清理，然后再 CREATE 一切。测试完成后，您将保留所有数据库对象。我建议您颠倒顺序，以便在测试开始时创建对象，然后在结束时拆除 DROP 一切，以便您的数据库保持干净。

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