Class TestDBConnection

  • All Implemented Interfaces:
    AutoCloseable, Connection, Wrapper

    public class TestDBConnection
    extends Object
    implements Connection
    A wrapper around another SQL connection that changes the following:

    1) Commits are blithely ignored 2) prepareStatement calls keep their string available

    • Constructor Detail

      • TestDBConnection

        public TestDBConnection​(Connection conn)
    • Method Detail

      • createStatement

        public Statement createStatement()
                                  throws SQLException
        Creates a Statement object for sending SQL statements to the database. SQL statements without parameters are normally executed using Statement objects. If the same SQL statement is executed many times, it may be more efficient to use a PreparedStatement object.

        Result sets created using the returned Statement object will by default be type TYPE_FORWARD_ONLY and have a concurrency level of CONCUR_READ_ONLY.

        Specified by:
        createStatement in interface Connection
        Returns:
        a new default Statement object
        Throws:
        SQLException - if a database access error occurs
      • prepareStatement

        public PreparedStatement prepareStatement​(String sql)
                                           throws SQLException
        Creates a PreparedStatement object for sending parameterized SQL statements to the database.

        A SQL statement with or without IN parameters can be pre-compiled and stored in a PreparedStatement object. This object can then be used to efficiently execute this statement multiple times.

        Note: This method is optimized for handling parametric SQL statements that benefit from precompilation. If the driver supports precompilation, the method prepareStatement will send the statement to the database for precompilation. Some drivers may not support precompilation. In this case, the statement may not be sent to the database until the PreparedStatement object is executed. This has no direct effect on users; however, it does affect which methods throw certain SQLException objects.

        Result sets created using the returned PreparedStatement object will by default be type TYPE_FORWARD_ONLY and have a concurrency level of CONCUR_READ_ONLY.

        Specified by:
        prepareStatement in interface Connection
        Parameters:
        sql - an SQL statement that may contain one or more '?' IN parameter placeholders
        Returns:
        a new default PreparedStatement object containing the pre-compiled SQL statement
        Throws:
        SQLException - if a database access error occurs
      • prepareCall

        public CallableStatement prepareCall​(String sql)
                                      throws SQLException
        Creates a CallableStatement object for calling database stored procedures. The CallableStatement object provides methods for setting up its IN and OUT parameters, and methods for executing the call to a stored procedure.

        Note: This method is optimized for handling stored procedure call statements. Some drivers may send the call statement to the database when the method prepareCall is done; others may wait until the CallableStatement object is executed. This has no direct effect on users; however, it does affect which method throws certain SQLExceptions.

        Result sets created using the returned CallableStatement object will by default be type TYPE_FORWARD_ONLY and have a concurrency level of CONCUR_READ_ONLY.

        Specified by:
        prepareCall in interface Connection
        Parameters:
        sql - an SQL statement that may contain one or more '?' parameter placeholders. Typically this statement is a JDBC function call escape string.
        Returns:
        a new default CallableStatement object containing the pre-compiled SQL statement
        Throws:
        SQLException - if a database access error occurs
      • nativeSQL

        public String nativeSQL​(String sql)
                         throws SQLException
        Converts the given SQL statement into the system's native SQL grammar. A driver may convert the JDBC SQL grammar into its system's native SQL grammar prior to sending it. This method returns the native form of the statement that the driver would have sent.
        Specified by:
        nativeSQL in interface Connection
        Parameters:
        sql - an SQL statement that may contain one or more '?' parameter placeholders
        Returns:
        the native form of this statement
        Throws:
        SQLException - if a database access error occurs
      • setAutoCommit

        public void setAutoCommit​(boolean autoCommit)
                           throws SQLException
        Sets this connection's auto-commit mode to the given state. If a connection is in auto-commit mode, then all its SQL statements will be executed and committed as individual transactions. Otherwise, its SQL statements are grouped into transactions that are terminated by a call to either the method commit or the method rollback. By default, new connections are in auto-commit mode.

        The commit occurs when the statement completes or the next execute occurs, whichever comes first. In the case of statements returning a ResultSet object, the statement completes when the last row of the ResultSet object has been retrieved or the ResultSet object has been closed. In advanced cases, a single statement may return multiple results as well as output parameter values. In these cases, the commit occurs when all results and output parameter values have been retrieved.

        NOTE: If this method is called during a transaction, the transaction is committed.

        Specified by:
        setAutoCommit in interface Connection
        Parameters:
        autoCommit - true to enable auto-commit mode; false to disable it
        Throws:
        SQLException - if a database access error occurs
        See Also:
        getAutoCommit()
      • getAutoCommit

        public boolean getAutoCommit()
                              throws SQLException
        Retrieves the current auto-commit mode for this Connection object.
        Specified by:
        getAutoCommit in interface Connection
        Returns:
        the current state of this Connection object's auto-commit mode
        Throws:
        SQLException - if a database access error occurs
        See Also:
        setAutoCommit(boolean)
      • commit

        public void commit()
                    throws SQLException
        Makes all changes made since the previous commit/rollback permanent and releases any database locks currently held by this Connection object. This method should be used only when auto-commit mode has been disabled.

        In the TestDBConnection 'implementation', commit is ignored, but the savepoints are still forgotten locally -- we will still be able to roll back the entire test.

        Specified by:
        commit in interface Connection
        Throws:
        SQLException - if a database access error occurs or this Connection object is in auto-commit mode
        See Also:
        setAutoCommit(boolean)
      • rollback

        public void rollback()
                      throws SQLException
        Undoes all changes made in the current transaction and releases any database locks currently held by this Connection object. This method should be used only when auto-commit mode has been disabled.
        Specified by:
        rollback in interface Connection
        Throws:
        SQLException - if a database access error occurs or this Connection object is in auto-commit mode
        See Also:
        setAutoCommit(boolean)
      • close

        public void close()
                   throws SQLException
        Releases this Connection object's database and JDBC resources immediately instead of waiting for them to be automatically released.

        Calling the method close on a Connection object that is already closed is a no-op.

        Note: A Connection object is automatically closed when it is garbage collected. Certain fatal errors also close a Connection object.

        Specified by:
        close in interface AutoCloseable
        Specified by:
        close in interface Connection
        Throws:
        SQLException - if a database access error occurs
      • isClosed

        public boolean isClosed()
                         throws SQLException
        Retrieves whether this Connection object has been closed. A connection is closed if the method close has been called on it or if certain fatal errors have occurred. This method is guaranteed to return true only when it is called after the method Connection.close has been called.

        This method generally cannot be called to determine whether a connection to a database is valid or invalid. A typical client can determine that a connection is invalid by catching any exceptions that might be thrown when an operation is attempted.

        Specified by:
        isClosed in interface Connection
        Returns:
        true if this Connection object is closed; false if it is still open
        Throws:
        SQLException - if a database access error occurs
      • getMetaData

        public DatabaseMetaData getMetaData()
                                     throws SQLException
        Retrieves a DatabaseMetaData object that contains metadata about the database to which this Connection object represents a connection. The metadata includes information about the database's tables, its supported SQL grammar, its stored procedures, the capabilities of this connection, and so on.
        Specified by:
        getMetaData in interface Connection
        Returns:
        a DatabaseMetaData object for this Connection object
        Throws:
        SQLException - if a database access error occurs
      • setReadOnly

        public void setReadOnly​(boolean readOnly)
                         throws SQLException
        Puts this connection in read-only mode as a hint to the driver to enable database optimizations.

        Note: This method cannot be called during a transaction.

        Specified by:
        setReadOnly in interface Connection
        Parameters:
        readOnly - true enables read-only mode; false disables it
        Throws:
        SQLException - if a database access error occurs or this method is called during a transaction
      • isReadOnly

        public boolean isReadOnly()
                           throws SQLException
        Retrieves whether this Connection object is in read-only mode.
        Specified by:
        isReadOnly in interface Connection
        Returns:
        true if this Connection object is read-only; false otherwise
        Throws:
        SQLException - if a database access error occurs
      • setCatalog

        public void setCatalog​(String catalog)
                        throws SQLException
        Sets the given catalog name in order to select a subspace of this Connection object's database in which to work.

        If the driver does not support catalogs, it will silently ignore this request.

        Specified by:
        setCatalog in interface Connection
        Parameters:
        catalog - the name of a catalog (subspace in this Connection object's database) in which to work
        Throws:
        SQLException - if a database access error occurs
        See Also:
        getCatalog()
      • setTransactionIsolation

        public void setTransactionIsolation​(int level)
                                     throws SQLException
        Attempts to change the transaction isolation level for this Connection object to the one given. The constants defined in the interface Connection are the possible transaction isolation levels.

        Note: If this method is called during a transaction, the result is implementation-defined.

        Specified by:
        setTransactionIsolation in interface Connection
        Parameters:
        level - one of the following Connection constants: Connection.TRANSACTION_READ_UNCOMMITTED, Connection.TRANSACTION_READ_COMMITTED, Connection.TRANSACTION_REPEATABLE_READ, or Connection.TRANSACTION_SERIALIZABLE. (Note that Connection.TRANSACTION_NONE cannot be used because it specifies that transactions are not supported.)
        Throws:
        SQLException - if a database access error occurs or the given parameter is not one of the Connection constants
        See Also:
        DatabaseMetaData.supportsTransactionIsolationLevel(int), getTransactionIsolation()
      • getTransactionIsolation

        public int getTransactionIsolation()
                                    throws SQLException
        Retrieves this Connection object's current transaction isolation level.
        Specified by:
        getTransactionIsolation in interface Connection
        Returns:
        the current transaction isolation level, which will be one of the following constants: Connection.TRANSACTION_READ_UNCOMMITTED, Connection.TRANSACTION_READ_COMMITTED, Connection.TRANSACTION_REPEATABLE_READ, Connection.TRANSACTION_SERIALIZABLE, or Connection.TRANSACTION_NONE.
        Throws:
        SQLException - if a database access error occurs
        See Also:
        setTransactionIsolation(int)
      • getWarnings

        public SQLWarning getWarnings()
                               throws SQLException
        Retrieves the first warning reported by calls on this Connection object. If there is more than one warning, subsequent warnings will be chained to the first one and can be retrieved by calling the method SQLWarning.getNextWarning on the warning that was retrieved previously.

        This method may not be called on a closed connection; doing so will cause an SQLException to be thrown.

        Note: Subsequent warnings will be chained to this SQLWarning.

        Specified by:
        getWarnings in interface Connection
        Returns:
        the first SQLWarning object or null if there are none
        Throws:
        SQLException - if a database access error occurs or this method is called on a closed connection
        See Also:
        SQLWarning
      • clearWarnings

        public void clearWarnings()
                           throws SQLException
        Clears all warnings reported for this Connection object. After a call to this method, the method getWarnings returns null until a new warning is reported for this Connection object.
        Specified by:
        clearWarnings in interface Connection
        Throws:
        SQLException - if a database access error occurs
      • createStatement

        public Statement createStatement​(int resultSetType,
                                         int resultSetConcurrency)
                                  throws SQLException
        Creates a Statement object that will generate ResultSet objects with the given type and concurrency. This method is the same as the createStatement method above, but it allows the default result set type and concurrency to be overridden.
        Specified by:
        createStatement in interface Connection
        Parameters:
        resultSetType - a result set type; one of ResultSet.TYPE_FORWARD_ONLY, ResultSet.TYPE_SCROLL_INSENSITIVE, or ResultSet.TYPE_SCROLL_SENSITIVE
        resultSetConcurrency - a concurrency type; one of ResultSet.CONCUR_READ_ONLY or ResultSet.CONCUR_UPDATABLE
        Returns:
        a new Statement object that will generate ResultSet objects with the given type and concurrency
        Throws:
        SQLException - if a database access error occurs or the given parameters are not ResultSet constants indicating type and concurrency
      • prepareStatement

        public PreparedStatement prepareStatement​(String sql,
                                                  int resultSetType,
                                                  int resultSetConcurrency)
                                           throws SQLException
        Creates a PreparedStatement object that will generate ResultSet objects with the given type and concurrency. This method is the same as the prepareStatement method above, but it allows the default result set type and concurrency to be overridden.
        Specified by:
        prepareStatement in interface Connection
        Parameters:
        sql - a String object that is the SQL statement to be sent to the database; may contain one or more ? IN parameters
        resultSetType - a result set type; one of ResultSet.TYPE_FORWARD_ONLY, ResultSet.TYPE_SCROLL_INSENSITIVE, or ResultSet.TYPE_SCROLL_SENSITIVE
        resultSetConcurrency - a concurrency type; one of ResultSet.CONCUR_READ_ONLY or ResultSet.CONCUR_UPDATABLE
        Returns:
        a new PreparedStatement object containing the pre-compiled SQL statement that will produce ResultSet objects with the given type and concurrency
        Throws:
        SQLException - if a database access error occurs or the given parameters are not ResultSet constants indicating type and concurrency
      • prepareCall

        public CallableStatement prepareCall​(String sql,
                                             int resultSetType,
                                             int resultSetConcurrency)
                                      throws SQLException
        Creates a CallableStatement object that will generate ResultSet objects with the given type and concurrency. This method is the same as the prepareCall method above, but it allows the default result set type and concurrency to be overridden.
        Specified by:
        prepareCall in interface Connection
        Parameters:
        sql - a String object that is the SQL statement to be sent to the database; may contain on or more ? parameters
        resultSetType - a result set type; one of ResultSet.TYPE_FORWARD_ONLY, ResultSet.TYPE_SCROLL_INSENSITIVE, or ResultSet.TYPE_SCROLL_SENSITIVE
        resultSetConcurrency - a concurrency type; one of ResultSet.CONCUR_READ_ONLY or ResultSet.CONCUR_UPDATABLE
        Returns:
        a new CallableStatement object containing the pre-compiled SQL statement that will produce ResultSet objects with the given type and concurrency
        Throws:
        SQLException - if a database access error occurs or the given parameters are not ResultSet constants indicating type and concurrency
      • setTypeMap

        public void setTypeMap​(Map<String,​Class<?>> map)
                        throws SQLException
        Installs the given TypeMap object as the type map for this Connection object. The type map will be used for the custom mapping of SQL structured types and distinct types.
        Specified by:
        setTypeMap in interface Connection
        Parameters:
        map - the java.util.Map object to install as the replacement for this Connection object's default type map
        Throws:
        SQLException - if a database access error occurs or the given parameter is not a java.util.Map object
        See Also:
        getTypeMap()
      • setHoldability

        public void setHoldability​(int holdability)
                            throws SQLException
        Changes the holdability of ResultSet objects created using this Connection object to the given holdability.
        Specified by:
        setHoldability in interface Connection
        Parameters:
        holdability - a ResultSet holdability constant; one of ResultSet.HOLD_CURSORS_OVER_COMMIT or ResultSet.CLOSE_CURSORS_AT_COMMIT
        Throws:
        SQLException - if a database access occurs, the given parameter is not a ResultSet constant indicating holdability, or the given holdability is not supported
        See Also:
        getHoldability(), ResultSet
      • getHoldability

        public int getHoldability()
                           throws SQLException
        Retrieves the current holdability of ResultSet objects created using this Connection object.
        Specified by:
        getHoldability in interface Connection
        Returns:
        the holdability, one of ResultSet.HOLD_CURSORS_OVER_COMMIT or ResultSet.CLOSE_CURSORS_AT_COMMIT
        Throws:
        SQLException - if a database access occurs
        See Also:
        setHoldability(int), ResultSet
      • setSavepoint

        public Savepoint setSavepoint()
                               throws SQLException
        Creates an unnamed savepoint in the current transaction and returns the new Savepoint object that represents it.
        Specified by:
        setSavepoint in interface Connection
        Returns:
        the new Savepoint object
        Throws:
        SQLException - if a database access error occurs or this Connection object is currently in auto-commit mode
        See Also:
        Savepoint
      • setSavepoint

        public Savepoint setSavepoint​(String name)
                               throws SQLException
        Creates a savepoint with the given name in the current transaction and returns the new Savepoint object that represents it.
        Specified by:
        setSavepoint in interface Connection
        Parameters:
        name - a String containing the name of the savepoint
        Returns:
        the new Savepoint object
        Throws:
        SQLException - if a database access error occurs or this Connection object is currently in auto-commit mode
        See Also:
        Savepoint
      • rollback

        public void rollback​(Savepoint savepoint)
                      throws SQLException
        Undoes all changes made after the given Savepoint object was set.

        This method should be used only when auto-commit has been disabled.

        Specified by:
        rollback in interface Connection
        Parameters:
        savepoint - the Savepoint object to roll back to
        Throws:
        SQLException - if a database access error occurs, the Savepoint object is no longer valid, or this Connection object is currently in auto-commit mode
        See Also:
        Savepoint, rollback()
      • releaseSavepoint

        public void releaseSavepoint​(Savepoint savepoint)
                              throws SQLException
        Removes the given Savepoint object from the current transaction. Any reference to the savepoint after it have been removed will cause an SQLException to be thrown.
        Specified by:
        releaseSavepoint in interface Connection
        Parameters:
        savepoint - the Savepoint object to be removed
        Throws:
        SQLException - if a database access error occurs or the given Savepoint object is not a valid savepoint in the current transaction
      • createStatement

        public Statement createStatement​(int resultSetType,
                                         int resultSetConcurrency,
                                         int resultSetHoldability)
                                  throws SQLException
        Creates a Statement object that will generate ResultSet objects with the given type, concurrency, and holdability. This method is the same as the createStatement method above, but it allows the default result set type, concurrency, and holdability to be overridden.
        Specified by:
        createStatement in interface Connection
        Parameters:
        resultSetType - one of the following ResultSet constants: ResultSet.TYPE_FORWARD_ONLY, ResultSet.TYPE_SCROLL_INSENSITIVE, or ResultSet.TYPE_SCROLL_SENSITIVE
        resultSetConcurrency - one of the following ResultSet constants: ResultSet.CONCUR_READ_ONLY or ResultSet.CONCUR_UPDATABLE
        resultSetHoldability - one of the following ResultSet constants: ResultSet.HOLD_CURSORS_OVER_COMMIT or ResultSet.CLOSE_CURSORS_AT_COMMIT
        Returns:
        a new Statement object that will generate ResultSet objects with the given type, concurrency, and holdability
        Throws:
        SQLException - if a database access error occurs or the given parameters are not ResultSet constants indicating type, concurrency, and holdability
        See Also:
        ResultSet
      • prepareStatement

        public PreparedStatement prepareStatement​(String sql,
                                                  int resultSetType,
                                                  int resultSetConcurrency,
                                                  int resultSetHoldability)
                                           throws SQLException
        Creates a PreparedStatement object that will generate ResultSet objects with the given type, concurrency, and holdability.

        This method is the same as the prepareStatement method above, but it allows the default result set type, concurrency, and holdability to be overridden.

        Specified by:
        prepareStatement in interface Connection
        Parameters:
        sql - a String object that is the SQL statement to be sent to the database; may contain one or more ? IN parameters
        resultSetType - one of the following ResultSet constants: ResultSet.TYPE_FORWARD_ONLY, ResultSet.TYPE_SCROLL_INSENSITIVE, or ResultSet.TYPE_SCROLL_SENSITIVE
        resultSetConcurrency - one of the following ResultSet constants: ResultSet.CONCUR_READ_ONLY or ResultSet.CONCUR_UPDATABLE
        resultSetHoldability - one of the following ResultSet constants: ResultSet.HOLD_CURSORS_OVER_COMMIT or ResultSet.CLOSE_CURSORS_AT_COMMIT
        Returns:
        a new PreparedStatement object, containing the pre-compiled SQL statement, that will generate ResultSet objects with the given type, concurrency, and holdability
        Throws:
        SQLException - if a database access error occurs or the given parameters are not ResultSet constants indicating type, concurrency, and holdability
        See Also:
        ResultSet
      • prepareCall

        public CallableStatement prepareCall​(String sql,
                                             int resultSetType,
                                             int resultSetConcurrency,
                                             int resultSetHoldability)
                                      throws SQLException
        Creates a CallableStatement object that will generate ResultSet objects with the given type and concurrency. This method is the same as the prepareCall method above, but it allows the default result set type, result set concurrency type and holdability to be overridden.
        Specified by:
        prepareCall in interface Connection
        Parameters:
        sql - a String object that is the SQL statement to be sent to the database; may contain on or more ? parameters
        resultSetType - one of the following ResultSet constants: ResultSet.TYPE_FORWARD_ONLY, ResultSet.TYPE_SCROLL_INSENSITIVE, or ResultSet.TYPE_SCROLL_SENSITIVE
        resultSetConcurrency - one of the following ResultSet constants: ResultSet.CONCUR_READ_ONLY or ResultSet.CONCUR_UPDATABLE
        resultSetHoldability - one of the following ResultSet constants: ResultSet.HOLD_CURSORS_OVER_COMMIT or ResultSet.CLOSE_CURSORS_AT_COMMIT
        Returns:
        a new CallableStatement object, containing the pre-compiled SQL statement, that will generate ResultSet objects with the given type, concurrency, and holdability
        Throws:
        SQLException - if a database access error occurs or the given parameters are not ResultSet constants indicating type, concurrency, and holdability
        See Also:
        ResultSet
      • prepareStatement

        public PreparedStatement prepareStatement​(String sql,
                                                  int autoGeneratedKeys)
                                           throws SQLException
        Creates a default PreparedStatement object that has the capability to retrieve auto-generated keys. The given constant tells the driver whether it should make auto-generated keys available for retrieval. This parameter is ignored if the SQL statement is not an INSERT statement.

        Note: This method is optimized for handling parametric SQL statements that benefit from precompilation. If the driver supports precompilation, the method prepareStatement will send the statement to the database for precompilation. Some drivers may not support precompilation. In this case, the statement may not be sent to the database until the PreparedStatement object is executed. This has no direct effect on users; however, it does affect which methods throw certain SQLExceptions.

        Result sets created using the returned PreparedStatement object will by default be type TYPE_FORWARD_ONLY and have a concurrency level of CONCUR_READ_ONLY.

        Specified by:
        prepareStatement in interface Connection
        Parameters:
        sql - an SQL statement that may contain one or more '?' IN parameter placeholders
        autoGeneratedKeys - a flag indicating whether auto-generated keys should be returned; one of Statement.RETURN_GENERATED_KEYS or Statement.NO_GENERATED_KEYS
        Returns:
        a new PreparedStatement object, containing the pre-compiled SQL statement, that will have the capability of returning auto-generated keys
        Throws:
        SQLException - if a database access error occurs or the given parameter is not a Statement constant indicating whether auto-generated keys should be returned
      • prepareStatement

        public PreparedStatement prepareStatement​(String sql,
                                                  int[] columnIndexes)
                                           throws SQLException
        Creates a default PreparedStatement object capable of returning the auto-generated keys designated by the given array. This array contains the indexes of the columns in the target table that contain the auto-generated keys that should be made available. This array is ignored if the SQL statement is not an INSERT statement.

        An SQL statement with or without IN parameters can be pre-compiled and stored in a PreparedStatement object. This object can then be used to efficiently execute this statement multiple times.

        Note: This method is optimized for handling parametric SQL statements that benefit from precompilation. If the driver supports precompilation, the method prepareStatement will send the statement to the database for precompilation. Some drivers may not support precompilation. In this case, the statement may not be sent to the database until the PreparedStatement object is executed. This has no direct effect on users; however, it does affect which methods throw certain SQLExceptions.

        Result sets created using the returned PreparedStatement object will by default be type TYPE_FORWARD_ONLY and have a concurrency level of CONCUR_READ_ONLY.

        Specified by:
        prepareStatement in interface Connection
        Parameters:
        sql - an SQL statement that may contain one or more '?' IN parameter placeholders
        columnIndexes - an array of column indexes indicating the columns that should be returned from the inserted row or rows
        Returns:
        a new PreparedStatement object, containing the pre-compiled statement, that is capable of returning the auto-generated keys designated by the given array of column indexes
        Throws:
        SQLException - if a database access error occurs
      • prepareStatement

        public PreparedStatement prepareStatement​(String sql,
                                                  String[] columnNames)
                                           throws SQLException
        Creates a default PreparedStatement object capable of returning the auto-generated keys designated by the given array. This array contains the names of the columns in the target table that contain the auto-generated keys that should be returned. This array is ignored if the SQL statement is not an INSERT statement.

        An SQL statement with or without IN parameters can be pre-compiled and stored in a PreparedStatement object. This object can then be used to efficiently execute this statement multiple times.

        Note: This method is optimized for handling parametric SQL statements that benefit from precompilation. If the driver supports precompilation, the method prepareStatement will send the statement to the database for precompilation. Some drivers may not support precompilation. In this case, the statement may not be sent to the database until the PreparedStatement object is executed. This has no direct effect on users; however, it does affect which methods throw certain SQLExceptions.

        Result sets created using the returned PreparedStatement object will by default be type TYPE_FORWARD_ONLY and have a concurrency level of CONCUR_READ_ONLY.

        Specified by:
        prepareStatement in interface Connection
        Parameters:
        sql - an SQL statement that may contain one or more '?' IN parameter placeholders
        columnNames - an array of column names indicating the columns that should be returned from the inserted row or rows
        Returns:
        a new PreparedStatement object, containing the pre-compiled statement, that is capable of returning the auto-generated keys designated by the given array of column names
        Throws:
        SQLException - if a database access error occurs