/* Connection.java -- Manage a database connection.
   Copyright (C) 1999, 2000, 2002 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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any later version.
 
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General Public License for more details.

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02111-1307 USA.

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making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
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package java.sql;

import java.util.Map;

/**
 * This interface provides methods for managing a connection to a database.
 *
 * @author Aaron M. Renn (arenn@urbanophile.com)
 */
public interface Connection 
{
  /**
   * This transaction isolation level indicates that transactions are not
   * supported.
   */
  int TRANSACTION_NONE = 0;

  /**
   * This transaction isolation level indicates that one transaction can
   * read modifications by other transactions before the other transactions
   * have committed their changes.  This could result in invalid reads.
   */
  int TRANSACTION_READ_UNCOMMITTED = 1;

  /**
   * This transaction isolation leve indicates that only committed data from
   * other transactions will be read.  If a transaction reads a row, then
   * another transaction commits a change to that row, the first transaction
   * would retrieve the changed row on subsequent reads of the same row.
   */
  int TRANSACTION_READ_COMMITTED = 2;

  /**
   * This transaction isolation level indicates that only committed data from
   * other transactions will be read.  It also ensures that data read from
   * a row will not be different on a subsequent read even if another
   * transaction commits a change.
   */
  int TRANSACTION_REPEATABLE_READ = 4;

  /**
   * This transaction isolation level indicates that only committed data from
   * other transactions will be read.  It also ensures that data read from
   * a row will not be different on a subsequent read even if another
   * transaction commits a change.  Additionally, rows modified by other
   * transactions will not affect the result set returned during subsequent
   * executions of the same WHERE clause in this transaction.
   */
  int TRANSACTION_SERIALIZABLE = 8;

  /**
   * This method creates a new SQL statement.  The default result set type
   * and concurrency will be used.
   *
   * @return A new <code>Statement</code> object. 
   * @exception SQLException If an error occurs.
   * @see Statement
   */
  Statement createStatement() throws SQLException;

  /**
   * This method creates a new <code>PreparedStatement</code> for the specified
   * SQL string.  This method is designed for use with parameterized
   * statements.  The default result set type and concurrency will be used.
   *
   * @param The SQL statement to use in creating this 
   *        <code>PreparedStatement</code>.
   * @return A new <code>PreparedStatement</code>.
   * @exception SQLException If an error occurs.
   * @see PreparedStatement
   */
  PreparedStatement prepareStatement(String sql) throws SQLException;

  /**
   * This method creates a new <code>CallableStatement</code> for the 
   * specified SQL string.  Thie method is designed to be used with
   * stored procedures.  The default result set type and concurrency
   * will be used.
   *
   * @param The SQL statement to use in creating this 
   *        <code>CallableStatement</code>.
   * @return A new <code>CallableStatement</code>.
   * @exception SQLException If an error occurs.
   * @see CallableStatement
   */
  CallableStatement prepareCall(String sql) throws SQLException;

  /**
   * This method converts the specified generic SQL statement into the
   * native grammer of the database this object is connected to.
   *
   * @param The JDBC generic SQL statement.
   * @return The native SQL statement.
   * @exception SQLException If an error occurs.
   */
  String nativeSQL(String sql) throws SQLException;

  /**
   * This method turns auto commit mode on or off.  In auto commit mode,
   * every SQL statement is committed its own transaction.  Otherwise a
   * transaction must be explicitly committed or rolled back.
   *
   * @param autoCommit <code>true</code> to enable auto commit mode,
   *        <code>false</code> to disable it.
   * @exception SQLException If an error occurs.
   * @see commit
   * @see rollback
   */
  void setAutoCommit(boolean autoCommit) throws SQLException;

  /**
   * This method tests whether or not auto commit mode is currently enabled.
   * In auto commit mode,  every SQL statement is committed its own transaction.
   * Otherwise a transaction must be explicitly committed or rolled back.
   *
   * @return <code>true</code> if auto commit mode is enabled, 
   * <code>false</code> otherwise.
   *
   * @exception SQLException If an error occurs.
   *
   * @see commit
   * @see rollback
   */
  boolean getAutoCommit() throws SQLException;

 /**
  * This method commits any SQL statements executed on this connection since 
  * the last commit or rollback.
  *
  * @exception SQLException If an error occurs.
  */
  void commit() throws SQLException;

  /**
   * This method rolls back any SQL statements executed on this connection
   * since the last commit or rollback.
   *
   * @exception SQLException If an error occurs.
   */
  void rollback() throws SQLException;

  /**
   * This method immediately closes this database connection.
   *
   * @exception SQLException If an error occurs.
   */
  void close() throws SQLException;

  /**
   * This method tests whether or not this connection has been closed. 
   *
   * @return <code>true</code> if the connection is closed, <code>false</code>
   *         otherwise.
   * @exception SQLException If an error occurs.
   */
  boolean isClosed() throws SQLException;

  /**
   * This method returns the meta data for this database connection.
   *
   * @return The meta data for this database.
   * @exception SQLException If an error occurs.
   * @see DatabaseMetaData
   */
  DatabaseMetaData getMetaData() throws SQLException;

  /**
   * This method turns read only mode on or off.  It may not be called while
   * a transaction is in progress.
   *
   * @param readOnly <code>true</code> if this connection is read only,
   *        <code>false</code> otherwise.
   * @exception SQLException If an error occurs.
   */
  void setReadOnly(boolean readOnly) throws SQLException;

  /**
   * This method tests whether or not this connection is in read only mode.
   *
   * @return <code>true</code> if the connection is read only <code>false</code>
   *         otherwise.
   * @exception SQLException If an error occurs.
   */
  boolean isReadOnly() throws SQLException;

  /**
   * This method sets the name of the catalog in use by this connection.
   * Note that this method does nothing if catalogs are not supported by
   * this database.
   *
   * @param catalog The name of the catalog to use for this connection.
   * @exception SQLException If an error occurs.
   */
  void setCatalog(String catalog) throws SQLException;

  /**
   * This method returns the name of the catalog in use by this connection,
   * if any.
   *
   * @return The name of the catalog, or <code>null</code> if one does not
   *         exist or catalogs are not supported by this database.
   * @exception SQLException If an error occurs.
   */
  String getCatalog() throws SQLException;

  /**
   * This method sets the current transaction isolation mode.  This must
   * be one of the constants defined in this interface.
   *
   * @param level The transaction isolation level.
   * @exception SQLException If an error occurs.
   */
  void setTransactionIsolation(int level) throws SQLException;

  /**
   * This method returns the current transaction isolation mode.  This will
   * be one of the constants defined in this interface.
   *
   * @return The transaction isolation level.
   * @exception SQLException If an error occurs.
   */
  int getTransactionIsolation() throws SQLException;

  /**
   * This method returns the first warning that occurred on this connection,
   * if any.  If there were any subsequence warnings, they will be chained
   * to the first one.
   *
   * @return The first <code>SQLWarning</code> that occurred, or 
   *         <code>null</code> if there have been no warnings.
   * @exception SQLException If an error occurs.
   */
  SQLWarning getWarnings() throws SQLException;

  /**
   * This method clears all warnings that have occurred on this connection.
   *
   * @exception SQLException If an error occurs.
   */
  void clearWarnings() throws SQLException;

  /**
   * This method creates a new SQL statement with the specified type and
   * concurrency.  Valid values for these parameters are specified in the
   * <code>ResultSet</code> class.
   *
   * @param resultSetType The type of result set to use for this statement.
   * @param resultSetConcurrency.  The type of concurrency to be used in
   *        the result set for this statement.
   * @return A new <code>Statement</code> object.
   * @exception SQLException If an error occurs.
   * @see Statement
   * @see ResultSet
   */
  Statement createStatement(int resultSetType, int resultSetConcurrency)
    throws SQLException;

  /**
   * This method creates a new <code>PreparedStatement</code> for the specified
   * SQL string.  This method is designed for use with parameterized
   * statements.  The specified result set type and concurrency will be used.
   * Valid values for these parameters are specified in the
   * <code>ResultSet</code> class.
   *
   * @param The SQL statement to use in creating this 
   *        <code>PreparedStatement</code>.
   * @param resultSetType The type of result set to use for this statement.
   * @param resultSetConcurrency.  The type of concurrency to be used in
   *        the result set for this statement.
   * @return A new <code>PreparedStatement</code>.
   * @exception SQLException If an error occurs.
   * @see PreparedStatement
   * @see ResultSet
   */
  PreparedStatement prepareStatement(String sql, int resultSetType, 
    int resultSetConcurrency) throws SQLException;

  /**
   * This method creates a new <code>CallableStatement</code> for the 
   * specified SQL string.  Thie method is designed to be used with
   * stored procedures.  The specified result set type and concurrency
   * will be used.  Valid values for these parameters are specified in the
   * <code>ResultSet</code> class.
   *
   * @param The SQL statement to use in creating this 
   *        <code>PreparedStatement</code>.
   * @param resultSetType The type of result set to use for this statement.
   * @param resultSetConcurrency.  The type of concurrency to be used in
   *        the result set for this statement.
   * @return A new <code>CallableStatement</code>.
   * @exception SQLException If an error occurs.
   * @see CallableStatement
   * @see ResultSet
   */
  CallableStatement prepareCall(String sql, int resultSetType, int
    resultSetConcurrency) throws SQLException;

  /**
   * This method returns the mapping of SQL types to Java classes
   * currently in use by this connection.  This mapping will have no
   * entries unless they have been manually added.
   *
   * @return The SQL type to Java class mapping.
   * @exception SQLException If an error occurs.
   */
  Map getTypeMap() throws SQLException;

  /**
   * This method sets the mapping table for SQL types to Java classes.
   * Any entries in this map override the defaults.
   *
   * @param map The new SQL mapping table.
   * @exception SQLException If an error occurs.
   */
  void setTypeMap(Map map) throws SQLException;

  /**
   * @since 1.4
   */
  void setHoldability(int holdability) throws SQLException;

  /**
   * @since 1.4
   */
  int getHoldability() throws SQLException;

  /**
   * @since 1.4
   */
  Savepoint setSavepoint() throws SQLException;

  /**
   * @since 1.4
   */
  Savepoint setSavepoint(String name) throws SQLException;

  /**
   * @since 1.4
   */
  void rollback(Savepoint savepoint) throws SQLException;

  /**
   * @since 1.4
   */
  void releaseSavepoint(Savepoint savepoint) throws SQLException;

  /**
   * @since 1.4
   */
  Statement createStatement(int resultSetType, int
      resultSetConcurrency, int resultSetHoldability) throws SQLException;

  /**
   * @since 1.4
   */
  PreparedStatement prepareStatement(String sql, int resultSetType, int
      resultSetConcurrency, int resultSetHoldability) throws SQLException;

  /**
   * @since 1.4
   */
  CallableStatement prepareCall(String sql, int resultSetType, int
      resultSetConcurrency, int resultSetHoldability) throws SQLException;

  /**
   * @since 1.4
   */
  PreparedStatement prepareStatement(String sql, int autoGeneratedKeys)
      throws SQLException;

  /**
   * @since 1.4
   */
  PreparedStatement prepareStatement(String sql, int[] columnIndexes)
      throws SQLException;

  /**
   * @since 1.4
   */
  PreparedStatement prepareStatement(String sql, String[] columnNames)
      throws SQLException;
}