/* Connection.java -- Manage a database connection.
   Copyright (C) 1999, 2000 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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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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02111-1307 USA.

Linking this library statically or dynamically with other modules is
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
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
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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.
  */
public static final 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.
  */
public static final 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.
  */
public static final 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.
  */
public static final 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.
  */
public static final 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
  */
public abstract Statement
createStatement() 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
  */
public abstract 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 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
  */
public abstract PreparedStatement
prepareStatement(String sql) 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
  */
public abstract 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 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
  */
public abstract CallableStatement
prepareCall(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 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
  */
public abstract CallableStatement
prepareCall(String sql, int resultSetType, int resultSetConcurrency) 
            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.
  */
public abstract String
nativeSQL(String sql) 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
  */
public abstract boolean
getAutoCommit() 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
  */
public abstract void
setAutoCommit(boolean autoCommit) throws SQLException;

/*************************************************************************/

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

/*************************************************************************/

/**
  * This method immediately closes this database connection.
  *
  * @exception SQLException If an error occurs.
  */
public abstract 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.
  */
public abstract 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
  */
public abstract DatabaseMetaData
getMetaData() 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.
  */
public abstract boolean
isReadOnly() 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.
  */
public abstract void
setReadOnly(boolean readOnly) 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.
  */
public abstract String
getCatalog() 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.
  */
public abstract void
setCatalog(String catalog) 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.
  */
public abstract int
getTransactionIsolation() 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.
  */
public abstract void
setTransactionIsolation(int level) 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.
  */
public abstract SQLWarning
getWarnings() throws SQLException;

/*************************************************************************/

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

} // interface Connection