/*************************************************************************
/* Statement.java -- Interface for executing SQL statements.
/*
/* Copyright (c) 1999 Free Software Foundation, Inc.
/* Written by Aaron M. Renn (arenn@urbanophile.com)
/*
/* This library is free software; you can redistribute it and/or modify
/* it under the terms of the GNU Library General Public License as published 
/* by the Free Software Foundation, either version 2 of the License, or
/* (at your option) any later verion.
/*
/* This library is distributed in the hope that it will be useful, but
/* WITHOUT ANY WARRANTY; without even the implied warranty of
/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
/* GNU Library General Public License for more details.
/*
/* You should have received a copy of the GNU Library General Public License
/* along with this library; if not, write to the Free Software Foundation
/* Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307 USA
/*************************************************************************/

package java.sql;

/**
  * This interface provides a mechanism for executing SQL statements.
  *
  * @author Aaron M. Renn (arenn@urbanophile.com)
  */
public abstract interface Statement
{

/**
  * This method executes the specified SQL SELECT statement and returns a
  * (possibly empty) <code>ResultSet</code> with the results of the query.
  *
  * @param sql The SQL statement to execute.
  *
  * @return The result set of the SQL statement.
  *
  * @exception SQLException If an error occurs.
  */
public abstract ResultSet
executeQuery(String sql) throws SQLException;

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

/**
  * This method executes the specified SQL INSERT, UPDATE, or DELETE statement
  * and returns the number of rows affected, which may be 0.
  * 
  * @param sql The SQL statement to execute.
  *
  * @return The number of rows affected by the SQL statement.
  *
  * @exception SQLException If an error occurs.
  */
public abstract int
executeUpdate(String sql) throws SQLException;

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

/**
  * This method closes the statement and frees any associated resources.
  *
  * @exception SQLException If an error occurs.
  */
public abstract void
close() throws SQLException;

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

/**
  * This method returns the maximum length of any column value in bytes.
  *
  * @return The maximum length of any column value in bytes.
  *
  * @exception SQLException If an error occurs.
  */
public abstract int
getMaxFieldSize() throws SQLException;

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

/**
  * This method sets the limit for the maximum length of any column in bytes.
  *
  * @param maxsize The new maximum length of any column in bytes.
  *
  * @exception SQLException If an error occurs.
  */
public abstract void
setMaxFieldSize(int maxsize) throws SQLException;

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

/**
  * This method returns the maximum possible number of rows in a result set.
  *
  * @return The maximum possible number of rows in a result set.
  *
  * @exception SQLException If an error occurs.
  */
public abstract int
getMaxRows() throws SQLException;

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

/**
  * This method sets the maximum number of rows that can be present in a
  * result set.
  *
  * @param maxrows The maximum possible number of rows in a result set.
  *
  * @exception SQLException If an error occurs.
  */
public abstract void
setMaxRows(int maxrows) throws SQLException;

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

/**
  * This method sets the local escape processing mode on or off.  The
  * default value is on.
  *
  * @param escape <code>true</code> to enable local escape processing, 
  * <code>false</code> to disable it.
  *
  * @exception SQLException If an error occurs.
  */
public abstract void
setEscapeProcessing(boolean esacpe) throws SQLException;

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

/**
  * The method returns the number of seconds a statement may be in process
  * before timing out.  A value of 0 means there is no timeout.
  *
  * @return The SQL statement timeout in seconds.
  *
  * @exception SQLException If an error occurs.
  */
public abstract int
getQueryTimeout() throws SQLException;

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

/**
  * This method sets the number of seconds a statement may be in process
  * before timing out.  A value of 0 means there is no timeout.
  *
  * @param timeout The new SQL statement timeout value.
  *
  * @exception SQLException If an error occurs.
  */
public abstract void
setQueryTimeout(int timeout) throws SQLException;

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

/**
  * This method cancels an outstanding statement, if the database supports
  * that operation.
  *
  * @exception SQLException If an error occurs.
  */
public abstract void
cancel() throws SQLException;

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

/**
  * This method returns the first SQL warning attached to this statement.
  * Subsequent warnings will be chained to this one.
  *
  * @return The first SQL warning for this statement.
  *
  * @exception SQLException If an error occurs.
  */
public abstract SQLWarning
getWarnings() throws SQLException;

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

/**
  * This method clears any SQL warnings that have been attached to this
  * statement.
  *
  * @exception SQLException If an error occurs.
  */
public abstract void
clearWarnings() throws SQLException;

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

/**
  * This method sets the cursor name that will be used by the result set.
  *
  * @param name The cursor name to use for this statement.
  *
  * @exception SQLException If an error occurs.
  */
public abstract void
setCursorName(String name) throws SQLException;

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

/**
  * This method executes an arbitrary SQL statement of any time.  The
  * methods <code>getResultSet</code>, <code>getMoreResults</code> and
  * <code>getUpdateCount</code> retrieve the results.
  *
  * @return <code>true</code> if a result set was returned, <code>false</code>
  * if an update count was returned.
  *
  * @exception SQLException If an error occurs.
  */
public abstract boolean
execute(String sql) throws SQLException;

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

/**
  * This method returns the result set of the SQL statement that was
  * executed.  This should be called only once per result set returned.
  *
  * @return The result set of the query, or <code>null</code> if there was
  * no result set (for example, if the statement was an UPDATE).
  *
  * @exception SQLException If an error occurs.
  *
  * @see execute
  */
public abstract ResultSet
getResultSet() throws SQLException;

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

/**
  * This method returns the update count of the SQL statement that was
  * executed.  This should be called only once per executed SQL statement.
  *
  * @return The update count of the query, or -1 if there was no update
  * count (for example, if the statement was a SELECT).
  *
  * @exception SQLException If an error occurs.
  *
  * @see execute
  */
public abstract int
getUpdateCount() throws SQLException;

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

/**
  * This method advances the result set pointer to the next result set, 
  * which can then be retrieved using <code>getResultSet</code>
  *
  * @return <code>true</code> if there is another result set, 
  * <code>false</code> otherwise (for example, the next result is an
  * update count).
  *
  * @exception SQLException If an error occurs.
  *
  * @see execute
  */
public abstract boolean
getMoreResults() throws SQLException;

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

/**
  * This method returns the current direction that the driver thinks the
  * result set will be accessed int.
  *
  * @return The direction the result set will be accessed in (????)
  *
  * @exception SQLException If an error occurs.
  */
public abstract int
getFetchDirection() throws SQLException;

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

/**
  * This method informs the driver which direction the result set will
  * be accessed in.
  *
  * @param direction The direction the result set will be accessed in (?????)
  *
  * @exception SQLException If an error occurs.
  */
public abstract void
setFetchDirection(int direction) throws SQLException;
  
/*************************************************************************/

/**
  * This method returns the number of rows the driver believes should be
  * fetched from the database at a time.
  *
  * @return The number of rows that will be fetched from the database at a time.
  *
  * @exception SQLException If an error occurs.
  */
public abstract int
getFetchSize() throws SQLException;

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

/**
  * This method informs the driver how many rows it should fetch from the
  * database at a time.
  *
  * @param numrows The number of rows the driver should fetch at a time
  * to populate the result set.
  *
  * @exception SQLException If an error occurs.
  */
public abstract void
setFetchSize(int numrows) throws SQLException;

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

/**
  * This method returns the concurrency type of the result set for this
  * statement. This will be one of the concurrency types defined in
  * <code>ResultSet</code>.
  *
  * @return The concurrency type of the result set for this statement.
  *
  * @exception SQLException If an error occurs.
  *
  * @see ResultSet
  */
public abstract int
getResultSetConcurrency() throws SQLException;

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

/**
  * This method returns the result set type for this statement.  This will
  * be one of the result set types defined in <code>ResultSet</code>.
  *
  * @return The result set type for this statement.
  *
  * @exception SQLException If an error occurs.
  *
  * @see ResultSet
  */
public abstract int
getResultSetType() throws SQLException;

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

/**
  * This method adds a SQL statement to a SQL batch.  A driver is not
  * required to implement this method.
  *
  * @param sql The sql statement to add to the batch.
  *
  * @exception SQLException If an error occurs.
  */
public abstract void
addBatch(String sql) throws SQLException;

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

/**
  * This method clears out any SQL statements that have been populated in
  * the current batch.  A driver is not required to implement this method.
  *
  * @exception SQLException If an error occurs.
  */
public abstract void
clearBatch() throws SQLException;

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

/**
  * This method executes the SQL batch and returns an array of update
  * counts - one for each SQL statement in the batch - ordered in the same
  * order the statements were added to the batch.  A driver is not required
  * to implement this method.
  *
  * @return An array of update counts for this batch.
  *
  * @exception SQLException If an error occurs.
  */
public abstract int[]
executeBatch() throws SQLException;

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

/**
  * This method returns the <code>Connection</code> instance that was
  * used to create this object.
  *
  * @return The connection used to create this object.
  *
  * @exception SQLException If an error occurs.
  */
public abstract Connection
getConnection() throws SQLException;

} // interface Statement