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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * under the terms of the GNU General Public License version 2 only, as

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 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

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 * This code 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 General Public License

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 * accompanied this code).

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 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

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 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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package java.sql;

import java.util.Properties;

import java.util.concurrent.Executor;

/**

 * <P>A connection (session) with a specific

 * database. SQL statements are executed and results are returned

 * within the context of a connection.

 * <P>

 * A <code>Connection</code> object's database is able to provide information

 * describing its tables, its supported SQL grammar, its stored

 * procedures, the capabilities of this connection, and so on. This

 * information is obtained with the <code>getMetaData</code> method.

 *

 * <P><B>Note:</B> When configuring a <code>Connection</code>, JDBC applications

 *  should use the appropriate <code>Connection</code> method such as

 *  <code>setAutoCommit</code> or <code>setTransactionIsolation</code>.

 *  Applications should not invoke SQL commands directly to change the connection's

 *   configuration when there is a JDBC method available.  By default a <code>Connection</code> object is in

 * auto-commit mode, which means that it automatically commits changes

 * after executing each statement. If auto-commit mode has been

 * disabled, the method <code>commit</code> must be called explicitly in

 * order to commit changes; otherwise, database changes will not be saved.

 * <P>

 * A new <code>Connection</code> object created using the JDBC 2.1 core API

 * has an initially empty type map associated with it. A user may enter a

 * custom mapping for a UDT in this type map.

 * When a UDT is retrieved from a data source with the

 * method <code>ResultSet.getObject</code>, the <code>getObject</code> method

 * will check the connection's type map to see if there is an entry for that

 * UDT.  If so, the <code>getObject</code> method will map the UDT to the

 * class indicated.  If there is no entry, the UDT will be mapped using the

 * standard mapping.

 * <p>

 * A user may create a new type map, which is a <code>java.util.Map</code>

 * object, make an entry in it, and pass it to the <code>java.sql</code>

 * methods that can perform custom mapping.  In this case, the method

 * will use the given type map instead of the one associated with

 * the connection.

 * <p>

 * For example, the following code fragment specifies that the SQL

 * type <code>ATHLETES</code> will be mapped to the class

 * <code>Athletes</code> in the Java programming language.

 * The code fragment retrieves the type map for the <code>Connection

 * </code> object <code>con</code>, inserts the entry into it, and then sets

 * the type map with the new entry as the connection's type map.

 * <pre>

 *      java.util.Map map = con.getTypeMap();

 *      map.put("mySchemaName.ATHLETES", Class.forName("Athletes"));

 *      con.setTypeMap(map);

 * </pre>

 *

 * @see DriverManager#getConnection

 * @see Statement

 * @see ResultSet

 * @see DatabaseMetaData

 * @since 1.1

 */

public interface Connection  extends Wrapper, AutoCloseable {

    /**

     * Creates a <code>Statement</code> object for sending

     * SQL statements to the database.

     * SQL statements without parameters are normally

     * executed using <code>Statement</code> objects. If the same SQL statement

     * is executed many times, it may be more efficient to use a

     * <code>PreparedStatement</code> object.

     * <P>

     * Result sets created using the returned <code>Statement</code>

     * object will by default be type <code>TYPE_FORWARD_ONLY</code>

     * and have a concurrency level of <code>CONCUR_READ_ONLY</code>.

     * The holdability of the created result sets can be determined by

     * calling {@link #getHoldability}.

     *

     * @return a new default <code>Statement</code> object

     * @exception SQLException if a database access error occurs

     * or this method is called on a closed connection

     */

    Statement createStatement() throws SQLException;

    /**

     * Creates a <code>PreparedStatement</code> object for sending

     * parameterized SQL statements to the database.

     * <P>

     * A SQL statement with or without IN parameters can be

     * pre-compiled and stored in a <code>PreparedStatement</code> object. This

     * object can then be used to efficiently execute this statement

     * multiple times.

     *

     * <P><B>Note:</B> This method is optimized for handling

     * parametric SQL statements that benefit from precompilation. If

     * the driver supports precompilation,

     * the method <code>prepareStatement</code> 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 <code>PreparedStatement</code>

     * object is executed.  This has no direct effect on users; however, it does

     * affect which methods throw certain <code>SQLException</code> objects.

     * <P>

     * Result sets created using the returned <code>PreparedStatement</code>

     * object will by default be type <code>TYPE_FORWARD_ONLY</code>

     * and have a concurrency level of <code>CONCUR_READ_ONLY</code>.

     * The holdability of the created result sets can be determined by

     * calling {@link #getHoldability}.

     *

     * @param sql an SQL statement that may contain one or more '?' IN

     * parameter placeholders

     * @return a new default <code>PreparedStatement</code> object containing the

     * pre-compiled SQL statement

     * @exception SQLException if a database access error occurs

     * or this method is called on a closed connection

     */

    PreparedStatement prepareStatement(String sql)

        throws SQLException;

    /**

     * Creates a <code>CallableStatement</code> object for calling

     * database stored procedures.

     * The <code>CallableStatement</code> object provides

     * methods for setting up its IN and OUT parameters, and

     * methods for executing the call to a stored procedure.

     *

     * <P><B>Note:</B> This method is optimized for handling stored

     * procedure call statements. Some drivers may send the call

     * statement to the database when the method <code>prepareCall</code>

     * is done; others

     * may wait until the <code>CallableStatement</code> object

     * is executed. This has no

     * direct effect on users; however, it does affect which method

     * throws certain SQLExceptions.

     * <P>

     * Result sets created using the returned <code>CallableStatement</code>

     * object will by default be type <code>TYPE_FORWARD_ONLY</code>

     * and have a concurrency level of <code>CONCUR_READ_ONLY</code>.

     * The holdability of the created result sets can be determined by

     * calling {@link #getHoldability}.

     *

     * @param sql an SQL statement that may contain one or more '?'

     * parameter placeholders. Typically this statement is specified using JDBC

     * call escape syntax.

     * @return a new default <code>CallableStatement</code> object containing the

     * pre-compiled SQL statement

     * @exception SQLException if a database access error occurs

     * or this method is called on a closed connection

     */

    CallableStatement prepareCall(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.

     *

     * @param sql an SQL statement that may contain one or more '?'

     * parameter placeholders

     * @return the native form of this statement

     * @exception SQLException if a database access error occurs

     * or this method is called on a closed connection

     */

    String nativeSQL(String sql) 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 <code>commit</code> or the method <code>rollback</code>.

     * By default, new connections are in auto-commit

     * mode.

     * <P>

     * The commit occurs when the statement completes. The time when the statement

     * completes depends on the type of SQL Statement:

     * <ul>

     * <li>For DML statements, such as Insert, Update or Delete, and DDL statements,

     * the statement is complete as soon as it has finished executing.

     * <li>For Select statements, the statement is complete when the associated result

     * set is closed.

     * <li>For <code>CallableStatement</code> objects or for statements that return

     * multiple results, the statement is complete

     * when all of the associated result sets have been closed, and all update

     * counts and output parameters have been retrieved.

     *</ul>

     * <P>

     * <B>NOTE:</B>  If this method is called during a transaction and the

     * auto-commit mode is changed, the transaction is committed.  If

     * <code>setAutoCommit</code> is called and the auto-commit mode is

     * not changed, the call is a no-op.

     *

     * @param autoCommit <code>true</code> to enable auto-commit mode;

     *         <code>false</code> to disable it

     * @exception SQLException if a database access error occurs,

     *  setAutoCommit(true) is called while participating in a distributed transaction,

     * or this method is called on a closed connection

     * @see #getAutoCommit

     */

    void setAutoCommit(boolean autoCommit) throws SQLException;

    /**

     * Retrieves the current auto-commit mode for this <code>Connection</code>

     * object.

     *

     * @return the current state of this <code>Connection</code> object's

     *         auto-commit mode

     * @exception SQLException if a database access error occurs

     * or this method is called on a closed connection

     * @see #setAutoCommit

     */

    boolean getAutoCommit() throws SQLException;

    /**

     * Makes all changes made since the previous

     * commit/rollback permanent and releases any database locks

     * currently held by this <code>Connection</code> object.

     * This method should be

     * used only when auto-commit mode has been disabled.

     *

     * @exception SQLException if a database access error occurs,

     * this method is called while participating in a distributed transaction,

     * if this method is called on a closed connection or this

     *            <code>Connection</code> object is in auto-commit mode

     * @see #setAutoCommit

     */

    void commit() throws SQLException;

    /**

     * Undoes all changes made in the current transaction

     * and releases any database locks currently held

     * by this <code>Connection</code> object. This method should be

     * used only when auto-commit mode has been disabled.

     *

     * @exception SQLException if a database access error occurs,

     * this method is called while participating in a distributed transaction,

     * this method is called on a closed connection or this

     *            <code>Connection</code> object is in auto-commit mode

     * @see #setAutoCommit

     */

    void rollback() throws SQLException;

    /**

     * Releases this <code>Connection</code> object's database and JDBC resources

     * immediately instead of waiting for them to be automatically released.

     * <P>

     * Calling the method <code>close</code> on a <code>Connection</code>

     * object that is already closed is a no-op.

     * <P>

     * It is <b>strongly recommended</b> that an application explicitly

     * commits or rolls back an active transaction prior to calling the

     * <code>close</code> method.  If the <code>close</code> method is called

     * and there is an active transaction, the results are implementation-defined.

     *

     * @exception SQLException if a database access error occurs

     */

    void close() throws SQLException;

    /**

     * Retrieves whether this <code>Connection</code> object has been

     * closed.  A connection is closed if the method <code>close</code>

     * has been called on it or if certain fatal errors have occurred.

     * This method is guaranteed to return <code>true</code> only when

     * it is called after the method <code>Connection.close</code> has

     * been called.

     * <P>

     * 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.

     *

     * @return <code>true</code> if this <code>Connection</code> object

     *         is closed; <code>false</code> if it is still open

     * @exception SQLException if a database access error occurs

     */

    boolean isClosed() throws SQLException;

    //======================================================================

    // Advanced features:

    /**

     * Retrieves a <code>DatabaseMetaData</code> object that contains

     * metadata about the database to which this

     * <code>Connection</code> 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.

     *

     * @return a <code>DatabaseMetaData</code> object for this

     *         <code>Connection</code> object

     * @exception  SQLException if a database access error occurs

     * or this method is called on a closed connection

     */

    DatabaseMetaData getMetaData() throws SQLException;

    /**

     * Puts this connection in read-only mode as a hint to the driver to enable

     * database optimizations.

     *

     * <P><B>Note:</B> This method cannot be called during a transaction.

     *

     * @param readOnly <code>true</code> enables read-only mode;

     *        <code>false</code> disables it

     * @exception SQLException if a database access error occurs, this

     *  method is called on a closed connection or this

     *            method is called during a transaction

     */

    void setReadOnly(boolean readOnly) throws SQLException;

    /**

     * Retrieves whether this <code>Connection</code>

     * object is in read-only mode.

     *

     * @return <code>true</code> if this <code>Connection</code> object

     *         is read-only; <code>false</code> otherwise

     * @exception SQLException if a database access error occurs

     * or this method is called on a closed connection

     */

    boolean isReadOnly() throws SQLException;

    /**

     * Sets the given catalog name in order to select

     * a subspace of this <code>Connection</code> object's database

     * in which to work.

     * <P>

     * If the driver does not support catalogs, it will

     * silently ignore this request.

     * <p>

     * Calling {@code setCatalog} has no effect on previously created or prepared

     * {@code Statement} objects. It is implementation defined whether a DBMS

     * prepare operation takes place immediately when the {@code Connection}

     * method {@code prepareStatement} or {@code prepareCall} is invoked.

     * For maximum portability, {@code setCatalog} should be called before a

     * {@code Statement} is created or prepared.

     *

     * @param catalog the name of a catalog (subspace in this

     *        <code>Connection</code> object's database) in which to work

     * @exception SQLException if a database access error occurs

     * or this method is called on a closed connection

     * @see #getCatalog

     */

    void setCatalog(String catalog) throws SQLException;

    /**

     * Retrieves this <code>Connection</code> object's current catalog name.

     *

     * @return the current catalog name or <code>null</code> if there is none

     * @exception SQLException if a database access error occurs

     * or this method is called on a closed connection

     * @see #setCatalog

     */

    String getCatalog() throws SQLException;

    /**

     * A constant indicating that transactions are not supported.

     */

    int TRANSACTION_NONE             = 0;

    /**

     * A constant indicating that

     * dirty reads, non-repeatable reads and phantom reads can occur.

     * This level allows a row changed by one transaction to be read

     * by another transaction before any changes in that row have been

     * committed (a "dirty read").  If any of the changes are rolled back,

     * the second transaction will have retrieved an invalid row.

     */

    int TRANSACTION_READ_UNCOMMITTED = 1;

    /**

     * A constant indicating that

     * dirty reads are prevented; non-repeatable reads and phantom

     * reads can occur.  This level only prohibits a transaction

     * from reading a row with uncommitted changes in it.

     */

    int TRANSACTION_READ_COMMITTED   = 2;

    /**

     * A constant indicating that

     * dirty reads and non-repeatable reads are prevented; phantom

     * reads can occur.  This level prohibits a transaction from

     * reading a row with uncommitted changes in it, and it also

     * prohibits the situation where one transaction reads a row,

     * a second transaction alters the row, and the first transaction

     * rereads the row, getting different values the second time

     * (a "non-repeatable read").

     */

    int TRANSACTION_REPEATABLE_READ  = 4;

    /**

     * A constant indicating that

     * dirty reads, non-repeatable reads and phantom reads are prevented.

     * This level includes the prohibitions in

     * <code>TRANSACTION_REPEATABLE_READ</code> and further prohibits the

     * situation where one transaction reads all rows that satisfy

     * a <code>WHERE</code> condition, a second transaction inserts a row that

     * satisfies that <code>WHERE</code> condition, and the first transaction

     * rereads for the same condition, retrieving the additional

     * "phantom" row in the second read.

     */

    int TRANSACTION_SERIALIZABLE     = 8;

    /**

     * Attempts to change the transaction isolation level for this

     * <code>Connection</code> object to the one given.

     * The constants defined in the interface <code>Connection</code>

     * are the possible transaction isolation levels.

     * <P>

     * <B>Note:</B> If this method is called during a transaction, the result

     * is implementation-defined.

     *

     * @param level one of the following <code>Connection</code> constants:

     *        <code>Connection.TRANSACTION_READ_UNCOMMITTED</code>,

     *        <code>Connection.TRANSACTION_READ_COMMITTED</code>,

     *        <code>Connection.TRANSACTION_REPEATABLE_READ</code>, or

     *        <code>Connection.TRANSACTION_SERIALIZABLE</code>.

     *        (Note that <code>Connection.TRANSACTION_NONE</code> cannot be used

     *        because it specifies that transactions are not supported.)

     * @exception SQLException if a database access error occurs, this

     * method is called on a closed connection

     *            or the given parameter is not one of the <code>Connection</code>

     *            constants

     * @see DatabaseMetaData#supportsTransactionIsolationLevel

     * @see #getTransactionIsolation

     */

    void setTransactionIsolation(int level) throws SQLException;

    /**

     * Retrieves this <code>Connection</code> object's current

     * transaction isolation level.

     *

     * @return the current transaction isolation level, which will be one

     *         of the following constants:

     *        <code>Connection.TRANSACTION_READ_UNCOMMITTED</code>,

     *        <code>Connection.TRANSACTION_READ_COMMITTED</code>,

     *        <code>Connection.TRANSACTION_REPEATABLE_READ</code>,

     *        <code>Connection.TRANSACTION_SERIALIZABLE</code>, or

     *        <code>Connection.TRANSACTION_NONE</code>.

     * @exception SQLException if a database access error occurs

     * or this method is called on a closed connection

     * @see #setTransactionIsolation

     */

    int getTransactionIsolation() throws SQLException;

    /**

     * Retrieves the first warning reported by calls on this

     * <code>Connection</code> 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

     * <code>SQLWarning.getNextWarning</code> on the warning

     * that was retrieved previously.

     * <P>

     * This method may not be

     * called on a closed connection; doing so will cause an

     * <code>SQLException</code> to be thrown.

     *

     * <P><B>Note:</B> Subsequent warnings will be chained to this

     * SQLWarning.

     *

     * @return the first <code>SQLWarning</code> object or <code>null</code>

     *         if there are none

     * @exception SQLException if a database access error occurs or

     *            this method is called on a closed connection

     * @see SQLWarning

     */

    SQLWarning getWarnings() throws SQLException;

    /**

     * Clears all warnings reported for this <code>Connection</code> object.

     * After a call to this method, the method <code>getWarnings</code>

     * returns <code>null</code> until a new warning is

     * reported for this <code>Connection</code> object.

     *

     * @exception SQLException if a database access error occurs

     * or this method is called on a closed connection

     */

    void clearWarnings() throws SQLException;

    //--------------------------JDBC 2.0-----------------------------

    /**

     * Creates a <code>Statement</code> object that will generate

     * <code>ResultSet</code> objects with the given type and concurrency.

     * This method is the same as the <code>createStatement</code> method

     * above, but it allows the default result set

     * type and concurrency to be overridden.

     * The holdability of the created result sets can be determined by

     * calling {@link #getHoldability}.

     *

     * @param resultSetType a result set type; one of

     *        <code>ResultSet.TYPE_FORWARD_ONLY</code>,

     *        <code>ResultSet.TYPE_SCROLL_INSENSITIVE</code>, or

     *        <code>ResultSet.TYPE_SCROLL_SENSITIVE</code>

     * @param resultSetConcurrency a concurrency type; one of

     *        <code>ResultSet.CONCUR_READ_ONLY</code> or

     *        <code>ResultSet.CONCUR_UPDATABLE</code>

     * @return a new <code>Statement</code> object that will generate

     *         <code>ResultSet</code> objects with the given type and

     *         concurrency

     * @exception SQLException if a database access error occurs, this

     * method is called on a closed connection

     *         or the given parameters are not <code>ResultSet</code>