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674 lines
20 KiB
Java
674 lines
20 KiB
Java
package postgresql;
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import java.io.*;
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import java.lang.*;
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import java.net.*;
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import java.util.*;
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import java.sql.*;
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import postgresql.*;
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/**
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* @version 1.0 15-APR-1997
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* @author <A HREF="mailto:adrian@hottub.org">Adrian Hall</A>
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*
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* A Connection represents a session with a specific database. Within the
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* context of a Connection, SQL statements are executed and results are
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* returned.
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*
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* A Connection's database is able to provide information describing
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* its tables, its supported SQL grammar, its stored procedures, the
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* capabilities of this connection, etc. This information is obtained
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* with the getMetaData method.
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*
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* <B>Note:</B> By default, the Connection automatically commits changes
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* after executing each statement. If auto-commit has been disabled, an
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* explicit commit must be done or database changes will not be saved.
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*
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* @see java.sql.Connection
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*/
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public class Connection implements java.sql.Connection
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{
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protected PG_Stream pg_stream;
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private String PG_HOST;
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private int PG_PORT;
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private String PG_USER;
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private String PG_PASSWORD;
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private String PG_DATABASE;
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private boolean PG_STATUS;
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private boolean PG_AUTH; // true, then password auth used
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public boolean CONNECTION_OK = true;
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public boolean CONNECTION_BAD = false;
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private int STARTUP_CODE = STARTUP_USER;
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private static final int STARTUP_USER = 7; // User auth
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private static final int STARTUP_PASS = 14; // Password auth
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private static final int STARTUP_LEN = 288; // Length of a startup packet
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private boolean autoCommit = true;
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private boolean readOnly = false;
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protected Driver this_driver;
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private String this_url;
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private String cursor = null; // The positioned update cursor name
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// This is false for US, true for European date formats
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protected boolean europeanDates = false;
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// Now handle notices as warnings, so things like "show" now work
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protected SQLWarning firstWarning = null;
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/**
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* Connect to a PostgreSQL database back end.
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*
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* @param host the hostname of the database back end
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* @param port the port number of the postmaster process
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* @param info a Properties[] thing of the user and password
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* @param database the database to connect to
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* @param u the URL of the connection
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* @param d the Driver instantation of the connection
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* @return a valid connection profile
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* @exception SQLException if a database access error occurs
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*/
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public Connection(String host, int port, Properties info, String database, String url, Driver d) throws SQLException
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{
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int len = STARTUP_LEN; // Length of a startup packet
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this_driver = d;
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this_url = new String(url);
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PG_DATABASE = new String(database);
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PG_PASSWORD = new String(info.getProperty("password"));
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PG_USER = new String(info.getProperty("user"));
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PG_PORT = port;
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PG_HOST = new String(host);
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PG_STATUS = CONNECTION_BAD;
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if(info.getProperty("auth") != null) {
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PG_AUTH=true;
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STARTUP_CODE=STARTUP_PASS;
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} else {
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STARTUP_CODE=STARTUP_USER;
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}
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try
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{
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pg_stream = new PG_Stream(host, port);
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} catch (IOException e) {
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throw new SQLException ("Connection failed: " + e.toString());
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}
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// Now we need to construct and send a startup packet
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try
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{
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pg_stream.SendInteger(len, 4); len -= 4;
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pg_stream.SendInteger(STARTUP_CODE, 4); len -= 4;
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pg_stream.Send(database.getBytes(), 64); len -= 64;
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pg_stream.Send(PG_USER.getBytes(), len);
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// Send the password packet if required
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if(PG_AUTH) {
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len=STARTUP_LEN;
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pg_stream.SendInteger(len, 4); len -= 4;
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pg_stream.SendInteger(STARTUP_PASS, 4); len -= 4;
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pg_stream.Send(PG_USER.getBytes(), PG_USER.length());
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len-=PG_USER.length();
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pg_stream.SendInteger(0,1); len -= 1;
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pg_stream.Send(PG_PASSWORD.getBytes(), len);
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}
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} catch (IOException e) {
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throw new SQLException("Connection failed: " + e.toString());
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}
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// Find out the date style by issuing the SQL: show datestyle
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// This actually issues a warning, and our own warning handling
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// code handles this itself.
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//
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// Also, this query replaced the NULL query issued to test the
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// connection.
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//
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clearWarnings();
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ExecSQL("show datestyle");
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// Mark the connection as ok, and cleanup
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clearWarnings();
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PG_STATUS = CONNECTION_OK;
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}
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/**
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* SQL statements without parameters are normally executed using
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* Statement objects. If the same SQL statement is executed many
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* times, it is more efficient to use a PreparedStatement
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*
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* @return a new Statement object
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* @exception SQLException passed through from the constructor
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*/
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public java.sql.Statement createStatement() throws SQLException
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{
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return new Statement(this);
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}
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/**
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* A SQL statement with or without IN parameters can be pre-compiled
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* and stored in a PreparedStatement object. This object can then
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* be used to efficiently execute this statement multiple times.
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*
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* <B>Note:</B> This method is optimized for handling parametric
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* SQL statements that benefit from precompilation if the drivers
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* supports precompilation. PostgreSQL does not support precompilation.
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* In this case, the statement is not sent to the database until the
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* PreparedStatement is executed. This has no direct effect on users;
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* however it does affect which method throws certain SQLExceptions
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*
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* @param sql a SQL statement that may contain one or more '?' IN
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* parameter placeholders
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* @return a new PreparedStatement object containing the pre-compiled
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* statement.
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* @exception SQLException if a database access error occurs.
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*/
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public java.sql.PreparedStatement prepareStatement(String sql) throws SQLException
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{
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return new PreparedStatement(this, sql);
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}
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/**
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* A SQL stored procedure call statement is handled by creating a
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* CallableStatement for it. The CallableStatement provides methods
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* for setting up its IN and OUT parameters and methods for executing
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* it.
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*
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* <B>Note:</B> This method is optimised for handling stored procedure
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* call statements. Some drivers may send the call statement to the
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* database when the prepareCall is done; others may wait until the
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* CallableStatement is executed. This has no direct effect on users;
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* however, it does affect which method throws certain SQLExceptions
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*
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* @param sql a SQL statement that may contain one or more '?' parameter
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* placeholders. Typically this statement is a JDBC function call
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* escape string.
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* @return a new CallableStatement object containing the pre-compiled
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* SQL statement
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* @exception SQLException if a database access error occurs
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*/
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public java.sql.CallableStatement prepareCall(String sql) throws SQLException
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{
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throw new SQLException("Callable Statements are not supported at this time");
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// return new CallableStatement(this, sql);
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}
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/**
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* A driver may convert the JDBC sql grammar into its system's
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* native SQL grammar prior to sending it; nativeSQL returns the
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* native form of the statement that the driver would have sent.
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*
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* @param sql a SQL statement that may contain one or more '?'
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* parameter placeholders
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* @return the native form of this statement
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* @exception SQLException if a database access error occurs
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*/
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public String nativeSQL(String sql) throws SQLException
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{
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return sql;
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}
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/**
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* If a connection is in auto-commit mode, than all its SQL
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* statements will be executed and committed as individual
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* transactions. Otherwise, its SQL statements are grouped
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* into transactions that are terminated by either commit()
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* or rollback(). By default, new connections are in auto-
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* commit mode. The commit occurs when the statement completes
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* or the next execute occurs, whichever comes first. In the
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* case of statements returning a ResultSet, the statement
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* completes when the last row of the ResultSet has been retrieved
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* or the ResultSet has been closed. In advanced cases, a single
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* statement may return multiple results as well as output parameter
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* values. Here the commit occurs when all results and output param
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* values have been retrieved.
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*
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* @param autoCommit - true enables auto-commit; false disables it
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* @exception SQLException if a database access error occurs
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*/
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public void setAutoCommit(boolean autoCommit) throws SQLException
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{
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if (this.autoCommit == autoCommit)
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return;
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if (autoCommit)
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ExecSQL("end");
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else
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ExecSQL("begin");
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this.autoCommit = autoCommit;
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}
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/**
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* gets the current auto-commit state
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*
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* @return Current state of the auto-commit mode
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* @exception SQLException (why?)
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* @see setAutoCommit
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*/
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public boolean getAutoCommit() throws SQLException
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{
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return this.autoCommit;
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}
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/**
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* The method commit() makes all changes made since the previous
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* commit/rollback permanent and releases any database locks currently
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* held by the Connection. This method should only be used when
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* auto-commit has been disabled. (If autoCommit == true, then we
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* just return anyhow)
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*
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* @exception SQLException if a database access error occurs
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* @see setAutoCommit
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*/
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public void commit() throws SQLException
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{
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if (autoCommit)
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return;
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ExecSQL("commit");
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autoCommit = true;
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ExecSQL("begin");
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autoCommit = false;
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}
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/**
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* The method rollback() drops all changes made since the previous
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* commit/rollback and releases any database locks currently held by
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* the Connection.
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*
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* @exception SQLException if a database access error occurs
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* @see commit
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*/
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public void rollback() throws SQLException
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{
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if (autoCommit)
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return;
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ExecSQL("rollback");
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autoCommit = true;
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ExecSQL("begin");
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autoCommit = false;
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}
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/**
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* In some cases, it is desirable to immediately release a Connection's
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* database and JDBC resources instead of waiting for them to be
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* automatically released (cant think why off the top of my head)
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*
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* <B>Note:</B> A Connection is automatically closed when it is
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* garbage collected. Certain fatal errors also result in a closed
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* connection.
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*
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* @exception SQLException if a database access error occurs
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*/
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public void close() throws SQLException
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{
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if (pg_stream != null)
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{
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try
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{
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pg_stream.close();
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} catch (IOException e) {}
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pg_stream = null;
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}
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}
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/**
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* Tests to see if a Connection is closed
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*
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* @return the status of the connection
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* @exception SQLException (why?)
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*/
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public boolean isClosed() throws SQLException
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{
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return (pg_stream == null);
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}
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/**
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* A connection's database is able to provide information describing
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* its tables, its supported SQL grammar, its stored procedures, the
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* capabilities of this connection, etc. This information is made
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* available through a DatabaseMetaData object.
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*
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* @return a DatabaseMetaData object for this connection
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* @exception SQLException if a database access error occurs
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*/
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public java.sql.DatabaseMetaData getMetaData() throws SQLException
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{
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return new DatabaseMetaData(this);
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}
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/**
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* You can put a connection in read-only mode as a hunt to enable
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* database optimizations
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*
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* <B>Note:</B> setReadOnly cannot be called while in the middle
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* of a transaction
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*
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* @param readOnly - true enables read-only mode; false disables it
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* @exception SQLException if a database access error occurs
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*/
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public void setReadOnly (boolean readOnly) throws SQLException
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{
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this.readOnly = readOnly;
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}
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/**
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* Tests to see if the connection is in Read Only Mode. Note that
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* we cannot really put the database in read only mode, but we pretend
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* we can by returning the value of the readOnly flag
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*
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* @return true if the connection is read only
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* @exception SQLException if a database access error occurs
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*/
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public boolean isReadOnly() throws SQLException
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{
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return readOnly;
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}
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/**
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* A sub-space of this Connection's database may be selected by
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* setting a catalog name. If the driver does not support catalogs,
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* it will silently ignore this request
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*
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* @exception SQLException if a database access error occurs
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*/
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public void setCatalog(String catalog) throws SQLException
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{
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// No-op
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}
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/**
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* Return the connections current catalog name, or null if no
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* catalog name is set, or we dont support catalogs.
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*
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* @return the current catalog name or null
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* @exception SQLException if a database access error occurs
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*/
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public String getCatalog() throws SQLException
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{
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return null;
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}
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/**
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* You can call this method to try to change the transaction
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* isolation level using one of the TRANSACTION_* values.
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*
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* <B>Note:</B> setTransactionIsolation cannot be called while
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* in the middle of a transaction
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*
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* @param level one of the TRANSACTION_* isolation values with
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* the exception of TRANSACTION_NONE; some databases may
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* not support other values
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* @exception SQLException if a database access error occurs
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* @see java.sql.DatabaseMetaData#supportsTransactionIsolationLevel
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*/
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public void setTransactionIsolation(int level) throws SQLException
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{
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throw new SQLException("Transaction Isolation Levels are not implemented");
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}
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/**
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* Get this Connection's current transaction isolation mode.
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*
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* @return the current TRANSACTION_* mode value
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* @exception SQLException if a database access error occurs
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*/
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public int getTransactionIsolation() throws SQLException
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{
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return java.sql.Connection.TRANSACTION_SERIALIZABLE;
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}
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/**
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* The first warning reported by calls on this Connection is
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* returned.
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*
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* <B>Note:</B> Sebsequent warnings will be changed to this
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* SQLWarning
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*
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* @return the first SQLWarning or null
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* @exception SQLException if a database access error occurs
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*/
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public SQLWarning getWarnings() throws SQLException
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{
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return firstWarning;
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}
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/**
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* After this call, getWarnings returns null until a new warning
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* is reported for this connection.
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*
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* @exception SQLException if a database access error occurs
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*/
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public void clearWarnings() throws SQLException
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{
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firstWarning = null;
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}
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// **********************************************************
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// END OF PUBLIC INTERFACE
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// **********************************************************
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/**
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* This adds a warning to the warning chain
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*/
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public void addWarning(String msg)
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{
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// Add the warning to the chain
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if(firstWarning!=null)
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firstWarning.setNextWarning(new SQLWarning(msg));
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else
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firstWarning = new SQLWarning(msg);
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// Now check for some specific messages
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// This is generated by the SQL "show datestyle"
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if(msg.startsWith("NOTICE:DateStyle")) {
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if(msg.indexOf("with US")==-1)
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europeanDates=true;
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else
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europeanDates=false;
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System.err.println("europeanDates="+europeanDates);
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}
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}
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/**
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* Send a query to the backend. Returns one of the ResultSet
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* objects.
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*
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* <B>Note:</B> there does not seem to be any method currently
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* in existance to return the update count.
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*
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* @param sql the SQL statement to be executed
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* @return a ResultSet holding the results
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* @exception SQLException if a database error occurs
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*/
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public synchronized ResultSet ExecSQL(String sql) throws SQLException
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{
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Field[] fields = null;
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Vector tuples = new Vector();
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byte[] buf = new byte[sql.length()];
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int fqp = 0;
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boolean hfr = false;
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String recv_status = null, msg;
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SQLException final_error = null;
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if (sql.length() > 8192)
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throw new SQLException("SQL Statement too long: " + sql);
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try
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{
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pg_stream.SendChar('Q');
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buf = sql.getBytes();
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pg_stream.Send(buf);
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pg_stream.SendChar(0);
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} catch (IOException e) {
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throw new SQLException("I/O Error: " + e.toString());
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}
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while (!hfr || fqp > 0)
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{
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int c = pg_stream.ReceiveChar();
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switch (c)
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{
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case 'A': // Asynchronous Notify
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int pid = pg_stream.ReceiveInteger(4);
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msg = pg_stream.ReceiveString(8192);
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break;
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case 'B': // Binary Data Transfer
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if (fields == null)
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throw new SQLException("Tuple received before MetaData");
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tuples.addElement(pg_stream.ReceiveTuple(fields.length, true));
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break;
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case 'C': // Command Status
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recv_status = pg_stream.ReceiveString(8192);
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if (fields != null)
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hfr = true;
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else
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{
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try
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{
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pg_stream.SendChar('Q');
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pg_stream.SendChar(' ');
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pg_stream.SendChar(0);
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} catch (IOException e) {
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throw new SQLException("I/O Error: " + e.toString());
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}
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fqp++;
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}
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break;
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case 'D': // Text Data Transfer
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if (fields == null)
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throw new SQLException("Tuple received before MetaData");
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tuples.addElement(pg_stream.ReceiveTuple(fields.length, false));
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break;
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case 'E': // Error Message
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msg = pg_stream.ReceiveString(4096);
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final_error = new SQLException(msg);
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hfr = true;
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break;
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case 'I': // Empty Query
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int t = pg_stream.ReceiveChar();
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if (t != 0)
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throw new SQLException("Garbled Data");
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if (fqp > 0)
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fqp--;
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|
if (fqp == 0)
|
|
hfr = true;
|
|
break;
|
|
case 'N': // Error Notification
|
|
msg = pg_stream.ReceiveString(4096);
|
|
PrintStream log = DriverManager.getLogStream();
|
|
if(log!=null) log.println(msg);
|
|
addWarning(msg);
|
|
break;
|
|
case 'P': // Portal Name
|
|
String pname = pg_stream.ReceiveString(8192);
|
|
break;
|
|
case 'T': // MetaData Field Description
|
|
if (fields != null)
|
|
throw new SQLException("Cannot handle multiple result groups");
|
|
fields = ReceiveFields();
|
|
break;
|
|
default:
|
|
throw new SQLException("Unknown Response Type: " + (char)c);
|
|
}
|
|
}
|
|
if (final_error != null)
|
|
throw final_error;
|
|
return new ResultSet(this, fields, tuples, recv_status, 1);
|
|
}
|
|
|
|
/**
|
|
* Receive the field descriptions from the back end
|
|
*
|
|
* @return an array of the Field object describing the fields
|
|
* @exception SQLException if a database error occurs
|
|
*/
|
|
private Field[] ReceiveFields() throws SQLException
|
|
{
|
|
int nf = pg_stream.ReceiveInteger(2), i;
|
|
Field[] fields = new Field[nf];
|
|
|
|
for (i = 0 ; i < nf ; ++i)
|
|
{
|
|
String typname = pg_stream.ReceiveString(8192);
|
|
int typid = pg_stream.ReceiveInteger(4);
|
|
int typlen = pg_stream.ReceiveInteger(2);
|
|
fields[i] = new Field(this, typname, typid, typlen);
|
|
}
|
|
return fields;
|
|
}
|
|
|
|
/**
|
|
* In SQL, a result table can be retrieved through a cursor that
|
|
* is named. The current row of a result can be updated or deleted
|
|
* using a positioned update/delete statement that references the
|
|
* cursor name.
|
|
*
|
|
* We support one cursor per connection.
|
|
*
|
|
* setCursorName sets the cursor name.
|
|
*
|
|
* @param cursor the cursor name
|
|
* @exception SQLException if a database access error occurs
|
|
*/
|
|
public void setCursorName(String cursor) throws SQLException
|
|
{
|
|
this.cursor = cursor;
|
|
}
|
|
|
|
/**
|
|
* getCursorName gets the cursor name.
|
|
*
|
|
* @return the current cursor name
|
|
* @exception SQLException if a database access error occurs
|
|
*/
|
|
public String getCursorName() throws SQLException
|
|
{
|
|
return cursor;
|
|
}
|
|
|
|
/**
|
|
* We are required to bring back certain information by
|
|
* the DatabaseMetaData class. These functions do that.
|
|
*
|
|
* Method getURL() brings back the URL (good job we saved it)
|
|
*
|
|
* @return the url
|
|
* @exception SQLException just in case...
|
|
*/
|
|
public String getURL() throws SQLException
|
|
{
|
|
return this_url;
|
|
}
|
|
|
|
/**
|
|
* Method getUserName() brings back the User Name (again, we
|
|
* saved it)
|
|
*
|
|
* @return the user name
|
|
* @exception SQLException just in case...
|
|
*/
|
|
public String getUserName() throws SQLException
|
|
{
|
|
return PG_USER;
|
|
}
|
|
|
|
/**
|
|
* This method is not part of the Connection interface. Its is an extension
|
|
* that allows access to the PostgreSQL Large Object API
|
|
*
|
|
* @return PGlobj class that implements the API
|
|
*/
|
|
public PGlobj getLargeObjectAPI() throws SQLException
|
|
{
|
|
return new PGlobj(this);
|
|
}
|
|
}
|
|
|
|
// ***********************************************************************
|
|
|