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Diffstat (limited to 'src/interfaces/jdbc/postgresql/Statement.java')
-rw-r--r-- | src/interfaces/jdbc/postgresql/Statement.java | 306 |
1 files changed, 306 insertions, 0 deletions
diff --git a/src/interfaces/jdbc/postgresql/Statement.java b/src/interfaces/jdbc/postgresql/Statement.java new file mode 100644 index 00000000000..464a263621f --- /dev/null +++ b/src/interfaces/jdbc/postgresql/Statement.java @@ -0,0 +1,306 @@ +package postgresql; + +import java.sql.*; + +/** + * @version 1.0 15-APR-1997 + * @author <A HREF="mailto:[email protected]">Adrian Hall</A> + * + * A Statement object is used for executing a static SQL statement and + * obtaining the results produced by it. + * + * Only one ResultSet per Statement can be open at any point in time. + * Therefore, if the reading of one ResultSet is interleaved with the + * reading of another, each must have been generated by different + * Statements. All statement execute methods implicitly close a + * statement's current ResultSet if an open one exists. + * + * @see java.sql.Statement + * @see ResultSet + */ +public class Statement implements java.sql.Statement +{ + Connection connection; // The connection who created us + ResultSet result = null; // The current results + SQLWarning warnings = null; // The warnings chain. + int maxrows = 0; // maximum no. of rows; 0 = unlimited + int timeout = 0; // The timeout for a query (not used) + boolean escapeProcessing = true;// escape processing flag + + /** + * Constructor for a Statement. It simply sets the connection + * that created us. + * + * @param c the Connection instantation that creates us + */ + public Statement (Connection c) + { + connection = c; + } + + /** + * Execute a SQL statement that retruns a single ResultSet + * + * @param sql typically a static SQL SELECT statement + * @return a ResulSet that contains the data produced by the query + * @exception SQLException if a database access error occurs + */ + public java.sql.ResultSet executeQuery(String sql) throws SQLException + { + this.execute(sql); + while (result != null && !result.reallyResultSet()) + result = result.getNext(); + if (result == null) + throw new SQLException("no results returned"); + return result; + } + + /** + * Execute a SQL INSERT, UPDATE or DELETE statement. In addition + * SQL statements that return nothing such as SQL DDL statements + * can be executed + * + * @param sql a SQL statement + * @return either a row count, or 0 for SQL commands + * @exception SQLException if a database access error occurs + */ + public int executeUpdate(String sql) throws SQLException + { + this.execute(sql); + if (result.reallyResultSet()) + throw new SQLException("results returned"); + return this.getUpdateCount(); + } + + /** + * In many cases, it is desirable to immediately release a + * Statement's database and JDBC resources instead of waiting + * for this to happen when it is automatically closed. The + * close method provides this immediate release. + * + * <B>Note:</B> A Statement is automatically closed when it is + * garbage collected. When a Statement is closed, its current + * ResultSet, if one exists, is also closed. + * + * @exception SQLException if a database access error occurs (why?) + */ + public void close() throws SQLException + { + result = null; + } + + /** + * The maxFieldSize limit (in bytes) is the maximum amount of + * data returned for any column value; it only applies to + * BINARY, VARBINARY, LONGVARBINARY, CHAR, VARCHAR and LONGVARCHAR + * columns. If the limit is exceeded, the excess data is silently + * discarded. + * + * @return the current max column size limit; zero means unlimited + * @exception SQLException if a database access error occurs + */ + public int getMaxFieldSize() throws SQLException + { + return 8192; // We cannot change this + } + + /** + * Sets the maxFieldSize - NOT! - We throw an SQLException just + * to inform them to stop doing this. + * + * @param max the new max column size limit; zero means unlimited + * @exception SQLException if a database access error occurs + */ + public void setMaxFieldSize(int max) throws SQLException + { + throw new SQLException("Attempt to setMaxFieldSize failed - compile time default"); + } + + /** + * The maxRows limit is set to limit the number of rows that + * any ResultSet can contain. If the limit is exceeded, the + * excess rows are silently dropped. + * + * @return the current maximum row limit; zero means unlimited + * @exception SQLException if a database access error occurs + */ + public int getMaxRows() throws SQLException + { + return maxrows; + } + + /** + * Set the maximum number of rows + * + * @param max the new max rows limit; zero means unlimited + * @exception SQLException if a database access error occurs + * @see getMaxRows + */ + public void setMaxRows(int max) throws SQLException + { + maxrows = max; + } + + /** + * If escape scanning is on (the default), the driver will do escape + * substitution before sending the SQL to the database. + * + * @param enable true to enable; false to disable + * @exception SQLException if a database access error occurs + */ + public void setEscapeProcessing(boolean enable) throws SQLException + { + escapeProcessing = enable; + } + + /** + * The queryTimeout limit is the number of seconds the driver + * will wait for a Statement to execute. If the limit is + * exceeded, a SQLException is thrown. + * + * @return the current query timeout limit in seconds; 0 = unlimited + * @exception SQLException if a database access error occurs + */ + public int getQueryTimeout() throws SQLException + { + return timeout; + } + + /** + * Sets the queryTimeout limit + * + * @param seconds - the new query timeout limit in seconds + * @exception SQLException if a database access error occurs + */ + public void setQueryTimeout(int seconds) throws SQLException + { + timeout = seconds; + } + + /** + * Cancel can be used by one thread to cancel a statement that + * is being executed by another thread. However, PostgreSQL is + * a sync. sort of thing, so this really has no meaning - we + * define it as a no-op (i.e. you can't cancel, but there is no + * error if you try.) + * + * @exception SQLException only because thats the spec. + */ + public void cancel() throws SQLException + { + // No-op + } + + /** + * The first warning reported by calls on this Statement is + * returned. A Statement's execute methods clear its SQLWarning + * chain. Subsequent Statement warnings will be chained to this + * SQLWarning. + * + * The Warning chain is automatically cleared each time a statement + * is (re)executed. + * + * <B>Note:</B> If you are processing a ResultSet then any warnings + * associated with ResultSet reads will be chained on the ResultSet + * object. + * + * @return the first SQLWarning on null + * @exception SQLException if a database access error occurs + */ + public SQLWarning getWarnings() throws SQLException + { + return warnings; + } + + /** + * After this call, getWarnings returns null until a new warning + * is reported for this Statement. + * + * @exception SQLException if a database access error occurs (why?) + */ + public void clearWarnings() throws SQLException + { + warnings = null; + } + + /** + * setCursorName defines the SQL cursor name that will be used by + * subsequent execute methods. This name can then be used in SQL + * positioned update/delete statements to identify the current row + * in the ResultSet generated by this statement. If a database + * doesn't support positioned update/delete, this method is a + * no-op. + * + * <B>Note:</B> By definition, positioned update/delete execution + * must be done by a different Statement than the one which + * generated the ResultSet being used for positioning. Also, cursor + * names must be unique within a Connection. + * + * We throw an additional constriction. There can only be one + * cursor active at any one time. + * + * @param name the new cursor name + * @exception SQLException if a database access error occurs + */ + public void setCursorName(String name) throws SQLException + { + connection.setCursorName(name); + } + + /** + * Execute a SQL statement that may return multiple results. We + * don't have to worry about this since we do not support multiple + * ResultSets. You can use getResultSet or getUpdateCount to + * retrieve the result. + * + * @param sql any SQL statement + * @return true if the next result is a ResulSet, false if it is + * an update count or there are no more results + * @exception SQLException if a database access error occurs + */ + public boolean execute(String sql) throws SQLException + { + result = connection.ExecSQL(sql); + return (result != null && result.reallyResultSet()); + } + + /** + * getResultSet returns the current result as a ResultSet. It + * should only be called once per result. + * + * @return the current result set; null if there are no more + * @exception SQLException if a database access error occurs (why?) + */ + public java.sql.ResultSet getResultSet() throws SQLException + { + return result; + } + + /** + * getUpdateCount returns the current result as an update count, + * if the result is a ResultSet or there are no more results, -1 + * is returned. It should only be called once per result. + * + * @return the current result as an update count. + * @exception SQLException if a database access error occurs + */ + public int getUpdateCount() throws SQLException + { + if (result == null) return -1; + if (result.reallyResultSet()) return -1; + return result.getResultCount(); + } + + /** + * getMoreResults moves to a Statement's next result. If it returns + * true, this result is a ResulSet. + * + * @return true if the next ResultSet is valid + * @exception SQLException if a database access error occurs + */ + public boolean getMoreResults() throws SQLException + { + result = result.getNext(); + return (result != null && result.reallyResultSet()); + } +} |