jtdsdatabasemetadata.java

jtds的源码 是你学习java的好东西

     *        whether unique or not
     * @param approximate when <code>true</code>, result is allowed to reflect
     *        approximate or out of data values; when <code>false</code>, results
     *        are requested to be accurate
     * @return ResultSet - each row is an index column description
     * @throws SQLException if a database-access error occurs.
     */
    public java.sql.ResultSet getIndexInfo(String catalog,
                                           String schema,
                                           String table,
                                           boolean unique,
                                           boolean approximate)
    throws SQLException {
        String colNames[] = {"TABLE_CAT",       "TABLE_SCHEM",
                             "TABLE_NAME",      "NON_UNIQUE",
                             "INDEX_QUALIFIER", "INDEX_NAME",
                             "TYPE",            "ORDINAL_POSITION",
                             "COLUMN_NAME",     "ASC_OR_DESC",
                             "CARDINALITY",     "PAGES",
                             "FILTER_CONDITION"};
        int    colTypes[] = {Types.VARCHAR,     Types.VARCHAR,
                             Types.VARCHAR,     Types.BIT,
                             Types.VARCHAR,     Types.VARCHAR,
                             Types.SMALLINT,    Types.SMALLINT,
                             Types.VARCHAR,     Types.VARCHAR,
                             Types.INTEGER,     Types.INTEGER,
                             Types.VARCHAR};
        String query = "sp_statistics ?, ?, ?, ?, ?, ?";

        CallableStatement s = connection.prepareCall(syscall(catalog, query));

        s.setString(1, table);
        s.setString(2, schema);
        s.setString(3, catalog);
        s.setString(4, "%");
        s.setString(5, unique ? "Y" : "N");
        s.setString(6, approximate ? "Q" : "E");

        JtdsResultSet rs = (JtdsResultSet) s.executeQuery();
        int colCnt = rs.getMetaData().getColumnCount();
        CachedResultSet rsTmp = new CachedResultSet((JtdsStatement)s, colNames, colTypes);
        rsTmp.moveToInsertRow();
        while (rs.next()) {
            for (int i = 1; i <= colCnt; i++) {
                rsTmp.updateObject(i, rs.getObject(i));
            }
            rsTmp.insertRow();
        }
        rs.close();
        rsTmp.moveToCurrentRow();
        rsTmp.setConcurrency(ResultSet.CONCUR_READ_ONLY);

        return rsTmp;
    }

    //----------------------------------------------------------------------
    // The following group of methods exposes various limitations
    // based on the target database with the current driver.
    // Unless otherwise specified, a result of zero means there is no
    // limit, or the limit is not known.

    /**
     * How many hex characters can you have in an inline binary literal?
     *
     * @return max literal length
     * @throws SQLException if a database-access error occurs.
     */
    public int getMaxBinaryLiteralLength() throws SQLException {
        // Sybase jConnect says 255
        // Actual value is 16384 for Sybase 12.5
        // MS JDBC says 0
        // Probable maximum size for MS is 65,536 * network packet size
        return 131072;
        // per "Programming ODBC for SQLServer" Appendix A
    }

    /**
     * What's the maximum length of a catalog name?
     *
     * @return max name length in bytes
     * @throws SQLException if a database-access error occurs.
     */
    public int getMaxCatalogNameLength() throws SQLException {
        return sysnameLength;
    }

    /**
     * What's the max length for a character literal?
     *
     * @return max literal length
     * @throws SQLException if a database-access error occurs.
     */
    public int getMaxCharLiteralLength() throws SQLException {
        // Sybase jConnect says 255
        // Actual value is 16384 for Sybase 12.5
        // MS JDBC says 0
        // Probable maximum size for MS is 65,536 * network packet size
        return 131072;
        // per "Programming ODBC for SQLServer" Appendix A
    }

    /**
     * What's the limit on column name length?
     *
     * @return max literal length
     * @throws SQLException if a database-access error occurs.
     */
    public int getMaxColumnNameLength() throws SQLException {
        // per "Programming ODBC for SQLServer" Appendix A
        return sysnameLength;
    }

    /**
     * What's the maximum number of columns in a "GROUP BY" clause?
     *
     * @return max number of columns
     * @throws SQLException if a database-access error occurs.
     */
    public int getMaxColumnsInGroupBy() throws SQLException {
        // Sybase jConnect says 16
        // MS JDBC says 16
        // per "Programming ODBC for SQLServer" Appendix A
        // Actual MS value is 8060 / average bytes per column
        return (tdsVersion >= Driver.TDS70) ? 0 : 16;
    }

    /**
     * What's the maximum number of columns allowed in an index?
     *
     * @return max columns
     * @throws SQLException if a database-access error occurs.
     */
    public int getMaxColumnsInIndex() throws SQLException {
        // per SQL Server Books Online "Administrator's Companion",
        // Part 1, Chapter 1.
        // Sybase 12.5 is 31
        return 16;
    }

    /**
     * What's the maximum number of columns in an "ORDER BY" clause?
     *
     * @return max columns
     * @throws SQLException if a database-access error occurs.
     */
    public int getMaxColumnsInOrderBy() throws SQLException {
        // per "Programming ODBC for SQLServer" Appendix A
        // Sybase 12.5 is 31
        // Actual MS value is 8060 / average bytes per column
        return (tdsVersion >= Driver.TDS70) ? 0 : 16;
    }

    /**
     * What's the maximum number of columns in a "SELECT" list?
     *
     * @return max columns
     * @throws SQLException if a database-access error occurs.
     */
    public int getMaxColumnsInSelect() throws SQLException {
        // Sybase jConnect says 0
        // per "Programming ODBC for SQLServer" Appendix A
        return 4096;
    }

    /**
     * What's the maximum number of columns in a table?
     *
     * @return max columns
     * @throws SQLException if a database-access error occurs.
     */
    public int getMaxColumnsInTable() throws SQLException {
        // Sybase jConnect says 250
        // per "Programming ODBC for SQLServer" Appendix A
        // MS 2000 should be 4096
        // Sybase 12.5 is now 1024
        return (tdsVersion >= Driver.TDS70) ? 1024 : 250;
    }

    /**
     * How many active connections can we have at a time to this database?
     *
     * @return max connections
     * @throws SQLException if a database-access error occurs.
     */
    public int getMaxConnections() throws SQLException {
        // Sybase - could query syscurconfigs to get actual value
        // which in practice will be a lot less than 32767!
        // per SQL Server Books Online "Administrator's Companion",
        // Part 1, Chapter 1.
        return 32767;
    }

    /**
     * What's the maximum cursor name length?
     *
     * @return max cursor name length in bytes
     * @throws SQLException if a database-access error occurs.
     */
    public int getMaxCursorNameLength() throws SQLException {
        // per "Programming ODBC for SQLServer" Appendix A
        return sysnameLength;
    }

    /**
     * What's the maximum length of an index (in bytes)?
     *
     * @return max index length in bytes
     * @throws SQLException if a database-access error occurs.
     */
    public int getMaxIndexLength() throws SQLException {
        // Sybase JConnect says 255
        // Actual Sybase 12.5 is 600 - 5300 depending on page size
        // per "Programming ODBC for SQLServer" Appendix A
        return (tdsVersion >= Driver.TDS70) ? 900 : 255;
    }

    /**
     * What's the maximum length of a procedure name?
     *
     * @return max name length in bytes
     * @throws SQLException if a database-access error occurs.
     */
    public int getMaxProcedureNameLength() throws SQLException {
        // per "Programming ODBC for SQLServer" Appendix A
        return sysnameLength;
    }

    /**
     * What's the maximum length of a single row?
     *
     * @return max row size in bytes
     * @throws SQLException if a database-access error occurs.
     */
    public int getMaxRowSize() throws SQLException {
        // Sybase jConnect says 1962 but this can be more with wide tables.
        // per SQL Server Books Online "Administrator's Companion",
        // Part 1, Chapter 1.
        return (tdsVersion >= Driver.TDS70) ? 8060 : 1962;
    }

    /**
     * What's the maximum length allowed for a schema name?
     *
     * @return max name length in bytes
     * @throws SQLException if a database-access error occurs.
     */
    public int getMaxSchemaNameLength() throws SQLException {
        return sysnameLength;
    }

    /**
     * What's the maximum length of a SQL statement?
     *
     * @return max length in bytes
     * @throws SQLException if a database-access error occurs.
     */
    public int getMaxStatementLength() throws SQLException {
        // I think this should return 0 (no limit)
        // actual limit for SQL 7/2000 is 65536 * packet size!
        // Sybase JConnect says 0
        // MS JDBC says 0
        // per "Programming ODBC for SQLServer" Appendix A
        return 0;
    }

    /**
     * How many active statements can we have open at one time to this
     * database?
     *
     * @return the maximum
     * @throws SQLException if a database-access error occurs.
     */
    public int getMaxStatements() throws SQLException {
        return 0;
    }

    /**
     * What's the maximum length of a table name?
     *
     * @return max name length in bytes
     * @throws SQLException if a database-access error occurs.
     */
    public int getMaxTableNameLength() throws SQLException {
        // per "Programming ODBC for SQLServer" Appendix A
        return sysnameLength;
    }

    /**
     * What's the maximum number of tables in a SELECT?
     *
     * @return the maximum
     * @throws SQLException if a database-access error occurs.
     */
    public int getMaxTablesInSelect() throws SQLException {
        // Sybase JConnect says 256
        // MS JDBC says 32!
        // Actual Sybase 12.5 is 50
        // per "Programming ODBC for SQLServer" Appendix A
        return (tdsVersion > Driver.TDS50) ? 256 : 16;
    }

    /**
     *   What's the maximum length of a user name?
     *
     * @return max name length in bytes
     * @throws SQLException if a database-access error occurs.
     */
    public int getMaxUserNameLength() throws SQLException {
        return sysnameLength;