view.java

来自「一个用java写的开源的数据库系统」· Java 代码 · 共 108 行

/* Copyright (c) 2001-2002, The HSQL Development Group
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 
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 */


package org.hsqldb;

import java.sql.SQLException;

// fredt@users 20020420 - patch523880 by leptipre@users - VIEW support - modified

/**
 * Implementation of SQL VIEWS based on a SELECT query.
 *
 * @author leptipre@users
 * @version 1.7.0
 */
class View extends Table {

    String sStatement;

    View(Database db, HsqlName name) throws SQLException {

        super(db, name, VIEW, null);

        sStatement = "";
    }

    void addColumns(Result result) throws SQLException {

        for (int i = 0; i < result.getColumnCount(); i++) {
            String name = result.sTable[i];
            Table  t    = dDatabase.findUserTable(name);

            if (t != null && t.isTemp()) {
                throw Trace.error(Trace.TABLE_NOT_FOUND);
            }

            if (result.sLabel[i] == null) {

                // fredt - this does not guarantee the uniqueness of column
                // names but addColumns() will throw if names are not unique.
                result.sLabel[i] = "COL_" + String.valueOf(i);
            }
        }

        super.addColumns(result);

        iVisibleColumns = iColumnCount;
    }

    /**
     * Tokenize the SELECT statement to get rid of any comment line that
     * may exist at the end. Store the result
     * for performing selects and logging the DDL at checkpoints.
     *
     * @param s
     *
     * @throws SQLException
     */
    void setStatement(String s) throws SQLException {

        int       position;
        String    str;
        Tokenizer t = new Tokenizer(s);

        // fredt@users - this establishes the end of the actual statement
        // to get rid of any end semicolon or comment line after the end
        // of statement
        do {
            position = t.getPosition();
            str      = t.getString();
        } while (str.length() != 0 || t.wasValue());

        sStatement = s.substring(0, position);
    }

    String getStatement() throws SQLException {
        return sStatement;
    }
}