Quadcap Embeddable Database

com/quadcap/sql/UpdateItem.java

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package com.quadcap.sql;

/* Copyright 1999 - 2003 Quadcap Software.  All rights reserved.
 *
 * This software is distributed under the Quadcap Free Software License.
 * This software may be used or modified for any purpose, personal or
 * commercial.  Open Source redistributions are permitted.  Commercial
 * redistribution of larger works derived from, or works which bundle
 * this software requires a "Commercial Redistribution License"; see
 * http://www.quadcap.com/purchase.
 *
 * Redistributions qualify as "Open Source" under  one of the following terms:
 *   
 *    Redistributions are made at no charge beyond the reasonable cost of
 *    materials and delivery.
 *
 *    Redistributions are accompanied by a copy of the Source Code or by an
 *    irrevocable offer to provide a copy of the Source Code for up to three
 *    years at the cost of materials and delivery.  Such redistributions
 *    must allow further use, modification, and redistribution of the Source
 *    Code under substantially the same terms as this license.
 *
 * Redistributions of source code must retain the copyright notices as they
 * appear in each source code file, these license terms, and the
 * disclaimer/limitation of liability set forth as paragraph 6 below.
 *
 * Redistributions in binary form must reproduce this Copyright Notice,
 * these license terms, and the disclaimer/limitation of liability set
 * forth as paragraph 6 below, in the documentation and/or other materials
 * provided with the distribution.
 *
 * The Software is provided on an "AS IS" basis.  No warranty is
 * provided that the Software is free of defects, or fit for a
 * particular purpose.  
 *
 * Limitation of Liability. Quadcap Software shall not be liable
 * for any damages suffered by the Licensee or any third party resulting
 * from use of the Software.
 */

import java.io.IOException;

import java.sql.SQLException;

import com.quadcap.sql.types.Value;
import com.quadcap.sql.types.ValueDefault;

import com.quadcap.util.Debug;

/**
 * One part of a compiled <b>UPDATE</b> statement, including a column name and
 * an expression which generates a value.
 *
 * @author Stan Bailes
 */
public class UpdateItem {
    String                      name;
    Expression                  e;
    Value                       v;
    int                         col             = -1;

    public UpdateItem(String name, Expression e) {
        this.name = name;
        this.e = e;
    }

    void evaluate(Session session, Relation r, Cursor cursor)
        throws SQLException, IOException
    {
        if (col < 0) {
            Column c = cursor.getColumn(name);
            if (c == null) {
                throw new SQLException("Bad column: " + name, "42000");
            }
            col = c.getColumn();
        }
        v = e.getValue(session, cursor);
        if (v instanceof ValueDefault) {
            Column c = r.getColumn(col);
            Expression ex = c.getDefault();
            if (ex != null) {
                v = ex.getValue(session, cursor);
            }
        }
    }

    public void update(Session session, Row row)
        throws SQLException, IOException
    {
        row.set(col, v);
    }
}