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Java > Open Source Codes > com > quadcap > sql > TableExpression


1 package com.quadcap.sql;
2
3 /* Copyright 1999 - 2003 Quadcap Software. All rights reserved.
4  *
5  * This software is distributed under the Quadcap Free Software License.
6  * This software may be used or modified for any purpose, personal or
7  * commercial. Open Source redistributions are permitted. Commercial
8  * redistribution of larger works derived from, or works which bundle
9  * this software requires a "Commercial Redistribution License"; see
10  * http://www.quadcap.com/purchase.
11  *
12  * Redistributions qualify as "Open Source" under one of the following terms:
13  *
14  * Redistributions are made at no charge beyond the reasonable cost of
15  * materials and delivery.
16  *
17  * Redistributions are accompanied by a copy of the Source Code or by an
18  * irrevocable offer to provide a copy of the Source Code for up to three
19  * years at the cost of materials and delivery. Such redistributions
20  * must allow further use, modification, and redistribution of the Source
21  * Code under substantially the same terms as this license.
22  *
23  * Redistributions of source code must retain the copyright notices as they
24  * appear in each source code file, these license terms, and the
25  * disclaimer/limitation of liability set forth as paragraph 6 below.
26  *
27  * Redistributions in binary form must reproduce this Copyright Notice,
28  * these license terms, and the disclaimer/limitation of liability set
29  * forth as paragraph 6 below, in the documentation and/or other materials
30  * provided with the distribution.
31  *
32  * The Software is provided on an "AS IS" basis. No warranty is
33  * provided that the Software is free of defects, or fit for a
34  * particular purpose.
35  *
36  * Limitation of Liability. Quadcap Software shall not be liable
37  * for any damages suffered by the Licensee or any third party resulting
38  * from use of the Software.
39  */
40
41 import com.quadcap.sql.types.Type;
42 import com.quadcap.sql.types.TypeAny;
43
44 import java.util.Vector JavaDoc;
45
46 import java.sql.SQLException JavaDoc;
47
48 /**
49  * Some kind of expression that yields a 'table', which can be joined or
50  * merged or cursored.
51  *
52  * @author Stan Bailes
53  */
54 public abstract class TableExpression extends Expression {
55     boolean anded = false;
56     Expression where = null;
57     
58     /**
59      * Returns zero if this is a scalar expression, one if it's a vector
60      * type and 2 if it's a table/cursor type.
61      */
62     public abstract int rank();
63
64     /**
65      * Is this table expression updatable?
66      */
67     public abstract boolean isUpdatable();
68
69     /**
70      * Return a cursor which can be used to access this table expression.
71      */
72     public abstract Cursor getCursor(Session session, Cursor outer)
73         throws SQLException JavaDoc;
74
75     public Type getType(Session session, Cursor cursor) {
76         return TypeAny.any;
77     }
78     
79     /**
80      * Return a vector consisting of the names of the underlying base tables
81      * that are used to derive this table expression.
82      */
83     public abstract void getBaseTables(Vector JavaDoc v);
84
85     /**
86      * Set the WHERE clause associated with this table expression.
87      */
88     public void setWhere(Expression where) { this.where = where; }
89
90     /**
91      * Return the WHERE clause associated with this table expression.
92      */
93     public Expression getWhere() { return where; }
94
95     //#ifdef DEBUG
96 public abstract String JavaDoc name();
97     //#endif
98 }
99
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