KDb

KDbQueryAsterisk.h
1/* This file is part of the KDE project
2 Copyright (C) 2003-2017 Jarosław Staniek <staniek@kde.org>
3
4 This library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Library General Public
6 License as published by the Free Software Foundation; either
7 version 2 of the License, or (at your option) any later version.
8
9 This library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Library General Public License for more details.
13
14 You should have received a copy of the GNU Library General Public License
15 along with this library; see the file COPYING.LIB. If not, write to
16 the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
17 * Boston, MA 02110-1301, USA.
18*/
19
20#ifndef KDB_QUERYASTERISK_H
21#define KDB_QUERYASTERISK_H
22
23#include "KDbField.h"
24
25class KDbQuerySchema;
26
27//! @short KDbQueryAsterisk class encapsulates information about single asterisk in query definition
28/*! There are two types of query asterisks:
29
30 1. "Single-table" asterisk, that references all fields of given table used
31 in the query.
32 Example SQL statement:
33 @code
34 SELECT staff.*, cars.model from staff, cars WHERE staff.car = cars.number;
35 @endcode
36 The "staff.*" element is our "single-table" asterisk;
37 this tells us that we want to get all fields of table "staff".
38
39 2. "All-tables" asterisk, that references all fields of all tables used in the query.
40 Example SQL statement:
41 @code
42 SELECT * from staff, cars WHERE staff.car = cars.number;
43 @endcode
44 The "*" is our "all-tables" asterisk;
45 this tells us that we want to get all fields of all used tables (here: "staff" and "cars").
46
47 There can be many asterisks of 1st type defined for given single query.
48 There can be one asterisk of 2nd type defined for given single query.
49*/
50class KDB_EXPORT KDbQueryAsterisk : public KDbField
51{
52public:
53 /*! Constructs an "all-tables" query asterisk definition object ("*" in SQL notation).
54
55 KDbQueryAsterisk objects are owned by KDbQuerySchema object
56 (not by KDbTableSchema object like for ordinary KDbField objects)
57 for that the KDbQueryAsterisk object was added (using KDbQuerySchema::addField()). */
58 explicit KDbQueryAsterisk(KDbQuerySchema *query);
59
60 /*! Constructs a "single-table" query asterisk definition object ("T.*" in SQL notation).
61 @a table schema is the single table for the asterisk.
62
63 KDbQueryAsterisk objects are owned by KDbQuerySchema object
64 (not by KDbTableSchema object like for ordinary KDbField objects)
65 for that the KDbQueryAsterisk object was added (using KDbQuerySchema::addField()). */
67
68 /*! Constructs a deep copy of query asterisk definition object @a asterisk. */
69 KDbQueryAsterisk(const KDbQueryAsterisk &asterisk);
70
71 ~KDbQueryAsterisk() override;
72
73 /**
74 * @brief Returns @c true if this query asterisk is equal to @a other
75 *
76 * @return @c false if the objects are not equal.
77 * Two asterisks are equal if they return the same table() and query().
78 * This also means that both return the same value for isSingleTableAsterisk() and
79 * isAllTableAsterisk().
80 *
81 * @since 3.1
82 */
83 bool operator==(const KDbQueryAsterisk& other) const;
84
85 /**
86 * @brief Returns @c true if this query asterisk is not equal to @a other
87 *
88 * @return @c false if objects are equal.
89 *
90 * @see operator==(const KDbQueryAsterisk&)
91 * @since 3.1
92 */
93 inline bool operator!=(const KDbQueryAsterisk &other) const { return !operator==(other); }
94
95 /*! @return Query object for that this asterisk object is defined */
97
98 /*! @overload KDbQuerySchema *query() */
99 const KDbQuerySchema *query() const;
100
101 /*! @return table schema object for that this asterisk object is defined.
102 If this is a "all-tables" asterisk, @c nullptr is returned. */
103 const KDbTableSchema* table() const;
104
105 /*! Sets table schema for this asterisk.
106 If table is supplied, the asterisk become a "single-table" asterisk.
107 If @a table is @c nullptr the asterisk becames "all-tables" asterisk. */
108 void setTable(const KDbTableSchema *table);
109
110 /*! This is convenience method that returns @c true
111 if the asterisk has "all-tables" type (2nd type).*/
112 bool isSingleTableAsterisk() const;
113
114 /*! This is convenience method that returns @c true
115 if the asterisk has "single-table" type (2nd type).*/
116 bool isAllTableAsterisk() const;
117
118protected:
119 //! @return a deep copy of this object. Used in KDbFieldList(const KDbFieldList& fl).
120 KDbField* copy() override;
121
122 KDbQueryAsterisk(KDbQuerySchema *query, const KDbTableSchema *table);
123
124private:
125 class Private;
126 Private * const d;
127 KDbQueryAsterisk& operator=(const KDbQueryAsterisk &) = delete;
128 void setTable(KDbTableSchema *table); // protect
129};
130
131//! Sends query asterisk information @a asterisk to debug output @a dbg.
132KDB_EXPORT QDebug operator<<(QDebug dbg, const KDbQueryAsterisk& asterisk);
133
134#endif
Meta-data for a field.
Definition KDbField.h:72
KDbTableSchema * table()
Definition KDbField.cpp:585
virtual KDbField * copy()
Definition KDbField.cpp:374
KDbQuerySchema * query()
Definition KDbField.cpp:600
void setTable(KDbTableSchema *table)
Definition KDbField.cpp:595
KDbQueryAsterisk class encapsulates information about single asterisk in query definition.
bool operator!=(const KDbQueryAsterisk &other) const
Returns true if this query asterisk is not equal to other.
KDbQuerySchema provides information about database query.
KTEXTEDITOR_EXPORT QDebug operator<<(QDebug s, const MovingCursor &cursor)
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