include/Table.h

   1 /***************************************************************************
   2  *   Copyright (C) 2007 by www.databasecache.com                           *
   3  *   Contact: praba_tuty@databasecache.com                                 *
   4  *                                                                         *
   5  *   This program is free software; you can redistribute it and/or modify  *
   6  *   it under the terms of the GNU General Public License as published by  *
   7  *   the Free Software Foundation; either version 2 of the License, or     *
   8  *   (at your option) any later version.                                   *
   9  *                                                                         *
  10  *   This program is distributed in the hope that it will be useful,       *
  11  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  12  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  13  *   GNU General Public License for more details.                          *
  14  *                                                                         *
  15   ***************************************************************************/
  16 #ifndef TABLE_H
  17 #define TABLE_H
  18 #include<ErrorType.h>
  19 class Predicate;
  20 class Condition;
  21 class FieldNameList;
  22 /**
  23 * @class Table
  24 *
  25 * @brief Handle to the database table.
  26 * Table is a set of data values organized using a model of horizontal rows and columns.<br>
  27 * Columns are identified by name and rows by values. It shall be visualized as a linked <br/>
  28 * list of related data<br/>
  29 * Functionality: <br/>
  30 *     1.insert <br/>
  31 *     2.update <br/>
  32 *     3.delete <br/>
  33 *     4.select with predicate or condition<br/>
  34 * <br/>
  35 * @author Prabakaran Thirumalai
  36 */
  37
  38 class FieldInfo;
  39 class Table
  40 {
  41     public:
  42     /** sets condition for the select, update and delete operations
  43     *   @param c condition
  44     */
  45     virtual void setCondition(Condition *c)=0;
  46
  47     /** binds application buffer to the specified field of the table.
  48     * Before doing any DML operations required fields are binded first.
  49     * Below are the candidates for this: <br/>
  50     * 1.All the fields in the projection list of select statement. <br/>
  51     * 2.Field list in the insert statement.<br/>
  52     * 3.Fields in the assignment list of update statement.<br/>
  53     * <br/>
  54     *   @param name field name in the table
  55     *   @param val  address of the application buffer. Memory should be allocated by
  56     *               the application before binding the buffer.
  57     */
  58
  59     virtual void bindFld(const char *name, void *val)=0;
  60     /** marks the specified field to insert null when insert method is called.
  61     *   @param name field name in the table
  62     */
  63
  64     virtual void markFldNull(const char *name)=0;
  65     /** marks the specified field to insert null when insert method is called.
  66     *   @param colpos field position
  67     */
  68
  69     virtual void markFldNull(int colpos)=0;
  70
  71     /** checks whether the field value is null.
  72     *   @param name field name
  73     */
  74     virtual bool isFldNull(const char *name)=0;
  75
  76     /** checks whether the field value is null for the specified field position.
  77     *   @param colpos field position
  78     */
  79     virtual bool isFldNull(int colpos)=0;
  80 /*
  81     virtual void clearFldNull(const char *name)=0;
  82     virtual void clearFldNull(int colpos) =0;
  83 */
  84
  85     //DML operations
  86     /** executes the select statement. Based on the predicate(condition), respective index is
  87     * chosen for the select. Application should call execute before they start fetching
  88     * the values from the table.This starts scan on the table.
  89     * @returns DbRetVal
  90     */
  91     virtual DbRetVal execute()=0;
  92
  93     /** insert the tuple into the table. Prior to this, the binded buffer should be updated
  94     *  Values present in the binded buffers of all the fields are taken and stored in
  95     *  the table.<br/>
  96     * @returns DbRetVal
  97     */
  98     virtual DbRetVal insertTuple()=0;
  99
 100     /**update values in the current tuple of the table. It works only on top of select
 101     *  using fetch go to the tuple to be updated, then update the binded buffer value and
 102     *  then call this method to updates the field values in the tuple.
 103     * @returns DbRetVal
 104     */
 105     virtual DbRetVal updateTuple()=0;
 106
 107     /**deletes the current tuple of the table. It works only on top of select.
 108     *  using fetch first go to the tuple to be deleted, then call this method to delete.<br/>
 109     *  To delete all the tuples, do not set any condition and call fetch followed by delete
 110     *  in a loop till fetch exhausts.
 111     * @returns DbRetVal
 112     */
 113
 114     virtual DbRetVal deleteTuple()=0;
 115
 116     //scan
 117
 118     /**fetches the next tuple in the table which satisfies the condition specified.
 119     * execute should be called before calling this method. Application buffer should be
 120     * binded to get the tuple values.
 121     * @returns void* NULL if there is no tuple.
 122     */
 123     virtual void* fetch()=0;
 124
 125     /**fetches the next tuple in the table which satisfies the condition specified.
 126     * execute should be called before calling this method. Application buffer need not be
 127     * binded to call this method.
 128     * @returns void* NULL if there is no tuple.
 129     */
 130     virtual void* fetchNoBind()=0;
 131
 132
 133     /**closes the scan. Needs to be called before calling execute again on the same table handle. It releases the resources
 134  acquired during the scan.
 135     * @returns DbRetVal
 136     */
 137
 138     virtual DbRetVal close()=0;
 139
 140     /**Retrieves the total space used for this table in bytes
 141     * @returns DbRetVal
 142     */
 143     virtual long spaceUsed()=0;
 144
 145     /**Retrieves the total number of tuples present in this table
 146     * @returns DbRetVal
 147     */
 148     virtual long numTuples()=0;
 149
 150
 151     virtual DbRetVal getFieldInfo(const char *fieldName, FieldInfo *&info)=0;
 152     virtual FieldNameList getFieldNameList()=0;
 153
 154     virtual ~Table() { }
 155 };
 156 #endif