_SelectIterator


1   package com.daffodilwoods.daffodildb.server.sql99.dql.listenerevents;
2   
3   import com.daffodilwoods.daffodildb.client.*;
4   import com.daffodilwoods.daffodildb.server.datadictionarysystem.*;
5   import com.daffodilwoods.daffodildb.server.sql99.common.*;
6   import com.daffodilwoods.daffodildb.server.sql99.dql.resultsetmetadata.*;
7   import com.daffodilwoods.database.resource.*;
8   import com.daffodilwoods.daffodildb.client._BrowserPlan;
9   
10  /**
11   * It provides full control of select query viz fetching of data, medium to
12   * understand the data returned, information about the selected columns of the
13   * query, modification through resultset.
14   * <p>Title: </p>
15   * <p>Description: </p>
16   * <p>Copyright: Copyright (c) 2003</p>
17   * <p>Company: </p>
18   * @author unascribed
19   * @version 1.0
20   */
21  
22  public interface _SelectIterator extends _BrowserPlan{
23  
24     /**
25      * It is used to get all the information about the columns present in
26      * select list of the query.
27      * @return ColumnCharacteristics
28      * @throws DException
29      */
30  
31     _ColumnCharacteristics getColumnCharacteristics() throws DException;
32  
33     /**
34      * It is used to read the row returned by select query. It is returned
35      * based on the type of ResultSet. It can be any of SCROLLABLE, NONSCROLLABLE
36      * and UPDTABLE.
37      * @return RowReader
38      * @throws DException
39      */
40  
41     _RowReader getRowReader() throws DException;
42  
43     /**
44      * This method moves the pointer to just before the first row. It is required
45      * before the start of fetching rows in forward direction.
46      * @throws DException
47      */
48  
49     void beforeFirst() throws DException;
50  
51     /**
52      * It is required to fetch the passed number of rows from the i + 1  position
53      *  in forward direction, where i is the position where pointer was aligned
54      * previously. If pointer is aligned at BEFOREFIRST position then this method
55      * will return starting as many rows as equivalent to p ssed rowCount. If
56      * there are lesser number of rows present in resultset as compare to
57      * rowCount, then that many rows are returned.
58      * @param rowCount is maximum number of rows to be fetched.
59      * @return array of rows
60      * @throws DException
61      */
62  
63     Object  [] fetchForward(int rowCount) throws DException;
64  
65     /**
66      * This method moves the pointer to just after the last row. It is required
67      * before the start of fetching rows in backward direction.
68      * @throws DException
69      */
70  
71     void afterLast() throws DException;
72  
73     /**
74      * It is required to fetch the passed number of rows from the i - 1  position
75      * in the backward direction, where i is the position where pointer was
76      * aligned previously. If pointer is aligned at AFTERLAST position then this
77      * method will return last as many rows as equivalent to passed rowCount. If
78      * there are lesser number of rows present in resultset as compare to
79      * rowCount, then that many rows are returned.
80      * @param rowCount is maximum number of rows to be fetched.
81      * @return array of rows
82      * @throws DException
83      */
84  
85     Object  [] fetchBackward(int rowCount) throws DException;
86  
87     /**
88      * It allows user to move the pointer on the row denoting by the key passed.
89      * Each row is uniquely denoted by key.
90      * @param key
91      * @usage RecordSetBuffer
92      * @throws DException
93      */
94  
95     void moveToRow(Object   key) throws DException;
96  
97     /**
98      * It allows the user to move the current pointer to i + rowCount when
99      * rowCount is positive or i - rowCount when rowCount is negative where i is
100     * the current pointer position. If there are lesser number of rows present
101     * in resultset as compare to rowCount, then that many rows are returned.
102     * @param rowCount
103     * @return
104     * @throws DException
105     */
106 
107    int move(int rowCount) throws DException;
108 
109    /**
110     * It is required to retrieve info related to data modifications through
111     * resultset.
112     * @return SelectColumnCharacteristics
113     * @throws DException
114     */
115 
116    _SelectColumnCharacteristics getSelectColumnCharacteristics() throws DException;
117 
118    /**
119     * It returns the number of rows present in the result set taken on select
120     * query.
121     * @return
122     * @throws DException
123     */
124 
125    int getRowCount()  throws DException;
126 
127    /**
128     * This method inserts a row in the resultset with the passed value at the
129     * corresponding places indicated by column indexes. Insertion is supported
130     * on the resultset taken on single table select query.
131     * @param columnIndexes
132     * @param columnValues
133     * @return key of newly inserted row.
134     * @throws DException
135     */
136 
137    Object   insert(int[] columnIndexes,Object  [] columnValues)  throws DException; // will return rowReader.getKey()
138 
139    /**
140     * This method updates a row denoted by the passed key. The row is updated
141     * for the columns indicated by the column indexes with the passed values.
142     * Updation is supported on the resultset taken on single table select query.
143     * @param key
144     * @param columnIndexes
145     * @param values
146     * @param row
147     * @return key of the updated row.
148     * @throws DException
149     */
150 
151    Object   update(Object   key,int[] columnIndexes,Object  [] values,Object   row)  throws DException ; // here key will be rowReader key and return object will also be rowReaderKey.
152 
153    /**
154     * This method deletes a row denoted by the passed key. Deletion is supported
155     * on the resultset taken on single table select query.
156     * @param key denoting the row
157     * @throws DException
158     */
159 
160    void delete(Object   key)  throws DException ; // key will be recordReaderKey
161 
162    /**
163     * This method is required when user presses insert button on the GUI to
164     * insert a row. Then a blank row is inserted on the resultset taken on
165     * single table select query.
166     * @return key of newly inserted blank row
167     * @usage RecordSetBuffer
168     * @throws DException
169     */
170 
171    Object   moveToInsertRow() throws DException;
172 
173    /**
174     * This method is required when user doesn't want to save the newly inserted
175     * blank row.
176     * @usage RecordSetBuffer
177     * @throws DException
178     */
179 
180    void flushInsertedRecord() throws DException ;
181 
182    /**
183     * This method is required to display the plan choosen for execution of the
184     * select query.
185     * @return QueryPlan
186     * @usage DaffodilDBBrowser
187     * @throws DException
188     */
189 
190    _QueryPlan getQueryPlan() throws DException;
191 
192    /**
193     * It is required to get the values of only selected columns when the result
194     * set is of UPDATABLE type. When resultset is updatable then whole row is
195     * returned so in that case, this method helps in retrieving values of
196     * selected columns.
197     * @return
198     * @throws DException
199     */
200 
201    Object   getSelectColumnValues() throws DException;
202 
203    /**
204     * It is required to get the appropriate row  based on the resultset type. If
205     * resultset is UPDATABLE then whole row is returned otherwise row consisting
206     * of the value of selected columns is returned.
207     * @return row
208     * @throws DException
209     */
210 
211    Object   getObject() throws DException;
212 
213    /**
214     * It is required to know whether select query supports the updatable type of
215     * resultset. Select query of only single table without groupby, functional
216     * columns is candidate of updatable type.
217     * @return
218     * @usage ServerSession
219     * @throws DException
220     */
221 
222    boolean isUpdatable() throws DException;
223 
224    /**
225     * It is required to get the datatypes of selected columns present in select
226     * query
227     * @return data types of selected columns.
228     * @throws DException
229     */
230 
231    int[] getDataTypes() throws DException;
232 }
233
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