DBKeySet


1   /*
2     Copyright (C) 2003  Know Gate S.L. All rights reserved.
3                         C/O�a, 107 1�2 28050 Madrid (Spain)
4   
5     Redistribution and use in source and binary forms, with or without
6     modification, are permitted provided that the following conditions
7     are met:
8   
9     1. Redistributions of source code must retain the above copyright
10       notice, this list of conditions and the following disclaimer.
11  
12    2. The end-user documentation included with the redistribution,
13       if any, must include the following acknowledgment:
14       "This product includes software parts from hipergate
15       (http://www.hipergate.org/)."
16       Alternately, this acknowledgment may appear in the software itself,
17       if and wherever such third-party acknowledgments normally appear.
18  
19    3. The name hipergate must not be used to endorse or promote products
20       derived from this software without prior written permission.
21       Products derived from this software may not be called hipergate,
22       nor may hipergate appear in their name, without prior written
23       permission.
24  
25    This library is distributed in the hope that it will be useful,
26    but WITHOUT ANY WARRANTY; without even the implied warranty of
27    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
28  
29    You should have received a copy of hipergate License with this code;
30    if not, visit http://www.hipergate.org or mail to info@hipergate.org
31  */
32  
33  package com.knowgate.dataobjs;
34  
35  import java.sql.SQLException  ;
36  import java.sql.PreparedStatement  ;
37  import java.sql.Statement  ;
38  import java.sql.ResultSet  ;
39  
40  import java.util.TreeSet  ;
41  
42  import com.knowgate.debug.DebugFile;
43  import com.knowgate.jdc.JDCConnection;
44  
45  /**
46   * Load a primary keys set from the database into a java.util.TreeSet
47   * @author Sergio Montoro Ten
48   * @version 1.0
49   */
50  
51  public class DBKeySet extends TreeSet   {
52    private String   sTable;
53    private String   sColumn;
54    private String   sWhere;
55    private int iMaxRows;
56  
57    /**
58     * @param sTableName Table Name
59     * @param sColumnName Column Name
60     * @param sWhereClause SQL WHERE clause
61     * @param iLimit Absolute maximum number of primary key to be loaded
62     */
63    public DBKeySet(String   sTableName, String   sColumnName, String   sWhereClause, int iLimit) {
64      sTable = sTableName;
65      sColumn = sColumnName;
66      sWhere = sWhereClause;
67      iMaxRows = (iLimit>0 ? iLimit : 2147483647);
68    }
69  
70    // ---------------------------------------------------------------------------
71  
72    private String   composeSQL(int iDbms, int iMaxRows) {
73      String   sSQL;
74      if (iMaxRows<2147483647) {
75        switch (iDbms) {
76          case JDCConnection.DBMS_MSSQL:
77            sSQL = "SELECT " + sColumn + " FROM " + sTable + " WHERE " + sWhere + " OPTION FAST (" + String.valueOf(iMaxRows) + ")";
78            break;
79          case JDCConnection.DBMS_MYSQL:
80            sSQL = "SELECT " + sColumn + " FROM " + sTable + " WHERE " + sWhere + " LIMIT 0," + String.valueOf(iMaxRows);
81            break;
82          case JDCConnection.DBMS_POSTGRESQL:
83            sSQL = "SELECT " + sColumn + " FROM " + sTable + " WHERE " + sWhere + " LIMIT " + String.valueOf(iMaxRows);
84            break;
85          case JDCConnection.DBMS_ORACLE:
86            sSQL = "SELECT " + sColumn + " FROM " + sTable + " WHERE ROWNUM<=" + String.valueOf(iMaxRows) + " AND " + sWhere;
87            break;
88          default:
89            sSQL = "SELECT " + sColumn + " FROM " + sTable + " WHERE " + sWhere;
90        }
91      }
92      else {
93        sSQL = "SELECT " + sColumn + " FROM " + sTable + " WHERE " + sWhere;
94      }
95      return sSQL;
96    }
97  
98    // ---------------------------------------------------------------------------
99  
100   /**
101    * Load primary keys from the database to this TreeSet
102    * @param oConn JDBC Database Connection
103    * @return Number of keys actually readed
104    * @throws SQLException
105    */
106   public int load (JDCConnection oConn) throws SQLException   {
107     String   sSQL = composeSQL(oConn.getDataBaseProduct(), iMaxRows);
108     Statement   oStmt = oConn.createStatement(ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
109     if (DebugFile.trace) DebugFile.writeln("Statement.eecuteQuery("+sSQL+")");
110     ResultSet   oRSet = oStmt.executeQuery(sSQL);
111     try { if (iMaxRows<2147483647) oRSet.setFetchSize(iMaxRows); else oRSet.setFetchSize(1000); } catch (SQLException   ignore) {}
112     clear();
113     int iReaded = 0;
114     while (oRSet.next()) {
115       add(oRSet.getObject(1));
116       iReaded++;
117     }
118     oRSet.close();
119     oStmt.close();
120     return iReaded;
121   }
122 
123   // ---------------------------------------------------------------------------
124 
125   /**
126    * Load primary keys from the database to this TreeSet
127    * @param oConn JDBC Database Connection
128    * @param aParams Parameters to be binded to prepared SQL
129    * @return Number of keys actually readed
130    * @throws SQLException
131    */
132   public int load (JDCConnection oConn, Object  [] aParams) throws SQLException   {
133     String   sSQL = composeSQL(oConn.getDataBaseProduct(), iMaxRows);
134     if (DebugFile.trace) DebugFile.writeln("Connection.prepareStatement("+sSQL+")");
135     PreparedStatement   oStmt = oConn.prepareStatement(sSQL, ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_READ_ONLY);
136     for (int p=0;p<aParams.length; p++)
137       oStmt.setObject(p+1, aParams[p]);
138     ResultSet   oRSet = oStmt.executeQuery();
139     try { if (iMaxRows<2147483647) oRSet.setFetchSize(iMaxRows); else oRSet.setFetchSize(1000); } catch (SQLException   ignore) {}
140     clear();
141     int iReaded = 0;
142     while (oRSet.next()) {
143       add(oRSet.getObject(1));
144       iReaded++;
145     }
146     oRSet.close();
147     oStmt.close();
148     return iReaded;
149   }
150 
151   // ---------------------------------------------------------------------------
152 
153   public int count(JDCConnection oConn) throws SQLException   {
154     Statement   oStmt = oConn.createStatement();
155     ResultSet   oRSet = oStmt.executeQuery("SELECT COUNT("+sColumn+") FROM "+sTable+" WHERE "+sWhere);
156     int iRetVal = oRSet.getInt(1);
157     oRSet.close();
158     oStmt.close();
159     return iRetVal;
160   }
161 
162   // ---------------------------------------------------------------------------
163 }
164
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