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Java > Open Source Codes > org > apache > torque > adapter > DBSybase


1 package org.apache.torque.adapter;
2
3 /*
4  * Licensed to the Apache Software Foundation (ASF) under one
5  * or more contributor license agreements. See the NOTICE file
6  * distributed with this work for additional information
7  * regarding copyright ownership. The ASF licenses this file
8  * to you under the Apache License, Version 2.0 (the
9  * "License"); you may not use this file except in compliance
10  * with the License. You may obtain a copy of the License at
11  *
12  * http://www.apache.org/licenses/LICENSE-2.0
13  *
14  * Unless required by applicable law or agreed to in writing,
15  * software distributed under the License is distributed on an
16  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17  * KIND, either express or implied. See the License for the
18  * specific language governing permissions and limitations
19  * under the License.
20  */
21
22 import java.sql.Connection JavaDoc;
23 import java.sql.SQLException JavaDoc;
24 import java.sql.Statement JavaDoc;
25 import java.text.SimpleDateFormat JavaDoc;
26 import java.util.Date JavaDoc;
27
28 import org.apache.torque.TorqueException;
29 import org.apache.torque.util.Criteria;
30 import org.apache.torque.util.Query;
31 import org.apache.torque.util.SqlExpression;
32
33 /**
34  * This is used to connect to a Sybase database using Sybase's
35  * JConnect JDBC driver.
36  *
37  * <B>NOTE:</B><I>Currently JConnect does not implement the required
38  * methods for ResultSetMetaData, and therefore the village API's may
39  * not function. For connection pooling, everything works.</I>
40  *
41  * @author <a HREF="mailto:ekkerbj@netscape.net">Jeff Brekke</a>
42  * @version $Id: DBSybase.java 476490 2006-11-18 11:38:04Z tfischer $
43  */
44 public class DBSybase extends AbstractDBAdapter
45 {
46     /**
47      * Serial version
48      */
49     private static final long serialVersionUID = 4782996646843056810L;
50
51     /** date format */
52     private static final String JavaDoc DATE_FORMAT = "yyyyMMdd HH:mm:ss";
53
54     /**
55      * Empty constructor.
56      */
57     protected DBSybase()
58     {
59     }
60
61     /**
62      * This method is used to ignore case.
63      *
64      * @param in The string to transform to upper case.
65      * @return The upper case string.
66      */
67     public String JavaDoc toUpperCase(String JavaDoc in)
68     {
69         return new StringBuffer JavaDoc("UPPER(").append(in).append(")").toString();
70     }
71
72     /**
73      * This method is used to ignore case.
74      *
75      * @param in The string whose case to ignore.
76      * @return The string in a case that can be ignored.
77      */
78     public String JavaDoc ignoreCase(String JavaDoc in)
79     {
80         return new StringBuffer JavaDoc("UPPER(").append(in).append(")").toString();
81     }
82
83     /**
84      * @see org.apache.torque.adapter.DB#getIDMethodType()
85      */
86     public String JavaDoc getIDMethodType()
87     {
88         return AUTO_INCREMENT;
89     }
90
91     /**
92      * Returns the last value from an identity column (available on a
93      * per-session basis from the global variable
94      * <code>@@identity</code>).
95      *
96      * @see org.apache.torque.adapter.DB#getIDMethodSQL(Object obj)
97      */
98     public String JavaDoc getIDMethodSQL(Object JavaDoc unused)
99     {
100         return "select @@identity";
101     }
102
103     /**
104      * Locks the specified table.
105      *
106      * @param con The JDBC connection to use.
107      * @param table The name of the table to lock.
108      * @throws SQLException No Statement could be created or executed.
109      */
110     public void lockTable(Connection JavaDoc con, String JavaDoc table) throws SQLException JavaDoc
111     {
112         Statement JavaDoc statement = con.createStatement();
113
114         StringBuffer JavaDoc stmt = new StringBuffer JavaDoc();
115         stmt.append("SELECT next_id FROM ")
116         .append(table)
117         .append(" FOR UPDATE");
118
119         statement.executeQuery(stmt.toString());
120     }
121
122     /**
123      * Unlocks the specified table.
124      *
125      * @param con The JDBC connection to use.
126      * @param table The name of the table to unlock.
127      * @throws SQLException No Statement could be created or executed.
128      */
129     public void unlockTable(Connection JavaDoc con, String JavaDoc table) throws SQLException JavaDoc
130     {
131         // Tables in Sybase are unlocked when a commit is issued. The
132 // user may have issued a commit but do it here to be sure.
133 con.commit();
134     }
135
136     /**
137      * This method is used to chek whether the database supports
138      * limiting the size of the resultset.
139      *
140      * @return LIMIT_STYLE_SYBASE.
141      * @deprecated This should not be exposed to the outside
142      */
143     public int getLimitStyle()
144     {
145         return DB.LIMIT_STYLE_SYBASE;
146     }
147
148     /**
149      * Return true for Sybase
150      * @see org.apache.torque.adapter.AbstractDBAdapter#supportsNativeLimit()
151      */
152     public boolean supportsNativeLimit()
153     {
154         return true;
155     }
156
157     /**
158      * Modify a query to add limit and offset values for Sybase.
159      *
160      * @param query The query to modify
161      * @param offset the offset Value
162      * @param limit the limit Value
163      *
164      * @throws TorqueException if any error occurs when building the query
165      */
166     public void generateLimits(Query query, int offset, int limit)
167         throws TorqueException
168     {
169         if (limit + offset > 0)
170         {
171             query.setRowcount(String.valueOf(limit + offset));
172         }
173         else if (limit + offset == 0)
174         {
175             // This is necessary to create the empty result set that Torque expects
176 query.getWhereClause().add(SqlExpression.build("1", new Integer JavaDoc(0), Criteria.EQUAL));
177         }
178     }
179
180     /**
181      * This method overrides the JDBC escapes used to format dates
182      * using a <code>DateFormat</code>. As of version 11, the Sybase
183      * JDBC driver does not implement JDBC 3.0 escapes.
184      *
185      * @param date the date to format
186      * @return The properly formatted date String.
187      */
188     public String JavaDoc getDateString(Date JavaDoc date)
189     {
190         char delim = getStringDelimiter();
191         return (delim + new SimpleDateFormat JavaDoc(DATE_FORMAT).format(date) + delim);
192     }
193
194     /**
195      * Determines whether backslashes (\) should be escaped in explicit SQL
196      * strings. If true is returned, a BACKSLASH will be changed to "\\".
197      * If false is returned, a BACKSLASH will be left as "\".
198      *
199      * Sybase (and MSSQL) doesn't define a default escape character,
200      * so false is returned.
201      *
202      * @return false
203      * @see org.apache.torque.adapter.DB#escapeText()
204      */
205     public boolean escapeText()
206     {
207         return false;
208     }
209
210     /**
211      * Whether an escape clause in like should be used.
212      * Example : select * from AUTHOR where AUTHOR.NAME like '\_%' ESCAPE '\';
213      *
214      * Sybase needs this, so this implementation always returns
215      * <code>true</code>.
216      *
217      * @return whether the escape clause should be appended or not.
218      */
219     public boolean useEscapeClauseForLike()
220     {
221         return true;
222     }
223 }
224
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