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org.apache.torque.adapter.AbstractDBAdapter |
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1 | package org.apache.torque.adapter; |
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2 | ||
3 | /* |
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4 | * Licensed to the Apache Software Foundation (ASF) under one |
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5 | * or more contributor license agreements. See the NOTICE file |
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6 | * distributed with this work for additional information |
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7 | * regarding copyright ownership. The ASF licenses this file |
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8 | * to you under the Apache License, Version 2.0 (the |
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9 | * "License"); you may not use this file except in compliance |
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10 | * with the License. You may obtain a copy of the License at |
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11 | * |
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12 | * http://www.apache.org/licenses/LICENSE-2.0 |
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13 | * |
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14 | * Unless required by applicable law or agreed to in writing, |
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15 | * software distributed under the License is distributed on an |
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16 | * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
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17 | * KIND, either express or implied. See the License for the |
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18 | * specific language governing permissions and limitations |
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19 | * under the License. |
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20 | */ |
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21 | ||
22 | import java.sql.Connection; |
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23 | import java.sql.SQLException; |
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24 | import java.sql.Timestamp; |
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25 | import java.util.Date; |
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26 | ||
27 | import org.apache.torque.TorqueException; |
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28 | import org.apache.torque.util.Query; |
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29 | ||
30 | /** |
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31 | * This class is the abstract base for any database adapter |
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32 | * Support for new databases is added by subclassing this |
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33 | * class and implementing its abstract methods, and by |
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34 | * registering the new database adapter and its corresponding |
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35 | * JDBC driver in the service configuration file. |
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36 | * |
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37 | * <p>The Torque database adapters exist to present a uniform |
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38 | * interface to database access across all available databases. Once |
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39 | * the necessary adapters have been written and configured, |
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40 | * transparent swapping of databases is theoretically supported with |
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41 | * <i>zero code changes</i> and minimal configuration file |
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42 | * modifications. |
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43 | * |
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44 | * <p>Torque uses the driver class name to find the right adapter. |
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45 | * A JDBC driver corresponding to your adapter must be added to the properties |
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46 | * file, using the fully-qualified class name of the driver. If no driver is |
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47 | * specified for your database, <code>driver.default</code> is used. |
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48 | * |
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49 | * <pre> |
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50 | * #### MySQL MM Driver |
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51 | * database.default.driver=org.gjt.mm.mysql.Driver |
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52 | * database.default.url=jdbc:mysql://localhost/DATABASENAME |
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53 | * </pre> |
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54 | * |
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55 | * @author <a href="mailto:jon@latchkey.com">Jon S. Stevens</a> |
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56 | * @author <a href="mailto:bmclaugh@algx.net">Brett McLaughlin</a> |
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57 | * @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a> |
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58 | * @author <a href="mailto:vido@ldh.org">Augustin Vidovic</a> |
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59 | * @version $Id: DB.java 393063 2006-04-10 20:59:16Z tfischer $ |
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60 | */ |
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61 | public abstract class AbstractDBAdapter implements DB |
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62 | { |
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63 | /** |
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64 | * Empty constructor. |
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65 | */ |
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66 | protected AbstractDBAdapter() |
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67 | 90 | { |
68 | 90 | } |
69 | ||
70 | /** |
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71 | * This method is used to ignore case. |
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72 | * |
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73 | * @param in The string to transform to upper case. |
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74 | * @return The upper case string. |
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75 | */ |
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76 | public abstract String toUpperCase(String in); |
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77 | ||
78 | /** |
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79 | * Returns the character used to indicate the beginning and end of |
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80 | * a piece of text used in a SQL statement (generally a single |
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81 | * quote). |
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82 | * |
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83 | * @return The text delimeter. |
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84 | */ |
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85 | public char getStringDelimiter() |
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86 | { |
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87 | 24 | return '\''; |
88 | } |
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89 | ||
90 | /** |
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91 | * Returns the constant from the {@link |
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92 | * org.apache.torque.adapter.IDMethod} interface denoting which |
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93 | * type of primary key generation method this type of RDBMS uses. |
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94 | * |
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95 | * @return IDMethod constant |
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96 | */ |
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97 | public abstract String getIDMethodType(); |
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98 | ||
99 | /** |
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100 | * Returns SQL used to get the most recently inserted primary key. |
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101 | * Databases which have no support for this return |
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102 | * <code>null</code>. |
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103 | * |
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104 | * @param obj Information used for key generation. |
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105 | * @return The most recently inserted database key. |
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106 | */ |
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107 | public abstract String getIDMethodSQL(Object obj); |
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108 | ||
109 | /** |
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110 | * Locks the specified table. |
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111 | * |
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112 | * @param con The JDBC connection to use. |
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113 | * @param table The name of the table to lock. |
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114 | * @throws SQLException No Statement could be created or executed. |
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115 | */ |
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116 | public abstract void lockTable(Connection con, String table) |
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117 | throws SQLException; |
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118 | ||
119 | /** |
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120 | * Unlocks the specified table. |
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121 | * |
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122 | * @param con The JDBC connection to use. |
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123 | * @param table The name of the table to unlock. |
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124 | * @throws SQLException No Statement could be created or executed. |
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125 | */ |
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126 | public abstract void unlockTable(Connection con, String table) |
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127 | throws SQLException; |
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128 | ||
129 | /** |
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130 | * This method is used to ignore case. |
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131 | * |
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132 | * @param in The string whose case to ignore. |
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133 | * @return The string in a case that can be ignored. |
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134 | */ |
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135 | public abstract String ignoreCase(String in); |
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136 | ||
137 | /** |
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138 | * This method is used to ignore case in an ORDER BY clause. |
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139 | * Usually it is the same as ignoreCase, but some databases |
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140 | * (Interbase for example) does not use the same SQL in ORDER BY |
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141 | * and other clauses. |
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142 | * |
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143 | * @param in The string whose case to ignore. |
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144 | * @return The string in a case that can be ignored. |
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145 | */ |
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146 | public String ignoreCaseInOrderBy(String in) |
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147 | { |
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148 | 12 | return ignoreCase(in); |
149 | } |
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150 | ||
151 | /** |
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152 | * This method is used to check whether the database natively |
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153 | * supports limiting the size of the resultset. |
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154 | * |
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155 | * @return True if the database natively supports limiting the |
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156 | * size of the resultset. |
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157 | */ |
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158 | public boolean supportsNativeLimit() |
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159 | { |
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160 | 0 | return false; |
161 | } |
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162 | ||
163 | /** |
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164 | * This method is used to check whether the database natively |
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165 | * supports returning results starting at an offset position other |
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166 | * than 0. |
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167 | * |
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168 | * @return True if the database natively supports returning |
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169 | * results starting at an offset position other than 0. |
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170 | */ |
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171 | public boolean supportsNativeOffset() |
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172 | { |
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173 | 0 | return false; |
174 | } |
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175 | ||
176 | /** |
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177 | * This method is used to generate the database specific query |
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178 | * extension to limit the number of record returned. |
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179 | * |
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180 | * @param query The query to modify |
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181 | * @param offset the offset Value |
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182 | * @param limit the limit Value |
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183 | * |
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184 | * @throws TorqueException if any error occurs when building the query |
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185 | */ |
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186 | public void generateLimits(Query query, int offset, class="keyword">int limit) |
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187 | throws TorqueException |
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188 | { |
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189 | 0 | if (supportsNativeLimit()) |
190 | { |
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191 | 0 | query.setLimit(String.valueOf(limit)); |
192 | } |
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193 | 0 | } |
194 | ||
195 | /** |
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196 | * This method is for the SqlExpression.quoteAndEscape rules. The rule is, |
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197 | * any string in a SqlExpression with a BACKSLASH will either be changed to |
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198 | * "\\" or left as "\". SapDB does not need the escape character. |
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199 | * |
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200 | * @return true if the database needs to escape text in SqlExpressions. |
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201 | */ |
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202 | ||
203 | public boolean escapeText() |
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204 | { |
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205 | 60174 | return true; |
206 | } |
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207 | ||
208 | /** |
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209 | * This method is used to check whether the database supports |
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210 | * limiting the size of the resultset. |
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211 | * |
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212 | * @return The limit style for the database. |
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213 | * @deprecated This should not be exposed to the outside |
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214 | */ |
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215 | public int getLimitStyle() |
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216 | { |
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217 | 0 | return LIMIT_STYLE_NONE; |
218 | } |
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219 | ||
220 | /** |
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221 | * This method is used to format any date string. |
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222 | * Database can use different default date formats. |
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223 | * |
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224 | * @param date the Date to format |
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225 | * @return The proper date formatted String. |
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226 | */ |
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227 | public String getDateString(Date date) |
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228 | { |
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229 | 0 | Timestamp ts = null; |
230 | 0 | if (date instanceof Timestamp) |
231 | { |
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232 | 0 | ts = (Timestamp) date; |
233 | } |
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234 | else |
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235 | { |
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236 | 0 | ts = new Timestamp(date.getTime()); |
237 | } |
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238 | ||
239 | 0 | return ("{ts '" + ts + "'}"); |
240 | } |
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241 | ||
242 | /** |
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243 | * This method is used to format a boolean string. |
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244 | * |
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245 | * @param b the Boolean to format |
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246 | * @return The proper date formatted String. |
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247 | */ |
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248 | public String getBooleanString(Boolean b) |
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249 | { |
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250 | 6 | return (Boolean.TRUE.equals(b) ? "1" : "0"); |
251 | } |
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252 | ||
253 | /** |
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254 | * Whether ILIKE should be used for case insensitive like clauses. |
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255 | * |
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256 | * As most databases do not use ILIKE, this implementation returns false. |
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257 | * This behaviour may be overwritten in subclasses. |
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258 | * |
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259 | * @return true if ilike should be used for case insensitive likes, |
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260 | * false if ignoreCase should be applied to the compared strings. |
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261 | */ |
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262 | public boolean useIlike() |
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263 | { |
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264 | 24 | return false; |
265 | } |
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266 | ||
267 | /** |
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268 | * Whether an escape clause in like should be used. |
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269 | * Example : select * from AUTHOR where AUTHOR.NAME like '\_%' ESCAPE '\'; |
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270 | * |
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271 | * As most databases do not need the escape clause, this implementation |
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272 | * always returns <code>false</code>. This behaviour can be overwritten |
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273 | * in subclasses. |
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274 | * |
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275 | * @return whether the escape clause should be appended or not. |
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276 | */ |
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277 | public boolean useEscapeClauseForLike() |
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278 | { |
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279 | 6 | return false; |
280 | } |
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281 | } |
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