1 | <?php |
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2 | |
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3 | /** |
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4 | * Return data from the persistent cache. Data may be stored as either plain text or as serialized data. |
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5 | * cache_get will automatically return unserialized objects and arrays. |
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6 | * |
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7 | * @param $cid |
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8 | * The cache ID of the data to retrieve. |
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9 | * @param $table |
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10 | * The table $table to store the data in. Valid core values are 'cache_filter', |
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11 | * 'cache_menu', 'cache_page', or 'cache' for the default cache. |
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12 | * |
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13 | * @see cache_set() |
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14 | */ |
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15 | function cache_get($cid, $table = 'cache') { |
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16 | global $user; |
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17 | |
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18 | // Garbage collection necessary when enforcing a minimum cache lifetime |
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19 | $cache_flush = variable_get('cache_flush_'. $table, 0); |
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20 | if ($cache_flush && ($cache_flush + variable_get('cache_lifetime', 0) <= time())) { |
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21 | // Reset the variable immediately to prevent a meltdown in heavy load situations. |
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22 | variable_set('cache_flush_'. $table, 0); |
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23 | // Time to flush old cache data |
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24 | db_query("DELETE FROM {". $table ."} WHERE expire != %d AND expire <= %d", CACHE_PERMANENT, $cache_flush); |
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25 | } |
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26 | |
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27 | $cache = db_fetch_object(db_query("SELECT data, created, headers, expire, serialized FROM {". $table ."} WHERE cid = '%s'", $cid)); |
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28 | if (isset($cache->data)) { |
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29 | // If the data is permanent or we're not enforcing a minimum cache lifetime |
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30 | // always return the cached data. |
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31 | if ($cache->expire == CACHE_PERMANENT || !variable_get('cache_lifetime', 0)) { |
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32 | $cache->data = db_decode_blob($cache->data); |
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33 | if ($cache->serialized) { |
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34 | $cache->data = unserialize($cache->data); |
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35 | } |
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36 | } |
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37 | // If enforcing a minimum cache lifetime, validate that the data is |
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38 | // currently valid for this user before we return it by making sure the |
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39 | // cache entry was created before the timestamp in the current session's |
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40 | // cache timer. The cache variable is loaded into the $user object by |
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41 | // sess_read() in session.inc. |
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42 | else { |
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43 | if (isset($user->cache) && $user->cache > $cache->created) { |
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44 | // This cache data is too old and thus not valid for us, ignore it. |
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45 | return 0; |
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46 | } |
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47 | else { |
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48 | $cache->data = db_decode_blob($cache->data); |
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49 | if ($cache->serialized) { |
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50 | $cache->data = unserialize($cache->data); |
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51 | } |
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52 | } |
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53 | } |
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54 | return $cache; |
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55 | } |
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56 | return 0; |
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57 | } |
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58 | |
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59 | /** |
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60 | * Store data in the persistent cache. |
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61 | * |
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62 | * The persistent cache is split up into four database |
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63 | * tables. Contributed modules can add additional tables. |
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64 | * |
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65 | * 'cache_page': This table stores generated pages for anonymous |
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66 | * users. This is the only table affected by the page cache setting on |
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67 | * the administrator panel. |
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68 | * |
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69 | * 'cache_menu': Stores the cachable part of the users' menus. |
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70 | * |
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71 | * 'cache_filter': Stores filtered pieces of content. This table is |
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72 | * periodically cleared of stale entries by cron. |
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73 | * |
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74 | * 'cache': Generic cache storage table. |
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75 | * |
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76 | * The reasons for having several tables are as follows: |
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77 | * |
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78 | * - smaller tables allow for faster selects and inserts |
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79 | * - we try to put fast changing cache items and rather static |
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80 | * ones into different tables. The effect is that only the fast |
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81 | * changing tables will need a lot of writes to disk. The more |
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82 | * static tables will also be better cachable with MySQL's query cache |
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83 | * |
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84 | * @param $cid |
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85 | * The cache ID of the data to store. |
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86 | * @param $data |
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87 | * The data to store in the cache. Complex data types will be automatically serialized before insertion. |
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88 | * Strings will be stored as plain text and not serialized. |
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89 | * @param $table |
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90 | * The table $table to store the data in. Valid core values are 'cache_filter', |
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91 | * 'cache_menu', 'cache_page', or 'cache'. |
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92 | * @param $expire |
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93 | * One of the following values: |
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94 | * - CACHE_PERMANENT: Indicates that the item should never be removed unless |
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95 | * explicitly told to using cache_clear_all() with a cache ID. |
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96 | * - CACHE_TEMPORARY: Indicates that the item should be removed at the next |
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97 | * general cache wipe. |
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98 | * - A Unix timestamp: Indicates that the item should be kept at least until |
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99 | * the given time, after which it behaves like CACHE_TEMPORARY. |
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100 | * @param $headers |
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101 | * A string containing HTTP header information for cached pages. |
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102 | * |
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103 | * @see cache_get() |
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104 | */ |
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105 | function cache_set($cid, $data, $table = 'cache', $expire = CACHE_PERMANENT, $headers = NULL) { |
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106 | $serialized = 0; |
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107 | if (is_object($data) || is_array($data)) { |
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108 | $data = serialize($data); |
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109 | $serialized = 1; |
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110 | } |
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111 | $created = time(); |
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112 | db_query("UPDATE {". $table ."} SET data = %b, created = %d, expire = %d, headers = '%s', serialized = %d WHERE cid = '%s'", $data, $created, $expire, $headers, $serialized, $cid); |
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113 | if (!db_affected_rows()) { |
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114 | @db_query("INSERT INTO {". $table ."} (cid, data, created, expire, headers, serialized) VALUES ('%s', %b, %d, %d, '%s', %d)", $cid, $data, $created, $expire, $headers, $serialized); |
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115 | } |
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116 | } |
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117 | |
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118 | /** |
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119 | * |
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120 | * Expire data from the cache. If called without arguments, expirable |
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121 | * entries will be cleared from the cache_page and cache_block tables. |
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122 | * |
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123 | * @param $cid |
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124 | * If set, the cache ID to delete. Otherwise, all cache entries that can |
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125 | * expire are deleted. |
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126 | * |
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127 | * @param $table |
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128 | * If set, the table $table to delete from. Mandatory |
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129 | * argument if $cid is set. |
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130 | * |
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131 | * @param $wildcard |
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132 | * If $wildcard is TRUE, cache IDs starting with $cid are deleted in |
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133 | * addition to the exact cache ID specified by $cid. If $wildcard is |
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134 | * TRUE and $cid is '*' then the entire table $table is emptied. |
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135 | */ |
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136 | function cache_clear_all($cid = NULL, $table = NULL, $wildcard = FALSE) { |
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137 | global $user; |
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138 | |
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139 | if (!isset($cid) && !isset($table)) { |
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140 | // Clear the block cache first, so stale data will |
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141 | // not end up in the page cache. |
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142 | cache_clear_all(NULL, 'cache_block'); |
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143 | cache_clear_all(NULL, 'cache_page'); |
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144 | return; |
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145 | } |
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146 | |
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147 | if (empty($cid)) { |
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148 | if (variable_get('cache_lifetime', 0)) { |
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149 | // We store the time in the current user's $user->cache variable which |
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150 | // will be saved into the sessions table by sess_write(). We then |
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151 | // simulate that the cache was flushed for this user by not returning |
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152 | // cached data that was cached before the timestamp. |
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153 | $user->cache = time(); |
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154 | |
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155 | $cache_flush = variable_get('cache_flush_'. $table, 0); |
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156 | if ($cache_flush == 0) { |
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157 | // This is the first request to clear the cache, start a timer. |
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158 | variable_set('cache_flush_'. $table, time()); |
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159 | } |
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160 | else if (time() > ($cache_flush + variable_get('cache_lifetime', 0))) { |
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161 | // Clear the cache for everyone, cache_lifetime seconds have |
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162 | // passed since the first request to clear the cache. |
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163 | db_query("DELETE FROM {". $table ."} WHERE expire != %d AND expire < %d", CACHE_PERMANENT, time()); |
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164 | variable_set('cache_flush_'. $table, 0); |
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165 | } |
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166 | } |
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167 | else { |
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168 | // No minimum cache lifetime, flush all temporary cache entries now. |
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169 | db_query("DELETE FROM {". $table ."} WHERE expire != %d AND expire < %d", CACHE_PERMANENT, time()); |
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170 | } |
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171 | } |
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172 | else { |
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173 | if ($wildcard) { |
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174 | if ($cid == '*') { |
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175 | db_query("TRUNCATE TABLE {". $table ."}"); |
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176 | } |
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177 | else { |
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178 | db_query("DELETE FROM {". $table ."} WHERE cid LIKE '%s%%'", $cid); |
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179 | } |
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180 | } |
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181 | else { |
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182 | db_query("DELETE FROM {". $table ."} WHERE cid = '%s'", $cid); |
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183 | } |
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184 | } |
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185 | } |
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186 | |
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