一个php数据库操作类
<?PHP
class Database
{
// Singleton object. Leave $me alone.
private static $me;
public $readDB;
public $writeDB;
public $readHost;
public $writeHost;
public $name;
public $readUsername;
public $writeUsername;
public $readPassword;
public $writePassword;
public $onError; // Can be '', 'die', or 'redirect'
public $emailOnError;
public $queries;
public $result;
public $emailTo; // Where to send an error report
public $emailSubject;
public $errorUrl; // Where to redirect the user on error
// Singleton constructor
private function __construct()
{
$this->readHost = Config::get('dbReadHost');
$this->writeHost = Config::get('dbWriteHost');
$this->name = Config::get('dbName');
$this->readUsername = Config::get('dbReadUsername');
$this->writeUsername = Config::get('dbWriteUsername');
$this->readPassword = Config::get('dbReadPassword');
$this->writePassword = Config::get('dbWritePassword');
$this->onError = Config::get('dbOnError');
$this->emailOnError = Config::get('dbEmailOnError');
$this->readDB = false;
$this->writeDB = false;
$this->queries = array();
}
// Get Singleton object
public static function getDatabase()
{
if(is_null(self::$me))
self::$me = new Database();
return self::$me;
}
// Do we have a valid read-only database connection?
public function isReadConnected()
{
return is_resource($this->readDB) && get_resource_type($this->readDB) == 'mysql link';
}
// Do we have a valid read/write database connection?
public function isWriteConnected()
{
return is_resource($this->writeDB) && get_resource_type($this->writeDB) == 'mysql link';
}
// Do we have a valid database connection and have we selected a database?
public function databaseSelected()
{
if(!$this->isReadConnected()) return false;
$result = mysql_list_tables($this->name, $this->readDB);
return is_resource($result);
}
public function readConnect()
{
$this->readDB = mysql_connect($this->readHost, $this->readUsername, $this->readPassword) or $this->notify();
if($this->readDB === false) return false;
if(!empty($this->name))
mysql_select_db($this->name, $this->readDB) or $this->notify();
return $this->isReadConnected();
}
public function writeConnect()
{
$this->writeDB = mysql_connect($this->writeHost, $this->writeUsername, $this->writePassword) or $this->notify();
if($this->writeDB === false) return false;
if(!empty($this->name))
mysql_select_db($this->name, $this->writeDB) or $this->notify();
return $this->isWriteConnected();
}
public function query($sql, $args_to_prepare = null, $exception_on_missing_args = true)
{
// Read or Write connection?
$sql = trim($sql);
if(preg_match('/^(INSERT|UPDATE|REPLACE|DELETE)/i', $sql) == 0)
{
if(!$this->isReadConnected())
$this->readConnect();
$the_db = $this->readDB;
}
else
{
if(!$this->isWriteConnected())
$this->writeConnect();
$the_db = $this->writeDB;
}
// Allow for prepared arguments. Example:
// query("SELECT * FROM table WHERE id = :id:", array('id' => $some_val));
if(is_array($args_to_prepare))
{
foreach($args_to_prepare as $name => $val)
{
if(!is_int($val)) $val = $this->quote($val);
$sql = str_replace(":$name:", $val, $sql, $count);
if($exception_on_missing_args && (0 == $count))
throw new Exception(":$name: was not found in prepared SQL query.");
}
}
$this->queries[] = $sql;
$this->result = mysql_query($sql, $the_db) or $this->notify();
return $this->result;
}
// Returns the number of rows.
// You can pass in nothing, a string, or a db result
public function numRows($arg = null)
{
$result = $this->resulter($arg);
return ($result !== false) ? mysql_num_rows($result) : false;
}
// Returns true / false if the result has one or more rows
public function hasRows($arg = null)
{
$result = $this->resulter($arg);
return is_resource($result) && (mysql_num_rows($result) > 0);
}
// Returns the number of rows affected by the previous WRITE operation
public function affectedRows()
{
if(!$this->isWriteConnected()) return false;
return mysql_affected_rows($this->writeDB);
}
// Returns the auto increment ID generated by the previous insert statement
public function insertId()
{
if(!$this->isWriteConnected()) return false;
return mysql_insert_id($this->writeDB);
}
// Returns a single value.
// You can pass in nothing, a string, or a db result
public function getValue($arg = null)
{
$result = $this->resulter($arg);
return $this->hasRows($result) ? mysql_result($result, 0, 0) : false;
}
// Returns an array of the first value in each row.
// You can pass in nothing, a string, or a db result
public function getValues($arg = null)
{
$result = $this->resulter($arg);
if(!$this->hasRows($result)) return array();
$values = array();
mysql_data_seek($result, 0);
while($row = mysql_fetch_array($result, MYSQL_ASSOC))
$values[] = array_pop($row);
return $values;
}
// Returns the first row.
// You can pass in nothing, a string, or a db result
public function getRow($arg = null)
{
$result = $this->resulter($arg);
return $this->hasRows($result) ? mysql_fetch_array($result, MYSQL_ASSOC) : false;
}
// Returns an array of all the rows.
// You can pass in nothing, a string, or a db result
public function getRows($arg = null)
{
$result = $this->resulter($arg);
if(!$this->hasRows($result)) return array();
$rows = array();
mysql_data_seek($result, 0);
while($row = mysql_fetch_array($result, MYSQL_ASSOC))
$rows[] = $row;
return $rows;
}
// Escapes a value and wraps it in single quotes.
public function quote($var)
{
return "'" . $this->escape($var) . "'";
}
// Escapes a value.
public function escape($var)
{
if(!$this->isReadConnected()) $this->readConnect();
return mysql_real_escape_string($var, $this->readDB);
}
public function numQueries()
{
return count($this->queries);
}
public function lastQuery()
{
if($this->numQueries() > 0)
return $this->queries[$this->numQueries() - 1];
else
return false;
}
private function notify()
{
if($this->emailOnError === true)
{
$globals = print_r($GLOBALS, true);
$msg = '';
$msg .= "Url: " . full_url() . "n";
$msg .= "Date: " . dater() . "n";
$msg .= "Server: " . $_SERVER['SERVER_NAME'] . "n";
$msg .= "ReadDB Error:n" . mysql_error($this->readDB) . "nn";
$msg .= "WriteDB Error:n" . mysql_error($this->writeDB) . "nn";
ob_start();
debug_print_backtrace();
$trace = ob_get_contents();
ob_end_clean();
$msg .= $trace . "nn";
$msg .= $globals;
mail($this->emailTo, $this->emailSubject, $msg);
}
if($this->onError == 'die')
{
echo "<p style='border:5px solid red;background-color:#fff;padding:5px;'><strong>Read Database Error:</strong><br/>" . mysql_error($this->readDB) . "</p>";
echo "<p style='border:5px solid red;background-color:#fff;padding:5px;'><strong>Write Database Error:</strong><br/>" . mysql_error($this->writeDB) . "</p>";
echo "<p style='border:5px solid red;background-color:#fff;padding:5px;'><strong>Last Query:</strong><br/>" . $this->lastQuery() . "</p>";
echo "<pre>";
debug_print_backtrace();
echo "</pre>";
exit;
}
if($this->onError == 'redirect')
{
redirect($this->errorUrl);
}
}
// Takes nothing, a MySQL result, or a query string and returns
// the correspsonding MySQL result resource or false if none available.
private function resulter($arg = null)
{
if(is_null($arg) && is_resource($this->result))
return $this->result;
elseif(is_resource($arg))
return $arg;
elseif(is_string($arg))
{
$this->query($arg);
if(is_resource($this->result))
return $this->result;
else
return false;
}
else
return false;
}
}
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