Added a default _update() method to CI_DB_active_record
diff --git a/system/database/DB_active_rec.php b/system/database/DB_active_rec.php
index 34a88ce..22b5708 100644
--- a/system/database/DB_active_rec.php
+++ b/system/database/DB_active_rec.php
@@ -1520,6 +1520,33 @@
 	// --------------------------------------------------------------------
 
 	/**
+	 * Update statement
+	 *
+	 * Generates a platform-specific update string from the supplied data
+	 *
+	 * @param	string	the table name
+	 * @param	array	the update data
+	 * @param	array	the where clause
+	 * @param	array	the orderby clause
+	 * @param	array	the limit clause
+	 * @return	string
+	 */
+	protected function _update($table, $values, $where, $orderby = array(), $limit = FALSE)
+	{
+		foreach ($values as $key => $val)
+		{
+			$valstr[] = $key.' = '.$val;
+		}
+
+		return 'UPDATE '.$table.' SET '.implode(', ', $valstr)
+			.(($where != '' && count($where) > 0) ? ' WHERE '.implode(' ', $where) : '')
+			.(count($orderby) > 0 ? ' ORDER BY '.implode(', ', $orderby) : '')
+			.($limit ? ' LIMIT '.$limit : '');
+	}
+
+	// --------------------------------------------------------------------
+
+	/**
 	 * Validate Update
 	 *
 	 * This method is used by both update() and get_compiled_update() to
diff --git a/system/database/drivers/cubrid/cubrid_driver.php b/system/database/drivers/cubrid/cubrid_driver.php
index d35808e..426797f 100644
--- a/system/database/drivers/cubrid/cubrid_driver.php
+++ b/system/database/drivers/cubrid/cubrid_driver.php
@@ -515,41 +515,6 @@
 	// --------------------------------------------------------------------
 
 	/**
-	 * Update statement
-	 *
-	 * Generates a platform-specific update string from the supplied data
-	 *
-	 * @param	string	the table name
-	 * @param	array	the update data
-	 * @param	array	the where clause
-	 * @param	array	the orderby clause
-	 * @param	array	the limit clause
-	 * @return	string
-	 */
-	protected function _update($table, $values, $where, $orderby = array(), $limit = FALSE)
-	{
-		foreach ($values as $key => $val)
-		{
-			$valstr[] = sprintf('"%s" = %s', $key, $val);
-		}
-
-		$limit = ( ! $limit) ? '' : ' LIMIT '.$limit;
-
-		$orderby = (count($orderby) >= 1)?' ORDER BY '.implode(", ", $orderby):'';
-
-		$sql = "UPDATE ".$table." SET ".implode(', ', $valstr);
-
-		$sql .= ($where != '' AND count($where) >=1) ? " WHERE ".implode(" ", $where) : '';
-
-		$sql .= $orderby.$limit;
-
-		return $sql;
-	}
-
-	// --------------------------------------------------------------------
-
-
-	/**
 	 * Update_Batch statement
 	 *
 	 * Generates a platform-specific batch update string from the supplied data
diff --git a/system/database/drivers/mssql/mssql_driver.php b/system/database/drivers/mssql/mssql_driver.php
index f46b954..3604e80 100644
--- a/system/database/drivers/mssql/mssql_driver.php
+++ b/system/database/drivers/mssql/mssql_driver.php
@@ -466,41 +466,6 @@
 	// --------------------------------------------------------------------
 
 	/**
-	 * Update statement
-	 *
-	 * Generates a platform-specific update string from the supplied data
-	 *
-	 * @param	string	the table name
-	 * @param	array	the update data
-	 * @param	array	the where clause
-	 * @param	array	the orderby clause
-	 * @param	array	the limit clause
-	 * @return	string
-	 */
-	protected function _update($table, $values, $where, $orderby = array(), $limit = FALSE)
-	{
-		foreach ($values as $key => $val)
-		{
-			$valstr[] = $key." = ".$val;
-		}
-
-		$limit = ( ! $limit) ? '' : ' LIMIT '.$limit;
-
-		$orderby = (count($orderby) >= 1)?' ORDER BY '.implode(", ", $orderby):'';
-
-		$sql = "UPDATE ".$table." SET ".implode(', ', $valstr);
-
-		$sql .= ($where != '' AND count($where) >=1) ? " WHERE ".implode(" ", $where) : '';
-
-		$sql .= $orderby.$limit;
-
-		return $sql;
-	}
-
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Truncate statement
 	 *
 	 * Generates a platform-specific truncate string from the supplied data
diff --git a/system/database/drivers/mysqli/mysqli_driver.php b/system/database/drivers/mysqli/mysqli_driver.php
index 3a835b4..565e3f4 100644
--- a/system/database/drivers/mysqli/mysqli_driver.php
+++ b/system/database/drivers/mysqli/mysqli_driver.php
@@ -514,33 +514,6 @@
 	// --------------------------------------------------------------------
 
 	/**
-	 * Update statement
-	 *
-	 * Generates a platform-specific update string from the supplied data
-	 *
-	 * @param	string	the table name
-	 * @param	array	the update data
-	 * @param	array	the where clause
-	 * @param	array	the orderby clause
-	 * @param	array	the limit clause
-	 * @return	string
-	 */
-	protected function _update($table, $values, $where, $orderby = array(), $limit = FALSE)
-	{
-		foreach ($values as $key => $val)
-		{
-			$valstr[] = $key.' = '.$val;
-		}
-
-		return 'UPDATE '.$table.' SET '.implode(', ', $valstr)
-			.(($where != '' && count($where) > 0) ? ' WHERE '.implode(' ', $where) : '')
-			.(count($orderby) > 0 ? ' ORDER BY '.implode(', ', $orderby) : '')
-			.( ! $limit ? '' : ' LIMIT '.$limit);
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Update_Batch statement
 	 *
 	 * Generates a platform-specific batch update string from the supplied data
diff --git a/system/database/drivers/oci8/oci8_driver.php b/system/database/drivers/oci8/oci8_driver.php
index c9f3e55..65ae1ea 100644
--- a/system/database/drivers/oci8/oci8_driver.php
+++ b/system/database/drivers/oci8/oci8_driver.php
@@ -645,33 +645,6 @@
 	// --------------------------------------------------------------------
 
 	/**
-	 * Update statement
-	 *
-	 * Generates a platform-specific update string from the supplied data
-	 *
-	 * @param	string	the table name
-	 * @param	array	the update data
-	 * @param	array	the where clause
-	 * @param	array	the orderby clause
-	 * @param	array	the limit clause
-	 * @return	string
-	 */
-	protected function _update($table, $values, $where, $orderby = array(), $limit = FALSE)
-	{
-		foreach ($values as $key => $val)
-		{
-			$valstr[] = $key.' = '.$val;
-		}
-
-		return 'UPDATE '.$table.' SET '.implode(', ', $valstr)
-			.(($where != '' && count($where) > 0) ? ' WHERE '.implode(' ', $where) : '')
-			.(count($orderby) > 0 ? ' ORDER BY '.implode(', ', $orderby) : '')
-			.( ! $limit ? '' : ' LIMIT '.$limit);
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Truncate statement
 	 *
 	 * Generates a platform-specific truncate string from the supplied data
diff --git a/system/database/drivers/odbc/odbc_driver.php b/system/database/drivers/odbc/odbc_driver.php
index 34f4106..bab8f58 100644
--- a/system/database/drivers/odbc/odbc_driver.php
+++ b/system/database/drivers/odbc/odbc_driver.php
@@ -405,41 +405,6 @@
 	// --------------------------------------------------------------------
 
 	/**
-	 * Update statement
-	 *
-	 * Generates a platform-specific update string from the supplied data
-	 *
-	 * @param	string	the table name
-	 * @param	array	the update data
-	 * @param	array	the where clause
-	 * @param	array	the orderby clause
-	 * @param	array	the limit clause
-	 * @return	string
-	 */
-	protected function _update($table, $values, $where, $orderby = array(), $limit = FALSE)
-	{
-		foreach ($values as $key => $val)
-		{
-			$valstr[] = $key." = ".$val;
-		}
-
-		$limit = ( ! $limit) ? '' : ' LIMIT '.$limit;
-
-		$orderby = (count($orderby) >= 1)?' ORDER BY '.implode(", ", $orderby):'';
-
-		$sql = "UPDATE ".$table." SET ".implode(', ', $valstr);
-
-		$sql .= ($where != '' AND count($where) >=1) ? " WHERE ".implode(" ", $where) : '';
-
-		$sql .= $orderby.$limit;
-
-		return $sql;
-	}
-
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Truncate statement
 	 *
 	 * Generates a platform-specific truncate string from the supplied data
diff --git a/system/database/drivers/pdo/pdo_driver.php b/system/database/drivers/pdo/pdo_driver.php
index 17c9f5e..9a08f9d 100644
--- a/system/database/drivers/pdo/pdo_driver.php
+++ b/system/database/drivers/pdo/pdo_driver.php
@@ -668,37 +668,6 @@
 	// --------------------------------------------------------------------
 
 	/**
-	 * Update statement
-	 *
-	 * Generates a platform-specific update string from the supplied data
-	 *
-	 * @param	string	the table name
-	 * @param	array	the update data
-	 * @param	array	the where clause
-	 * @param	array	the orderby clause
-	 * @param	array	the limit clause
-	 * @return	string
-	 */
-	protected function _update($table, $values, $where, $orderby = array(), $limit = FALSE)
-	{
-		foreach ($values as $key => $val)
-		{
-			$valstr[] = $key." = ".$val;
-		}
-
-		$limit   = ( ! $limit) ? '' : ' LIMIT '.$limit;
-		$orderby = (count($orderby) >= 1) ? ' ORDER BY '.implode(', ', $orderby) : '';
-
-		$sql  = 'UPDATE '.$this->_from_tables($table).' SET '.implode(', ', $valstr);
-		$sql .= ($where != '' && count($where) >= 1) ? ' WHERE '.implode(' ', $where) : '';
-		$sql .= $orderby.$limit;
-
-		return $sql;
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Update_Batch statement
 	 *
 	 * Generates a platform-specific batch update string from the supplied data
diff --git a/system/database/drivers/sqlite/sqlite_driver.php b/system/database/drivers/sqlite/sqlite_driver.php
index 5bfa42b..6274202 100644
--- a/system/database/drivers/sqlite/sqlite_driver.php
+++ b/system/database/drivers/sqlite/sqlite_driver.php
@@ -428,41 +428,6 @@
 	// --------------------------------------------------------------------
 
 	/**
-	 * Update statement
-	 *
-	 * Generates a platform-specific update string from the supplied data
-	 *
-	 * @param	string	the table name
-	 * @param	array	the update data
-	 * @param	array	the where clause
-	 * @param	array	the orderby clause
-	 * @param	array	the limit clause
-	 * @return	string
-	 */
-	protected function _update($table, $values, $where, $orderby = array(), $limit = FALSE)
-	{
-		foreach ($values as $key => $val)
-		{
-			$valstr[] = $key." = ".$val;
-		}
-
-		$limit = ( ! $limit) ? '' : ' LIMIT '.$limit;
-
-		$orderby = (count($orderby) >= 1)?' ORDER BY '.implode(", ", $orderby):'';
-
-		$sql = "UPDATE ".$table." SET ".implode(', ', $valstr);
-
-		$sql .= ($where != '' AND count($where) >=1) ? " WHERE ".implode(" ", $where) : '';
-
-		$sql .= $orderby.$limit;
-
-		return $sql;
-	}
-
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Truncate statement
 	 *
 	 * Generates a platform-specific truncate string from the supplied data
diff --git a/system/database/drivers/sqlite3/sqlite3_driver.php b/system/database/drivers/sqlite3/sqlite3_driver.php
index 269b461..7d6de80 100644
--- a/system/database/drivers/sqlite3/sqlite3_driver.php
+++ b/system/database/drivers/sqlite3/sqlite3_driver.php
@@ -399,33 +399,6 @@
 	// --------------------------------------------------------------------
 
 	/**
-	 * Update statement
-	 *
-	 * Generates a platform-specific update string from the supplied data
-	 *
-	 * @param	string	the table name
-	 * @param	array	the update data
-	 * @param	array	the where clause
-	 * @param	array	the orderby clause
-	 * @param	array	the limit clause
-	 * @return	string
-	 */
-	protected function _update($table, $values, $where, $orderby = array(), $limit = FALSE)
-	{
-		foreach ($values as $key => $val)
-		{
-			$valstr[] = $key.' = '.$val;
-		}
-
-		return 'UPDATE '.$table.' SET '.implode(', ', $valstr)
-			.(($where != '' && count($where) > 0) ? ' WHERE '.implode(' ', $where) : '')
-			.(count($orderby) > 0 ? ' ORDER BY '.implode(', ', $orderby) : '')
-			.( ! $limit ? '' : ' LIMIT '.$limit);
-	}
-
-	// --------------------------------------------------------------------
-
-	/**
 	 * Truncate statement
 	 *
 	 * Generates a platform-specific truncate string from the supplied data