dbal.php

这些都是我以前学习是用到的源码

<?php
/** 
*
* @package dbal
* @version $Id: dbal.php,v 1.48 2006/11/25 20:00:56 naderman Exp $
* @copyright (c) 2005 phpBB Group 
* @license http://opensource.org/licenses/gpl-license.php GNU Public License 
*
*/

/**
* Database Abstraction Layer
* @package dbal
*/
class dbal
{
	var $db_connect_id;
	var $query_result;
	var $return_on_error = false;
	var $transaction = false;
	var $sql_time = 0;
	var $num_queries = array();
	var $open_queries = array();

	var $curtime = 0;
	var $query_hold = '';
	var $html_hold = '';
	var $sql_report = '';
	
	var $persistency = false;
	var $user = '';
	var $server = '';
	var $dbname = '';

	// Set to true if error triggered
	var $sql_error_triggered = false;

	// Holding the last sql query on sql error
	var $sql_error_sql = '';

	/**
	* Current sql layer
	*/
	var $sql_layer = '';

	/**
	* Constructor
	*/
	function dbal()
	{
		$this->num_queries = array(
			'cached'		=> 0,
			'normal'		=> 0,
			'total'			=> 0,
		);

		// Fill default sql layer based on the class being called.
		// This can be changed by the specified layer itself later if needed.
		$this->sql_layer = substr(get_class($this), 5);
	}

	/**
	* return on error or display error message
	*/
	function sql_return_on_error($fail = false)
	{
		$this->sql_error_triggered = false;
		$this->sql_error_sql = '';

		$this->return_on_error = $fail;
	}

	/**
	* Return number of sql queries and cached sql queries used
	*/
	function sql_num_queries($cached = false)
	{
		return ($cached) ? $this->num_queries['cached'] : $this->num_queries['normal'];
	}

	/**
	* Add to query count
	*/
	function sql_add_num_queries($cached = false)
	{
		$this->num_queries['cached'] += ($cached) ? 1 : 0;
		$this->num_queries['normal'] += ($cached) ? 0 : 1;
		$this->num_queries['total'] += 1;
	}

	/**
	* DBAL garbage collection, close sql connection
	*/
	function sql_close()
	{
		if (!$this->db_connect_id)
		{
			return false;
		}

		if ($this->transaction)
		{
			$this->sql_transaction('commit');
		}

		if (sizeof($this->open_queries))
		{
			foreach ($this->open_queries as $i_query_id => $query_id)
			{
				$this->sql_freeresult($query_id);
			}
		}
		
		return $this->_sql_close();
	}

	/**
	* Fetch all rows
	*/
	function sql_fetchrowset($query_id = false)
	{
		if ($query_id === false)
		{
			$query_id = $this->query_result;
		}

		if ($query_id !== false)
		{
			$result = array();
			while ($row = $this->sql_fetchrow($query_id))
			{
				$result[] = $row;
			}

			return $result;
		}
		
		return false;
	}

	/**
	* Fetch field
	* if rownum is false, the current row is used, else it is pointing to the row (zero-based)
	*/
	function sql_fetchfield($field, $rownum = false, $query_id = false)
	{
		global $cache;

		if ($query_id === false)
		{
			$query_id = $this->query_result;
		}

		if ($query_id !== false)
		{
			if ($rownum !== false)
			{
				$this->sql_rowseek($rownum, $query_id);
			}

			if (!is_object($query_id) && isset($cache->sql_rowset[$query_id]))
			{
				return $cache->sql_fetchfield($query_id, $field);
			}

			$row = $this->sql_fetchrow($query_id);
			return (isset($row[$field])) ? $row[$field] : false;
		}

		return false;
	}

	/**
	* SQL Transaction
	* @access private
	*/
	function sql_transaction($status = 'begin')
	{
		switch ($status)
		{
			case 'begin':
				// Commit previously opened transaction before opening another transaction
				if ($this->transaction)
				{
					$this->_sql_transaction('commit');
				}

				$result = $this->_sql_transaction('begin');
				$this->transaction = true;
			break;

			case 'commit':
				$result = $this->_sql_transaction('commit');
				$this->transaction = false;

				if (!$result)
				{
					$this->_sql_transaction('rollback');
				}
			break;

			case 'rollback':
				$result = $this->_sql_transaction('rollback');
				$this->transaction = false;
			break;

			default:
				$result = $this->_sql_transaction($status);
			break;
		}

		return $result;
	}

	/**
	* Build sql statement from array for insert/update/select statements
	*
	* Idea for this from Ikonboard
	* Possible query values: INSERT, INSERT_SELECT, MULTI_INSERT, UPDATE, SELECT
	*
	*/
	function sql_build_array($query, $assoc_ary = false)
	{
		if (!is_array($assoc_ary))
		{
			return false;
		}

		$fields = $values = array();

		if ($query == 'INSERT' || $query == 'INSERT_SELECT')
		{
			foreach ($assoc_ary as $key => $var)
			{
				$fields[] = $key;

				if (is_array($var) && is_string($var[0]))
				{
					// This is used for INSERT_SELECT(s)
					$values[] = $var[0];
				}
				else
				{
					$values[] = $this->_sql_validate_value($var);
				}
			}

			$query = ($query == 'INSERT') ? ' (' . implode(', ', $fields) . ') VALUES (' . implode(', ', $values) . ')' : ' (' . implode(', ', $fields) . ') SELECT ' . implode(', ', $values) . ' ';
		}
		else if ($query == 'MULTI_INSERT')
		{
			$ary = array();
			foreach ($assoc_ary as $id => $sql_ary)
			{
				// If by accident the sql array is only one-dimensional we build a normal insert statement
				if (!is_array($sql_ary))
				{
					return $this->sql_build_array('INSERT', $assoc_ary);
				}

				$values = array();
				foreach ($sql_ary as $key => $var)
				{
					$values[] = $this->_sql_validate_value($var);
				}
				$ary[] = '(' . implode(', ', $values) . ')';
			}

			$query = ' (' . implode(', ', array_keys($assoc_ary[0])) . ') VALUES ' . implode(', ', $ary);
		}
		else if ($query == 'UPDATE' || $query == 'SELECT')
		{
			$values = array();
			foreach ($assoc_ary as $key => $var)
			{
				$values[] = "$key = " . $this->_sql_validate_value($var);
			}
			$query = implode(($query == 'UPDATE') ? ', ' : ' AND ', $values);
		}

		return $query;
	}

	/**
	* Build IN, NOT IN, = and <> sql comparison string.
	* @access public
	*/
	function sql_in_set($field, $array, $negate = false)
	{
		if (!sizeof($array))
		{
			// Not optimal, but at least the backtrace should help in identifying where the problem lies.
			$this->sql_error('No values specified for SQL IN comparison');
		}

		if (!is_array($array))
		{
			$array = array($array);
		}

		if (sizeof($array) == 1)
		{
			@reset($array);
			$var = current($array);

			return $field . ($negate ? ' <> ' : ' = ') . $this->_sql_validate_value($var);
		}
		else
		{
			return $field . ($negate ? ' NOT IN ' : ' IN ') . '(' . implode(', ', array_map(array($this, '_sql_validate_value'), $array)) . ')';
		}
	}

	/**
	* Run more than one insert statement.
	*
	* @param string $table table name to run the statements on
	* @param array &$sql_ary multi-dimensional array holding the statement data.
	*
	* @return bool false if no statements were executed.
	* @access public
	*/
	function sql_multi_insert($table, &$sql_ary)
	{
		if (!sizeof($sql_ary))
		{
			return false;
		}

		switch ($this->sql_layer)
		{
			case 'mysql':
			case 'mysql4':
			case 'mysqli':
				$this->sql_query('INSERT INTO ' . $table . ' ' . $this->sql_build_array('MULTI_INSERT', $sql_ary));
			break;

			default:
				foreach ($sql_ary as $ary)
				{
					if (!is_array($ary))
					{
						return false;
					}

					$this->sql_query('INSERT INTO ' . $table . ' ' . $this->sql_build_array('INSERT', $ary));
				}
			break;
		}