php读取资料

程序员文章站 2022-05-12 19:24:15

...

php读取文件

1。php存文件的时候$testfilename2居然是非要单引号才行，要不然用双引号会报错，以后用变量的时候应该多用单引号

$testfilename2='D:\ProgramFiles2\AppServ\www\catch28\admin\testmethod6.html';//文件名,可以为.php或者.txt等文本文件

file_put_contents($testfilename,'');

2。mysql_free_result() 在update的操作的时候不需要调用：

mysql_free_result

(PHP 4, PHP 5)

mysql_free_result ― Free result memory

Description

bool mysql_free_result ( resource $result )

mysql_free_result() will free all memory associated with the result identifier result.

mysql_free_result() only needs to be called if you are concerned about how much memory is being used for queries that return large result sets. All associated result memory is automatically freed at the end of the script's execution.

Parameters

result

The result resource that is being evaluated. This result comes from a call to mysql_query().

Return Values

Returns TRUE on success or FALSE on failure.

If a non-resource is used for the result, an error of level E_WARNING will be emitted. It's worth noting that mysql_query() only returns a resource for SELECT, SHOW, EXPLAIN, and DESCRIBE queries.

Examples

Example #1 A mysql_free_result() example


$result?=?mysql_query("SELECT?id,email?FROM?people?WHERE?id?=?'42'");
if?(!$result)?{
????echo?'Could?not?run?query:?'?.?mysql_error();
????exit;
}
/*?Use?the?result,?assuming?we're?done?with?it?afterwards?*/
$row?=?mysql_fetch_assoc($result);

/*?Now?we?free?up?the?result?and?continue?on?with?our?script?*/
mysql_free_result($result);

echo?$row['id'];
echo?$row['email'];
?>

Notes

Note: For backward compatibility, the following deprecated alias may be used: mysql_freeresult()

First, what is mysql_free_result()? When you make mySQL database queries that return large sets of data, it can cause your server to bog down because those results are hogging up a lot of memory. On a high-traffic site, it can actually crash your server as more and more of those results build up. So, mysql_free_result() is a built-in PHP function that releases the results of your query from memory. Again, this is usually not a big deal unless you are returning large data sets from your queries, but it is always good practice to clear your results and free up the memory on your server. Here is an example of what the PHP code might look like:

//...CONNECT TO DATABASE...

$query = "SELECT * FROM employees WHERE age >= 30";
if ($result = mysql_query($query)) {
	while ($row = mysql_fetch_array($result)) {
		//...DO SOMETHING HERE...
	}
	mysql_free_result($result); //free the query results from memory
}

///...CLOSE YOUR DATABSE CONNECTION...

?But, if you have strict PHP warnings enabled on your server, you may start getting the warning above for some (but not all) of your queries. I had a really hard time tracking this problem down, but I finally found it here. You only use mysql_free_result() for the following query types: SELECT, SHOW, EXPLAIN, and DESCRIBE. So, if you perform an UPDATE query, it doesn’t return a valid resource and throws the warning when you call mysql_free_result(). Duh.