问题
I execute MySQL queries from PHP and would like to know how time consuming they are. Is there any way to get the execution time of a MySQL query from PHP?
I also wonder if the execution time depends on how loaded is the web server. I can imagine that a query will take more time to execute if the server is busy with other queries. On the other hand, I can imagine that, if the server is busy, the query will just wait for its turn and then it will be executed (without any queries executed in parallel) and than the waiting time is not included into the execution time. So, what scenarios (out of two) is correct?
回答1:
There is probably some way to do this via MySQL, however, the easy (and reliable) way is using PHP's microtime function, which returns the current time as milliseconds.
microtime() returns the current Unix timestamp with microseconds. This function is only > available on operating systems that support the gettimeofday() system call.
getasfloat - When called without the optional argument, this function returns the string "msec sec" where sec is the current time measured in the number of seconds since the Unix Epoch (0:00:00 January 1, 1970 GMT), and msec is the microseconds part. Both portions of the string are returned in units of seconds.
If the optional get_as_float is set to TRUE then a float (in seconds) is returned.
Some example code:
$sql = '...';
$msc = microtime(true);
mysql_query($sql);
$msc = microtime(true)-$msc;
echo $msc . ' s'; // in seconds
echo ($msc * 1000) . ' ms'; // in millseconds
回答2:
microtime() takes time to execute itself. If you want to get the data straight from mysql, do this...
mysql_query("SET profiling = 1;");
if (mysql_errno()) { die( "ERROR ".mysql_errno($link) . ": " . mysql_error($link) ); }
$query="SELECT some_field_name FROM some_table_name";
$result = mysql_query($query);
if (mysql_errno()) { die( "ERROR ".mysql_errno($link) . ": " . mysql_error($link) ); }
$exec_time_result=mysql_query("SELECT query_id, SUM(duration) FROM information_schema.profiling GROUP BY query_id ORDER BY query_id DESC LIMIT 1;");
if (mysql_errno()) { die( "ERROR ".mysql_errno($link) . ": " . mysql_error($link) ); }
$exec_time_row = mysql_fetch_array($exec_time_result);
echo "<p>Query executed in ".$exec_time_row[1].' seconds';
回答3:
To get it right out of MySQL you can use the general log.
If its not already on, turn it on:
SET GLOBAL general_log = 'ON';
To see the data after you've run your query:
SELECT * FROM mysql.general_log;
Among other things, you will get the query execution time, just like you've probably seen in phpmyadmin.
来源：https://stackoverflow.com/questions/4501876/how-to-get-the-execution-time-of-a-mysql-query-from-php