Given a table cycles(id int unsigned auto_increment, machine, location, ontime, offtime), new ontimes are inserts that leave offtime null, new offtime values are wrttien to the latest row with a null offtime, and your query becomes ... select sec_to_time( sum( unix_timestamp(off...
If an internal in-memory temporary table becomes too large (as determined using the tmp_table_size and max_heap_table_size system variables), MySQL automatically converts the table from in-memory to on-disk format. On-disk temporary tables use the storage engine defined by the internal_tmp_...
I assume that some of the problem is that sum_timer_event is incremented whenever the mutex is locked whether or not the thread really waited. And then this is likely made worse by any measurement code that overstates the wait time (what is the overhead for rdtsc)? But in the last mea...
Stream)(s)).ReadTimeout. What might be wrong? (407) Proxy Authentication Required. (C# console application) OR (C#windows form application) (Programatically) Restart Explorer.exe like its done with task manager [A]MySQL.Data.MySqlClient.MySqlConnection cannot be cast to [B]MySQL.Data.MySql...
Joins. mSQL can become pathologically slow if you change the order of tables in a SELECT. In the benchmark suite, a time more than 15,000 times slower than MySQL server was seen. This is due to mSQL’s lack of a join optimiser to order tables in the optimal order. However, if you...
(MySQL) .NET pdf viewer .pdb files in production environment? 'An operation was attempted on a nonexistent network connection' error 'bootstrap' is not a valid script name. The name must end in '.js'. 'Cannot implicitly convert 'System.TimeSpan' to 'System.DateTime' 'DayOfWeek' is not...
Have you ever wanted a way to see your query traffic, almost in real time, without a need to collect the data first (from slow logs or tcpdump) and then process it? Or maybe you’d like to execute graceful switchovers and failovers, as your application does not handle broken transacti...
My intention is: grab the (N)th and (N+1)th numbers, which are already in my_cte, and sum them; so: grab a row from my_cte, containing the (N)th number, and a row from my_cte, containing the (N+1)th number, and sum them; to grab the two rows ...
If you do not have the time to read hundreds of articles this multipurpose handbook may be useful. I created it in the hope that it will be useful especially for System Administrators and WebOps. I hope you enjoy it. Before you start remember about the two most important things: Do not...
Re: MySQL - How to SUM two query from different table? iqbal khan October 22, 2012 01:54AM Re: MySQL - How to SUM two query from different table? Rick James October 22, 2012 09:26PM Sorry, you can't reply to this topic. It has been closed....