Storing stuff in php

Hexxx

I have a database (mysql) to do and have to perform queries for each day over a period of time and calculate station ratings.

The problem is I can only do it for one day at a time and I am a bit confused as to where the results are stored when they are returned in the php.

I currently have them stored in a multidimensional array, but does this array exist in the .php results page alone? If I want to do for multiple days/queries, what would I have to do? Write out each array to a file on disk and keep writing and adding to find an average for all the days?

NogDog

It's hard to be sure of the best approach without understanding the detailed requirements. With that caveat, probably the solution I would pursue would be to include a date or datetime column in the database table(s) involved. Then you could just use one database query using a GROUP BY expression on the date so that the results are grouped by date (and possibly using functions such as COUNT() and AVG() that work with grouped results in SQL).

If that's not a feasible approach, then I would create a table in the database to store the results of your daily queries (obviously you'd want a date or datetime field as part of that table to record when the results were saved). Then your daily script might run the first query, store the results in an array, then take those results and insert them into this new table.

Hexxx

I have a datetime field in the sql table, but because I have to first generate hourly ratings for a channel, I had to select data for only one date, and one hour at a time, Because the hourly share needs to have all the viewer ids, I had to group by tvstations and couldn't (or didn't know how to) merge all that information into one query, even using subqueries. So I ended up finding the share for a station for each hour properly, but only for a specific (single) date.

I think I would take your advice on storing the results in the table (somewhere, I would now have to revise the schema) and try to incoporate that new table in running the query for multiple days.

But I would still like to know are arrays created in a volatile manner 'in' the php page... ? meaning that if I store something in an array and then refresh the page, would it overwrite it, or is there anyway to make the array static?

NogDog

An array only exists until either the script finishes running or the array is explicitly unset() within the script, whichever comes first. You could have it persist for some period of time within the $_SESSION array if you are using sessions, but even that is normally only temporary for some fixed time limit. For anything more permanent, you'd probably be best off storing the data in your database.

Hexxx

what limits the maximum size an array can be? because I would be loading many rows from SQL and storing them in an array in PHP for further processing.

NogDog

Hexxx wrote:
what limits the maximum size an array can be? because I would be loading many rows from SQL and storing them in an array in PHP for further processing.

Mainly the memory_limit setting (if set).