I'm currently developing a system to manage students that are on a report in school but I've fallen across a stumbling block. In my SQL table ('onreport')there is a field called 'duration' I want any records where the date stored stored in this row is passed to be deleted, I.e the report has expired.
<?php
include('connect.php'); //connect to the database
$today = new DateTime("now");
$f_today=$today->format('Y-m-d');
mysql_query('DELETE FROM onreport WHERE duration ==$f_today');
//print('$f_today')
?>
I realise that this may not be the most efficient method even if it did work but I was getting desperate! I know that the code is running because including the commented out print statement prints today's correct date in the same format as the format in the table.
The duration column is type 'date' and in the table it is displayed as yyyy-mm-dd
It seems that instead of comparing dates, you are comparing string, which is generally considered a bad practice. But since you didn't post your DB schema it is hard to tell.
However if you to want to remove every report posted before today, you can use pure SQL query assuming that the field duration is of DATE type:
DELETE FROM onreport WHERE TIMESTAMPDIFF(DAY,CURDATE(),duration)>0
This queries compare two dates : CURDATE() which is the current server time with the value of duration and return a result in number of days. If this value is greater than zero, the row is removed.
Related
I've been tinkering with PHP lately (self-taught, no formal training), trying to understand how to grab data from a database and display the data somewhere. So far I have learned quite a bit, but now I am stumped.
I have a list of about 200 users in my local database in a table called site_members. The table has three fields: id, name, birth_date. Via PHP, I want to display all the users on a webpage, and have something like "Birthday soon!" be mentioned right after their name. Something like this:
John Smith (Birthday soon!)
I haven't written the code to do this, because I usually write pseudocode first before actually diving into the coding part. Here's the pseudocode:
Get the current date and time and convert it to Unix timestamp
Start foreach loop and go through list of users
Query the database table, get the birthdate of a user by their id, and store it in a variable named bdate.
Convert bdate to Unix timestamp
Subtract the current date from bdate, convert it into days remaining, and store it in a variable called remaining_days.
If the user's bdate is within 15 days (remaining_days is less than 15)
Display their name, followed by (Birthday soon!)
otherwise
Just display their name only
End if
End foreach loop
Here's my problem: With the above pseudocode once translated into actual code, there would be a database query made every time in that foreach loop. Some of the tutorials I consulted mentioned I should avoid that for efficiency reasons, and it makes sense. I ran Google searches to find something similar, but that didn't do much. I do not want anyone to write any actual code for me. I just want a better solution to the querying.
Thanks in advance!
I think your concept for the pseudo code is right, and you're understanding of doing multiple database queries is also right, you just tangled the two into giving you a wrong idea.
If you construct your select statement properly (that's basically what you'd be using to access the database), you actually pull the information for everyone out of the database and store it once in an array (or some other form of object). You can then start your foreach loop using the array as your value and perform the rest of your checks that way.
$date = date("m.d.y");
$people = ** insert your commands to grab the info from the DB **
foreach($people as $person) {
// do your comparison checks and echo's etc in here
}
Does this make sense?
There can be two solutions to your problem:-
1:
Instead of making query for every user, first get the data for all the users.
Traverse the data using foreach loop php
Do the processing and display the results.
2:
Store the user date_of_birth in proper mysql date datatype
Change your mysql query to use date function to get all the users who match your date difference criteria and just display those users.
It seems you failed to read up properly on the relationship between SQL and PHP. If you actually posted code, then you could have been easily unstumped because there are many ways to do the simple task from legacy tutorials to current PDO or even MVC within in 5mins or less.
I'm not going to write the code but you need to change HOW you think in your "pseudo code".
The problem with your pseudo code is because you believe that the DB is not smart and you are doing it as if it was only for storage.
The correct pattern for PHP is the following:
1) use the Date function to retrieve current day + 15. Get month and
day only.
2) you make a SQL query that retrieve all users who's
birth_date field's month and day are GREATER THAN (or equal) to
TODAY and who are less than or equal to today + 15 (day and month
only)
3) execute the query.
4) with the returned data set (if any)
you can choose two path depending situation and design
a) you can loop it with a simple FETCH which fetch each row retrieve
and display name and extra message.
or
b) iterates through the result set and store the display message
into a variable and then finally display it once the iteration is
done.
(option b is prefered because its more flexible since you can use this technique to out into a file instead of an echo)
THIS pseudo-code ensures that you are only retrieve the correct data set with the aid of the SQL system (or storage system).
In terms of overall process, aashnisshah is absolutely correct. First, you should retrieve all the records you need from your database then loop through each row to do your data comparisons and finally close the loop.
As for finding out if their birthday is close and if you want MySQL to do the hard work, you can build your query like that in PHP:
$query = "SELECT *, DATEDIFF(DATE_FORMAT(dob, '" . date('Y') . "-%m-%d'), CURDATE()) AS days_to_dob FROM Members";
The idea is to fetch an extra column called 'days_to_dob' containing the amount of days until that person's date of birth. Note that it will be negative if that date has passed for this year. With that extra column you can easily evaluate whether their dob is within 15 days.
If you don't want any php code, then here is my pseudocode:
Get date and time -> UTC stamp and store in $time_current
Get all from site_members and store in $data
for each entry in $data, store in $record
get birth_date from $record and convert to utc stamp and store in $birthday
print name from $record
if $birthday is close to $time_current then print "Birthday soon" end if
print new line
end for
That performs only one request to your database.
Wanted to ask You how can I setup something on my php website, that would everyday automatically check and compare current date to all the database datetime entries and delete the rows of the dates that are in the past (for ex. if the current date is 2014-03-17, it would delete the rows that have datetime of 2014-03-16 ).
Because I basically have a TV-package website (not a real thing, just for a class), where you can order a package, you enter for how long and it adds that amount to current date, writes the order into database with the date written into a field named "expires". Would it make sense if I just wrote the checking function into the index, so when someone visits the site it would delete it? If so, how could I compare the two dates?
The DB example looks something like this: http://s29.postimg.org/7sbgj2hnr/dbtest.png
Although I highly recommend a scheduled task, you can do it in PHP by calling:
$sql = "DELETE FROM tableName WHERE `expires`<'".date('Y-m-d')."'";
Convert the date to a unix timestamp and compare it against the value of time() like you would any other integers.
I'm new to MySQL and PHP but was wondering if someone could help me with a little project I'm doing for my boss.
I have a SQL database (MyDB) and a table in there (mytable) with two columns - the first column (index) is an auto-incrementing integer from 1-10, the second column (date) has different dates and timestamps in the format of Year-month-day time 2013-04-12 1326
I'm trying to create a simple PHP page that first gets the current date (easy enough) then looks at the table and shows the number of rows that fall within yesterday's date. For example, if I have 3 rows with 2013-04-11 XXXX and 2 rows with 2013-04-12 XXXX (and today is the 12th April 2013) the page will display 3. (The time is not important but we can't remove it from the table as it's auto created by one of the other staff's programs and he refuses to change it).
So far I've got my php page, done a connection to the DB and defined two variables:
$startdate = date('Y'."-".'n'."-".'d'." "."0000");
$enddate = date('Y'."-".'n'."-".'d'." "."2359");
As the timestamp doesn't matter I've gone for the min/max possible on the variables. I realise this will only give the current date, trying to work out how to get it to display the previous day as the date in the variable.
Now I'm trying to create a sql query that will count the number of rows where the date field falls within the startdate and enddate variables (-1 day) but not too sure where to start or how this would look. I then need to output this as a variable in PHP so I can echo it later in the page.
Anyone able to point me in the right direction? Hope any of this makes sense.
You could write a query with no params to do this (if its always just yesterday).
SELECT * FROM <table>
WHERE DATE_FORMAT(<date column>,'%j-%Y') = DATE_FORMAT(DATE_SUB(now(),INTERVAL 1 DAY), '%j-%Y');
Date functions in the where clause might not be super awesome performance wise
$query="update attendance
SET
`day1`='$day1', `day2`='$day2', `day3`='$day3', `day4`='$day4',
`day5`='$day5', `day6`='$day6', `day7`='$day7', `day8`='$day8',
`day9`='$day9', `day10`='$day10', `day11`='$day11', `day12`='$day12',
`day13`='$day13', `day14`='$day14', `day15`='$day15', `day16`='$day16',
`day17`='$day17', `day18`='$day18', `day19`='$day19', `day20`='$day20',
`day21`='$day21', `day22`='$day22', `day23`='$day23', `day24`='$day24',
`day25`='$day25', `day26`='$day26', `day27`='$day27', `day28`='$day28',
`day29`='$day29', `day30`='$day30', `day31`='$day31', `accident`='$a1',
`disiplinary`='$d1', `family_death`='$fd1', `family_illness`='$fi1',
`holiday`='$h1', `illness`='$i1', `jury_duty`='$j1', `leave`='$l1',
`layoff`='$lo1', `personal`='$p1', `tardy`='$t1', `vacation`='$v1'
WHERE `month`='January'";
$result=mysql_query($query);
Here the day1 value updated (value as 1), next to update the value day2 is 1,
in that time the day2 value is updated(1), but day1 value changed to zero.
What i do?
The way you phrased your query, all the variables like $day1 have to be set inside PHP. If they are not, then an empty string gets pasted into the request, which in turn gets converted to zeros by the MySQL server.
So if you only want to modify day2, then do just that:
UPDATE attendance SET day2 = ? WHERE month = 'January'
That said, there are a number of ways how you could improve your current approach.
You should not use mysql_query as it is deprecated.
You should not directly include variables into the query, as this opens the door to both bugs and SQL injection vulnerabilities. Use placeholders like ? instead, and provide the actual values when executing this query.
Having one column for every day looks like a pretty bad database schema. Instead have a single table with one row for each day. You can compute monthly overviews from that for your output, but in general such a request will be far easier to handle on the DB level. If you want some columns per month, you could have those in an extra table.
You probably should use the DATE type to describe each day, along the lines just described. If you really have to have a table with one row per month, then you might still use a DATE to describe it, using the first day of the month to identify the whole month. This will allow you to easily use date and time functions on that column. If you want separate year and month columns, I guess I'd still identify the month by number, not name.
I'll explain my goal first: I want the user to query the database, and return rows only if those rows have been updated since their last query. No sense returning data they'd already have. So I created a column called 'lastupdated', a timestamp type which autoupdates every time any content in the row is updated. This works fine. Now, I want to form the query correctly. The user will have their previous query's timestamp saved, and via php will use it to compare their previous query's time with the time each row has been updated. If the row was updated after their last query, the row should be returned.
I made something like this,
SELECT * FROM users WHERE '2011-02-26 01:50:30' <= lastupdated
but its obviously much too simple. I checked the MySQL manual and found this page MySQL Time/Date Page. I'm sure the answer is here, but I've read through it any nothing really makes sense. I have a timestamp in the same format used by the MySQL timestamp type, but I don't know how I will compare them. Thank you very much for your help.
That query is exactly how you'd do it. As long as a stringified date-time is in MySQL's preferred format (yyyy-mm-dd hh:mm:ss), then it will be internally converted into a datetime value, and the comparisons will go ahead.
You'd only need the date/time functions you found if you want to do something more complicated than simple "greater/less than/equal" type comparison, e.g. "any records that have a December timestamp".
As Marc said, your code should work. But you probably want to do this programmatically with a variable for the time instead of the literal.
If you don't have the date-time specified as a string, but rather as a timestamp (e.g. from using the php time() function), then you can use the following query:
$query = "SELECT * FROM users WHERE FROM_UNIXTIME(" . $timestamp . ") <= lastupdated";
The key is the FROM_UNIXTIME() MySQL function.