I have 2 tables I want to connect in a strange / dangerous / non-dynamic way. I don't have control over these tables. I'm trying to pull the summary from one table that contains event id but not category id but I need to reference another table to make sure that said event is in said category. This table contains both event id and cat id. I'm trying to join them but I keep getting returned nothing.
I know this is dangerous, but I also have control over the categories so I know that my category ID's will not change unless I specify. Since it auto-increments - my categories will be 1, 2, 3.
The Gist of my Tables
*events_vevent*
- ev_id
- catid
---
*events_vevdetail*
- evdet_id
- summary
My Code
$data = array();
for($i = 0; $i < 3; $i++){
$summary = array();
$query_summary = mysql_query("SELECT events_vevdetail.summary FROM
events_vevdetail, events_vevent
WHERE 'events_vevent.evdet_id = $i' LIMIT 5")
or die(mysql_error());
while(($row = mysql_fetch_array($query_summary)))
$summary[] = $row[0];
switch($i){
case 0:
$data['cat1'] = $summary;
break;
case 1:
$data['cat2'] = $summary;
break;
case 2:
$data['cat3'] = $summary;
break;
}
}
echo json_encode($data);
Explanation
so what I'm trying to do is: Since I know category 1 will always have an ID of 0, I want to pull the most recent 5 posts, but only posts in category ID 0. Same for cateogry2 and 3. Right now I'm getting empty arrays. I feel like I need 2 mysql queries (one for each table) and then compare but I'm not 100% sure and would rather do this the right way than the long way.
tl;dr is my MYSQL right?
This query will return top most 5 records from each category.
SELECT e1 . *
FROM events_vevent e1
LEFT OUTER JOIN events_vevent e2 ON
( e1.catid = e2.catid AND e1.ev_id < e2.ev_id )
GROUP BY e1.ev_id
HAVING COUNT( * ) < 5
ORDER BY catid, ev_id DESC
Related
I have a Part Management system I've created in PHP with MySQL. What I'm trying to create is something that will generate the next Part Number for me. All part numbers start with a 3 letter prefix (which is determined by the product family/category) followed by their number.
For example 'ABC001'
What I have below is something that I'd like to use to determine what the next number is having already 'ABC001', 'ABC002' & 'ABC003' so I would like it to recognize what the next number is by querying until the query comes back false because that product number doesn't exist yet.
$abc_query = "SELECT * FROM products WHERE id LIKE 'ABC%'";
$abc_result = $mysqli2->query($abc_query);
while($row = $abc_result->fetch_assoc()) {
$rowid = $row["id"];
$pnumber = substr($rowid, 3, 3);
echo $pnumber. '<br/>';
$int = (int)$pnumber;
$abc_query2 = "SELECT * FROM products WHERE id 'ABC" . sprintf('%03s', $int);
for ($abc_query2 = true; $abc_query2 = false; $int++){
echo $int;
}$abc_nextnumber = $int +1;
}
$abc_newnumber = 'ABC' . sprintf('%03s', $abc_nextnumber);
echo $abc_newnumber;
The result I get is
001
002
003
005
ABC006
However the result should be..
001
002
003
ABC004
code update I've updated the code but it doesn't seem to stop at ABC004 if I have an 005. It will go to 006.
You should have the db do this instead of your app:
select t.id_prfx, max(t.id_num) as latest_num from
(select substring(id, 1, 3) as id_prfx,
cast(substring(id,4) as integer) as id_num) t
group by id_prfx
This will give you a result table where you get the highest part number for each prefix.
If you really really only want prefixes of 'ABC' then:
select max(cast(substring(id,4) as integer)) as max_num from table
where id LIKE 'ABC%'
Could you try this query?
SELECT MAX(SUBSTR(id, 4)) as last_id FROM products WHERE SUBSTR(id, 1, 3)='ABC'
EDİT:
products TABLE
==============
ABC001
ABC002
ABC003
ABC005
==============
We want to find 4 in products table.
SELECT SUBSTR(t1.id, 4) + 1 as POSSIBLE_MIN_ID
FROM products t1
WHERE NOT EXISTS (
SELECT *
FROM products t2
WHERE SUBSTR(id, 1, 3)='ABC' AND SUBSTR(t2.id, 4) = SUBSTR(t1.id, 4) + 1
) LIMIT 1
RESULT:
POSSIBLE_MIN_ID : 4
If anyone knows how I can have it add automatic zeros to the into the query (as it will be different amount of 0s once it gets to 'ABC011') instead of typing them in that would also be very helpful.
Here's how to automatically handle the prepended zeroes.
$sql3 = "SELECT * FROM products WHERE id 'ABC" . sprintf('%03s', $int);
I'm trying to display and sort an array by an average created using data from a database. I'm retrieving three variables from the database and creating an average from these values. This value is then placed inside a new array to be sorted along with the rest of the database data.
Am I right in thinking that having the SQL query inside the loop isn't a great idea? (Performance issue?)
Is there any alternative that's available? I've attached the code below:
^ database connection/query string to retrieve all data...
$result = $stmt_business_list->fetchAll(PDO::FETCH_ASSOC);
$items = array();
foreach($result as $row){
$single_business_id = $row['id'];
$name = $row['name'];
//Query to get ALL the service, value and quality ratings for certain business
$test_query = "SELECT * FROM rating WHERE business_id = $single_business_id";
$test_query_stmt = $dbh->prepare($test_query);
$test_query_stmt->execute();
$test_row = $test_query_stmt->fetchAll(PDO::FETCH_ASSOC);
$total_value = $total_quality = $total_service = 0;
foreach($test_row as $review)
{
$total_value += $review['value'];
$total_quality += $review['quality'];
$total_service += $review['service'];
}
$bayesian_value = (($set_site_average_review_count * $set_site_average_review_score) + $total_value) / ($set_site_average_review_count + $business_review_count);
$bayesian_quality = (($set_site_average_review_count * $set_site_average_review_score) + $total_quality) / ($set_site_average_review_count + $business_review_count);
$bayesian_service = (($set_site_average_review_count * $set_site_average_review_score) + $total_service) / ($set_site_average_review_count + $business_review_count);
$average_bayesian_rating = ($bayesian_value + $bayesian_quality + $bayesian_service) / 3;
$average_bayesian_rating = $average_bayesian_rating;
array_push($items, array(
"id"=>"$single_business_id",
"name"=>"$name",
"value"=>"$total_value",
"quality"=>"$total_quality",
"service"=>"$total_service",
"average"=>"$average_bayesian_rating"));
echo
'Name: '.$name.'<br>
Value: '.$total_value.'<br>
Quality: '.$total_quality.'<br>
Service: '.$total_service.'<br>
Average: '.$average_bayesian_rating.'<br><br>';
}
}
The page will be split up by a separate pagination script and will only display 6 objects at a time, but over time this may change so I do have an eye on performance as much as I can.
SQL aggregate queries are made for this kind of thing.
Use this query to summarize the results
SELECT b.name, b.id,
SUM(value) total_value,
SUM(quality) total_quality,
SUM(service) total_service,
COUNT(*) review_count,
avg_reviews_per_biz
FROM business b
JOIN ratings r ON b.id = r.business_id
JOIN (
SELECT COUNT(DISTINCT business_id) / COUNT(*) avg_reviews_per_biz
FROM ratings
) a ON 1=1
GROUP BY b.name, b.id, avg_review_per_biz
This will give you one row per business showing the summed ratings and the number of ratings. This result set will have the following columns
name business name
id business id
total_value sum of value ratings for that business
total_quality sum of quality ditto
total_service sum of service ditto
review_count number of reviews for business "id"
avg_reviews_per_biz avg number of reviews per business
The last column has the same value for all rows of your query.
You can then loop over these row one business at a time doing your statistical computations.
I can't tell from your question where you're getting variables like $set_site_average_review_count, so I can't help with those computations.
You'll find that SQL aggregate querying is very powerful indeed.
I have mysql table that looks like this:
id place interest
1 place1 a,b,c
2 place2 c,d,e
3 place1 a,e
4 place2 f
5 place2 f
6 place3 g,h
I need to get unique "place" and "interest" values sorted as per the count.
So, the output for "place" would be
place2(3)
place1(2)
place3(1)
So, the output for "interest" would be
a(2)
c(2)
e(2)
f(2)
b(1)
d(1)
g(1)
h(1)
is there a way to do this in PHP-Mysql?
So, far I have been able to get simple column data
SELECT place,
COUNT( * ) AS num
FROM testtab
GROUP BY place
ORDER BY COUNT( * ) DESC
As mysql is not able to hold arrays, its better to build a new table like this:
interest_id interest_name
1 a
2 b
and another one to keep the relations:
pk id interest_id
1 1 1
2 1 2
which this id is the id of the records in your main table.
With having this, you can easily use:
select count(*) from THIRD_TABLE where id = YOUR_ID
You can do this.
$place = array();
$interests = array();
foreach($rows as $row){
if (!isset($place[$row["place"]])){
$place[$row["place"]] = 0;
}
$place[$row["place"]]++;
$ints = explode(",", $row["interests"]);
foreach($ints as $int){
if (!isset($interests[$int])){
$interests[$int] = 0;
}
$interests[$int]++;
}
}
This will give you the two arrays keyed off of the relevant field with the value being the count. If this is going to be a common action in your application it would make more sense to normalize your data as suggested by AliBZ.
This is for the first result you need
SELECT place,COUNT(interest)
FROM `testtab`
GROUP by place
ORDER BY COUNT(interest) desc
can do this :
$inst_row = '';
foreach($rows as $row){
$inst_row .= $row['interests'];
}
$inst_values = explode(',', $inst_row);
$inst_count = array_count_values($inst_values);
// $inst_count will return you count as you want ,print_r it and format it accordingly
Ok, so I have some MySQL tables as follows:
Buildings
Building-ID Building-Name
===========----=============
1 Building-1
2 Building-2
3 Building-3
4 Building-4
Building-1
Mroom State
=====----======
1 Booked
2 Empty
3 Empty
4 Empty
Building-2
Mroom State
=====----======
1 Booked
2 Empty
3 Empty
4 Empty
And a query in PHP as follows (Ignore the hard coded while, I've simplified the code a bit):
$sql = "select * from Buildings";
$result = mysql_query ($sql) or die(mysql_error());
while ($row = mysql_fetch_array($result))
{
$building[] = $row['ward_name'];
}
$v1 = 0;
while ($v1 < 4)
{
$sql = "SELECT COUNT(*) FROM `$building[$v1]` WHERE state = 'Empty'";
$result = mysql_query($sql) or die(mysql_error());
$count = mysql_result($result, 00);
var_dump($count[$v1]);
$v1 = $v1 + 1;
}
To my way of thinking this should create an array of the buildings contained in the "Buildings" table, start a loop, load the building name from the array and provide a row count for the table of how many rows contain "Empty" in the state column. What it actually does is provide a count for the first table and then provides "NULL" for the rest.
I'd appreciate any help you can give me.
Cheers!
What about changing your data model?
Table buldings can be kept as is:
Buildings
Building-ID Building-Name
===========----=============
1 Building-1
2 Building-2
3 Building-3
4 Building-4
New table:
Rooms
Building-ID Mroom State
===========-=====-=====
1 1 1
1 2 0
2 1 0
State 0 = Empty, State 1 = Booked
Then use a join with group by:
select count(*) from buildings b inner join rooms r on r.bid = b.id where r.state = 0 group by b.id;
Then you will get a row for each building with the count of empty rooms. You won't need a table for each building.
This does noit make sense:
$count = mysql_result($result, 00);
var_dump($count[$v1]);
you mean to write:
$count[$v1] = mysql_result($result, 00);
var_dump($count[$v1]);
Also do not use several tables with names matching columns of other tables.
You can use one table with a primary key that spans two columns instead, for example create primary key on($buildingid,$roomid)
so that the table has columns $buildingid,$roomid, and $state.
mysql_result() returns a string, not an array.
Modify the code and check that now it works as expected.
var_dump($count);
i have this code:
while ($sum<16 || $sum>18){
$totala = 0;
$totalb = 0;
$totalc = 0;
$ranka = mysql_query("SELECT duration FROM table WHERE rank=1 ORDER BY rand() LIMIT 1");
$rankb = mysql_query("SELECT duration FROM table WHERE rank=2 ORDER BY rand() LIMIT 1");
$rankc = mysql_query("SELECT duration FROM table WHERE rank=3 ORDER BY rand() LIMIT 1");
while ($rowa = mysql_fetch_array($ranka)) {
echo $rowa['duration'] . "<br/>";
$totala = $totala + $rowa['duration'];
}
while ($rowb = mysql_fetch_array($rankb)) {
$totalb = $totalb + $rowb['duration'];
}
while ($rowc = mysql_fetch_array($rankc)) {
$totalc = $totalc + $rowc['duration'];
}
$sum=$totala+$totalb+$totalc;
}
echo $sum;
It works fine, But the problem is until "$sum=16" the "echo $rowa['duration']" executes, the question is, is there a away to "echo" only the latest executed code in the "while ($rowa = mysql_fetch_array($ranka))" i this while loop?
Because most of the times returns all the numbers until the "$sum=16"
You are explicitly echoing the $rowa['duration'] in the first inner while loop. If you only want to print the last duration from the $ranka set, simple change the echo to $rowa_duration = $rowa['duration'] then echo it outside the loop.
while ($rowa = mysql_fetch_array($ranka)) {
$rowa_duration = $rowa['duration'];
$totala = $totala + $rowa['duration'];
}
echo $rowa_duration . '<br/>';
What you are doing there is bad on multiple levels. And your english horrid. Well .. practice makes perfect. You could try joining ##php chat room on FreeNode server. That would improve both your english and php skills .. it sure helped me a lot. Anyway ..
The SQL
First of all, to use ORDER BY RAND() is extremely ignorant (at best). As your tables begin the get larger, this operation will make your queries slower. It has n * log2(n) complexity, which means that selecting querying table with 1000 entries will take ~3000 times longer then querying table with 10 entries.
To learn more about it , you should read this blog post, but as for your current queries , the solution would look like:
SELECT duration
FROM table
JOIN (SELECT CEIL(RAND()*(SELECT MAX(id) FROM table)) AS id) as choice
WHERE
table.id >= choice.id
rank = 1
LIMIT 1
This would select random duration from the table.
But since you you are actually selecting data with 3 different ranks ( 1, 2 and 3 ), it would make sense to create a UNION of three queries :
SELECT duration
FROM table
JOIN (SELECT CEIL(RAND()*(SELECT MAX(id) FROM table)) AS id) as choice
WHERE
table.id >= choice.id
rank = 1
LIMIT 1
UNION ALL
SELECT duration
FROM table
JOIN (SELECT CEIL(RAND()*(SELECT MAX(id) FROM table)) AS id) as choice
WHERE
table.id >= choice.id
rank = 2
LIMIT 1
UNION ALL
SELECT duration
FROM table
JOIN (SELECT CEIL(RAND()*(SELECT MAX(id) FROM table)) AS id) as choice
WHERE
table.id >= choice.id
rank = 3
LIMIT 1
Look scary, but it actually will be faster then what you are currently using, and the result will be three entries from duration column.
PHP with SQL
You are still using the old mysql_* functions to access database. This form of API is more then 10 years old and should not be used, when writing new code. The old functions are not maintained (fixed and/or improved ) anymore and even community has begun the process of deprecating said functions.
Instead you should be using either PDO or MySQLi. Which one to use depends on your personal preferences and what is actually available to you. I prefer PDO (because of named parameters and support for other RDBMS), but that's somewhat subjective choice.
Other issue with you php/mysql code is that you seem to pointlessly loop thought items. Your queries have LIMIT 1, which means that there will be only one row. No point in making a loop.
There is potential for endless loop if maximum value for duration is 1. At the start of loop you will have $sum === 15 which fits the first while condition. And at the end that loop you can have $sum === 18 , which satisfies the second loop condition ... and then it is off to the infinity and your SQL server chokes.
And if you are using fractions for duration, then the total value of 3 new results needs to be even smaller. Just over 2. Start with 15.99 , ends with 18.01 (that's additional 2.02 in duration or less the 0.7 per each). Again .. endless loop.
Suggestion
Here is how i would do it:
$pdo = new PDO('mysql:dbname=my_db;host=localhost', 'username', 'password');
$pdo->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
$sum = 0;
while ( $sum < 16 )
{
$query = 'that LARGE query above';
$statement = $pdo->prepare( $query );
if ( $statement->execute() )
{
$data = $statement->fetchAll( PDO::FETCH_ASSOC );
$sum += $data[0]['duration']+$data[1]['duration']+$data[2]['duration'];
}
}
echo $data[0]['duration'];
This should do what your code did .. or at least, what i assume, was your intentions.