I have the following results for my database table:
The Query:
SELECT
service_titles.user_id, service_titles.slide_id, service_titles.name as title_name ,service_names.name as service_name
FROM service_names
INNER JOIN service_titles ON service_names.title_id = service_titles.id
So what needs to happen is:
If the user has 2 unique service titles, then the max number of service_names for that title will be 6
If the user has 1 service title, the the max number of service_names for that title will be 16
I will be using PHP for all of the coding, but I am wondering how I would go about this. I need a way to count how many unique service_titles there are for that user and slide, and then count how many service items there are for each title.
Thanks for any help!
SELECT COUNT(DISTINCT service_titles.name)
FROM service_names
INNER JOIN service_titles ON service_names.title_id = service_titles.id
GROUP BY service_titles.user_id, service_titles.slide_id
That'll get you the number of distinct title_names for each user_id/slide_id combo.
SELECT COUNT(DISTINCT service_names.name)
FROM service_names
INNER JOIN service_titles ON service_names.title_id = service_titles.id
GROUP BY service_titles.user_id, service_titles.slide_id
... and that's the number of distinct service_names for same. If you want both in one query, you can put both COUNTs together, since you're using the same GROUP BY regardless.
You could use a CASE statement within your query to change the max number of service_names.
See MySQL CASE statement reference
To do this in the SQL itself would be quicker than evaluating it in PHP.
To count how many distinct titles you can try:
SELECT user_id, COUNT(DISTINCT name)
FROM service_titles
GROUP BY user_id
Related
I'm kind of noobie to this, but I'm trying to learn, I have two tables, the first one (NEWS) has all the information about posts of a blog, it has the follow structure:
* NEWS (TABLE 1)
- id_new
- id_category
- date
- ...etc
- **likes**
and I have a second table:
* LIKES (TABLE 2)
- id_like
- id_new
- id_user
- date
- ip_user
So, I want to select all the rows from TABLE 1 to display all the news but also i want to count the likes and get the COUNT of each new as like column.
This approach left joins the NEWS table to a subquery which finds the number of likes for each news story.
SELECT
t1.*,
COALESCE(t2.likes, 0) AS likes
FROM NEWS t1
LEFT JOIN
(
SELECT id_new, COUNT(*) AS likes
FROM LIKES
GROUP BY id_new
) t2
ON t1.id_new = t2.id_new
Note that here a story having no likes would not appear at all in the LIKES table and would receive a count of zero. Also note that I assume that every record in the LIKES table corresponds to a logical like. If not, then the query could be modified to count something else.
You can do it like this
SELECT table1.*, table2.*, count(table2.id_like) as like FROM news AS table1
INNER JOIN likes AS table 2 ON table1.id_new = table2.id_new;
OR
SELECT table1.*, table2.*, count(table2.id_like) as like FROM news AS table1
LEFT JOIN likes AS table 2 ON table1.id_new = table2.id_new;
you can use prepared statement
for example
$stmt = $pdo->prepare("SELECT count(*) FROM TABLE_1);
$stmt2 = $pdo->prepare("SELECT count(*) FROM TABLE_2);
//then execute
just read more on prepared statement
Try this
SELECT n, (SELECT count(*) FROM like l WHERE l.id_new = n.id_new) FROM news n
Use something like :
SELECT *, (SELECT COUNT(*) FROM LIKES WHERE LIKES.id_new =id_new) AS newsLikesCount FROM NEWS ORDER BY date;
This query would return all news and their number of likes
select n1.* , numberOfLikes.number_of_likes
from news n1
left join
(select n.id_news, count(l.id_like) as number_of_likes
from news n
left join likes l on n.id_news = l.id_new
group by n.id_news) numberOfLikes on n1.id_news = numberOfLikes.id_news
The important concepts here is understanding how two tables are joined together (1), how group by works(2), and how to aggregate l.id_likes using count(3).
(1). Left join preserves everything in the NEWS table and join them
with news link to the news.
(2). Then we group the rows base on id_news from the news. However,
mysql gets confused because it doesn't know what to do with id_like
from the likes table that we included in our select clause. Don't
worry my friend, This is where count comes in.
(3). We count the number of id_likes base for each id_news since we
are grouping the rows base on id_news.
I hope this helps. and welcome to StackOverfow. If you find this answer of any other answer helpful please mark it as the solution. That way it will help the community and fellow programmers in the future if they run into the same problem as you. Cheers.
Edit: to include all columns from news table we simply join the result from above back to the news table itself. and we select everything from the news table n1 and only number_of_likes from the result we created above.
Here is
I want to show rows with same stop name one time..
How i use Query and While Loop
I see you have and id column. Assuming that it is unique you can do this all in sql query, no need for while loop.
You will need 2 queries; first will get the maximum (could be minimum also) available id of only one distinct stop name, the second is a join query with the first results and the main table. Something like this:
select * from tablename
inner join
(
select stop, max(id) as id from tablename
group by stop
)
as uniqueIDs
on tablename.id=uniqueIDs.id
u may try this..this will help you to fetch duplicates from table
SELECT tablename.stop FROM tablename INNER JOIN
(SELECT stop FROM tablename GROUP BY stop HAVING COUNT(id) > 1) dup
ON tablename.stop = dup.stop;
I have two tables:
twitterusers table
twittergrowth Table
I am trying to do JOIN these 2 tables, get all fields from twitteruser and selective fields from twittergrowth, then fetch only the last 3 rows from this data.
Expected Output:
Current Output:
I.e the rows are repeating. I want rows unique by ID or usernames, and the last set of timestamps. So it would be the last 3 rows, which has the most recent timestamps.
The code I could type scribble out is :
SELECT
t1.*,
t2.new_followers_count,
t2.new_friends_count,
t2.new_timestamp
FROM twitterusers t1
JOIN twittergrowth t2 on (t1.username=t2.username)
Searched quite few pages/sites, but cant really figure out how to do it. I would appreciate any help. :)
Additionally, I would like to get a LIMIT parameter added to the final result, so that I can paginate the full result.
First you need to find a maximum new_timestamp (latest) within groups of the same user_id and username in twittergrowth table. This is a classic group-wise maximum problem and the subquery tgmax does that. Then you need to join back the same table (tg this time) to get other columns that aren't in the group by clause of subquery and are not used in aggregate functions (like max()). These columns are new_followers_count and new_friends_count.
If you tried to put them in the select of subquery mysql would return values from an unspecified row from the same group and not necessarily the same as the one with the latest timestamp. This is explained here.
Once you get desired output for twittergrowth table the only thing left is to join twitterusers table to get all other columns.
SELECT tu.*, tg.new_followers_count, tg.new_friends_count, tg.new_timestamp
FROM twitterusers tu
JOIN twittergrowth tg
ON tu.user_id = tg.user_id AND tu.username = tg.username
JOIN
( SELECT tgg.user_id, tgg.username, max(tgg.new_timestamp) as latest_timestamp
FROM twittergrowth tgg
GROUP BY tgg.user_id, tgg.username ) tgmax
ON tg.user_id = tgmax.user_id AND tg.username = tgmax.username
AND tg.new_timestamp = tgmax.latest_timestamp
Note that this query would benefit from a composite index on (user_id,username,new_timestamp) in the twittergrowth table.
You need to group by to achieve your expected output.
GROUP BY id
To limit, or split results into pages, you can simply add LIMIT X,Y where X is the starting record and Y is the total number of records.
So a query to pull the expected results you want, but only the first 10 would be like so:
SELECT
t1.*,
t2.new_followers_count,
t2.new_friends_count,
t2.new_timestamp
FROM twitterusers t1
JOIN twittergrowth t2 on t1.username=t2.username
GROUP BY t1.id
LIMIT 0,10
I've been racking my brain for hours trying work out how to join these two queries..
My goal is to return multiple venue rows (from venues) based on certain criteria... which is what my current query does....
SELECT venues.id AS ven_id,
venues.venue_name,
venues.sub_category_id,
venues.score,
venues.lat,
venues.lng,
venues.short_description,
sub_categories.id,
sub_categories.sub_cat_name,
sub_categories.category_id,
categories.id,
categories.category_name,
((ACOS( SIN(51.44*PI()/180)*SIN(lat*PI()/180) + COS(51.44*PI()/180)*COS(lat*PI()/180)*COS((-2.60796 - lng)*PI()/180)) * 180/PI())*60 * 1.1515) AS dist
FROM venues,
sub_categories,
categories
WHERE
venues.sub_category_id = sub_categories.id
AND sub_categories.category_id = categories.id
HAVING
dist < 5
ORDER BY score DESC
LIMIT 0, 100
However, I need to include another field in this query (thumbnail), which comes from another table (venue_images). The idea is to extract one image row based on which venue it's related to and it's order. Only one image needs to be extracted however. So LIMIT 1.
I basically need to insert this query:
SELECT
venue_images.thumb_image_filename,
venue_images.image_venue_id,
venue_images.image_order
FROM venue_images
WHERE venue_images.image_venue_id = ven_id //id from above query
ORDER BY venue_images.image_order
LIMIT 1
Into my first query, and label this new field as "thumbnail".
Any help would really be appreciated. Thanks!
First of all, you could write the first query using INNER JOIN:
SELECT
...
FROM
venues INNER JOIN sub_categories ON venues.sub_category_id = sub_categories.id
INNER JOIN categories ON sub_categories.category_id = categories.id
HAVING
...
the result should be identical, but i like this one more.
What I'd like to do next is to JOIN a subquery, something like this:
...
INNER JOIN (SELECT ... FROM venue_images
WHERE venue_images.image_venue_id = ven_id //id from above query
ORDER BY venue_images.image_order
LIMIT 1) first_image
but unfortunately this subquery can't see ven_id because it is evaluated first, before the outer query (I think it's a limitation of MySql), so we can't use that and we have to find another solution. And since you are using LIMIT 1, it's not easy to rewrite the condition you need using just JOINS.
It would be easier if MySql provided a FIRST() aggregate function, but since it doesn't, we have to simulate it, see for example this question: How to fetch the first and last record of a grouped record in a MySQL query with aggregate functions?
So using this trick, you can write a query that extracts first image_id for every image_venue_id:
SELECT
image_venue_id,
SUBSTRING_INDEX(
GROUP_CONCAT(image_id order by venue_images.image_order),',',1) as first_image_id
FROM venue_images
GROUP BY image_venue_id
and this query could be integrated in your query above:
SELECT
...
FROM
venues INNER JOIN sub_categories ON venues.sub_category_id = sub_categories.id
INNER JOIN categories ON sub_categories.category_id = categories.id
INNER JOIN (the query above) first_image on first_image.image_venue_id = venues.id
INNER JOIN venue_images on first_image.first_image_id = venue_images.image_id
HAVING
...
I also added one more JOIN, to join the first image id with the actual image. I couldn't check your query but the idea is to procede like this.
Since the query is now becoming more complicated and difficult to mantain, i think it would be better to create a view that extracts the first image for every venue, and then join just the view in your query. This is just an idea. Let me know if it works or if you need any help!
I'm not too sure about your data but a JOIN with the thumbnails table and a group by on your large query would probably work.
GROUP BY venues.id
I need help with an advanced SQL-query (MSSQL 2000).
I have a table called Result that lists athletics 100 meter race-times. A runner can have several racetimes but I want to show only the best time from each runner.
The Result-table contains three columns, Result_id, athlete_id, result_time. So athlete_id must be unique when I list the values and result_time must be the fastest (lowest) value.
Any ideas?
In SQL Server 2000, you can't use windows functions. You can do this as follows:
select r.*
from result r join
(select athlete_id, min(result_time) as mintime
from result r
group by athlete_id
) rsum
on rsum.athlete_id = r.athlete_id and r.time = rsum.mintime
In more recent versions of SQL Server, you would use row_number().
If you simply need the fastest time for each athlete_id, do this:
select athelete_id, min(result_time) as FastestTime
from result
group by athelete_id
To show additional columns from the result table, you can join back to it like this:
select r.*
from result r
inner join (
select athelete_id, min(result_time) as FastestTime
from result
group by athelete_id
) rm on r.athelete_id = rm.athelete_id and r.result_time = rm.FastestTime
What you want is to use an aggregate function. in this case min() which will select the minumin data from all the rows that have the same data in the other selected columns. This means you also have to us the group by clause. The query below should give you the results you want.
Edit: If you need other columns, just bring them into the select clause, then add them to the group by clause like below:
select althlete_id, result_id, min(result_time) as result_time from result-table group by althlete_id, result_id
select althlete_id, result_id, min(result_time) as result_time, race_date from result-table group by althlete_id, race_date, result_id
Edit: You need to add all the columns into the group by that aren't part of an aggregate function. Aggregate functions are ones like min(), max(), avg() and so on.
Short answer: If you aren't putting a column in brackets, it probably has to be in the group by.