I have models Book and BookCategory
How do I select the cheapest book in every category?
Book table:
| id | name | price | book_category_id |
| 1 | test | 10 | 1
| 2 | test | 15 | 3
| 3 | test | 75 | 1
| 4 | test | 25 | 2
| 5 | test | 19 | 1
| 6 | test | 11 | 2
| 7 | test | 10 | 1
The selection should be :
| id | name | price | book_category_id |
| 1 | test | 10 | 1
| 2 | test | 15 | 3
| 6 | test | 11 | 2
I've tried:
$books = Book::groupBy("book_category_id")->orderBy("price")->get()
But the output is not the minimum price row.
any idea?
EDIT:
I found this page:
https://www.xaprb.com/blog/2006/12/07/how-to-select-the-firstleastmax-row-per-group-in-sql/
it has 90% of the solution in SQL
SELECT *
FROM books
WHERE price = (SELECT MIN(price) FROM books AS u WHERE u.book_category_id= books.book_category_id)
GROUP BY books.book_category_id
how to convert this to laravel query builder?
You need to perform a subquery like this post. Try this:
$books = Book::from(DB::raw("SELECT * FROM books order by price asc"))
->groupBy("book_category_id")->get();
Please note that this is a mysql only solution because in mysql you're allowed to not aggregate non-group-by columns. If you need to do this for another DB, you need to perform an inner join on the subquery
Related
First, I've checked other topics on the subject like this one How to transpose/pivot data in hive? but that doesn't match with what I want.
So this is the table I have
| ID | Day | Status |
| 1 | 1 | A |
| 2 | 10 | B |
| 3 | 101 | A |
| 3 | 322 | B |
| 3 | 102 | C |
| 3 | 354 | D |
And i'd like to concat the different Status for each IDs ordering by the Day, in order to have this :
| ID | Status |
| 1 | A |
| 2 | B |
| 3 | A,C,B,D |
The thing is that I don't know how many status I can have, so i can't create as many columns I want for the days since I don't know how many day/status I'll have, so the answers from other topics with group_map or others, I don't know how to adapt it for my problem.
Thank's for helping me ^^
use collect_set (for distinct values) or collect_list to aggregate array and concatenate it using concat_ws:
select ID, concat_ws(',',collect_list(Status)) as Status
from table
group by ID;
I have two tables 'locations' and 'markets', where, a many to many relationship exists between these two tables on the column 'market_id'. A report level filter has been applied on the column 'entity' from 'locations' table. Now, I'm supposed to distinctly count the 'location_id' from 'markets' table where 'active=TRUE'. How can I write a DAX query such that the distinct count of location_id dynamically changes with respect to the selection made in the report level filter?
Below is an example of the tables:
locations:
| location_id | market_id | entity | active |
|-------------|-----------|--------|--------|
| 1 | 10 | nyc | true |
| 2 | 20 | alaska | true |
| 2 | 20 | alaska | true |
| 2 | 30 | miami | false |
| 3 | 40 | dallas | true |
markets:
| location_id | market_id | active |
|-------------|-----------|--------|
| 2 | 20 | true |
| 2 | 20 | true |
| 5 | 20 | true |
| 6 | 20 | false |
I'm fairly new to powerbi. Any help will be appreciated.
Here you go:
DistinctLocations = CALCULATE(DISTINCTCOUNT(markets[location_id]), markets[active] = TRUE())
We have a table which we record our students' attendances in. We need to find out which students missed n number of contacts in a row.
Here is the attendance table structure with example records
----------------------------------------------------
| id | student_id | class_id | checkedin_time |
--------------------------------------------------
| 1 | 1 | 1 | null |
| 2 | 1 | 2 | 2019-07-09 10:30 |
| 3 | 1 | 3 | null |
| 4 | 1 | 4 | null |
| 5 | 1 | 5 | 2019-07-12 12:00 |
----------------------------------------------------
What I'm looking for is a code that show me records with id 3 and 4 (two subsequent missed contacts) grouped by student_id
This was my starting point:
$attendances = \App\Attendance::where('checked_time' , null)->get();
$attendances->groupBy('student_id')
Hi I want query from 3 table
user:
+----+-----------+
| id | name |
+----+-----------+
| 1 | Denny |
| 2 | Agus |
| 3 | Dini |
| 4 | Angel |
+----+-----------+
History_Education
+----+-----------+-------------+
| id | userId | educationId |
+----+-----------+-------------+
| 1 | 1 | 1 |
| 2 | 1 | 2 |
| 3 | 2 | 1 |
| 4 | 2 | 2 |
+----+-----------+-------------+
Education
+----+-----------+----------+
| id | level | Name |
+----+-----------+----------+
| 1 | 1 | SD |
| 2 | 2 | SMP |
| 3 | 3 | SMA |
| 4 | 4 | S1 |
+----+-----------+----------+
How to query with laravel Eloquent to get the latest user education order by Level DESC
expected:
+----+-----------+----------------------+
| id | Name | Latest_Education |
+----+-----------+----------------------+
| 1 | Denny | SMP |
| 2 | Agus | SMP |
| 3 | Dini | - |
| 4 | Angel | - |
+----+-----------+----------------------+
In normal query:
select id,name ,(select E.name from education E inner join History_eductaion HE on E.id = HE.education_id where HE.userId =U.id limit 1 order by E.level DESC )latest_education from USER U
How to translate to laravel eloquent?
The quick answer is use the query builder - your query needed to be altered slightly to match the table names and columns as listed in your question:
$result = DB::table('user')
->select([
'id',
'name',
DB::raw("(select E.name from Education E inner join History_Education HE on E.id = HE.educationId where HE.userId = user.id order by E.level DESC limit 1) as latest_education")
])
->get();
Assume a range of values inserted in a schema table and in the end of the month i want to apply for these records (i.e. 2500 rows = numeric values) the algorithm: sort the values descending (from the smallest to highest value) and then find the 80% value of the sorted column.
In my example, if each row increases by one starting from 1, the 80% value will be the 2000 row=value (=2500-2500*20/100). This algorithm needs to be implemented in a procedure where the number of rows is not constant, for example it can varries from 2500 to 1,000,000 per month
Hint: You can achieve this using Oracle's cumulative aggregate functions. For example, suppose your table looks like this:
MY_TABLE
+-----+----------+
| ID | QUANTITY |
+-----+----------+
| A | 1 |
| B | 2 |
| C | 3 |
| D | 4 |
| E | 5 |
| F | 6 |
| G | 7 |
| H | 8 |
| I | 9 |
| J | 10 |
+-----+----------+
At each row, you can sum the quantities so far using this:
SELECT
id,
quantity,
SUM(quantity)
OVER (ORDER BY quantity ROWS UNBOUNDED PRECEDING)
AS cumulative_quantity_so_far
FROM
MY_TABLE
Giving you:
+-----+----------+----------------------------+
| ID | QUANTITY | CUMULATIVE_QUANTITY_SO_FAR |
+-----+----------+----------------------------+
| A | 1 | 1 |
| B | 2 | 3 |
| C | 3 | 6 |
| D | 4 | 10 |
| E | 5 | 15 |
| F | 6 | 21 |
| G | 7 | 28 |
| H | 8 | 36 |
| I | 9 | 45 |
| J | 10 | 55 |
+-----+----------+----------------------------+
Hopefully this will help in your work.
Write a query using the percentile_disc function to solve your problem. Sounds like it does what you want.
An example would be
select percentile_disc(0.8) within group (order by the_value)
from my_table