How would I combine multiple columns that could fit into the same row instead of having the same row display many times?
flight | Manager | Lead | Worker
---------------------|-----------|-------|--------
Arizona_BGS_Flight_2 | John | |
Arizona_BGS_Flight_2 | | Will |
Arizona_BGS_Flight_2 | | | James
Utah_UTS_Flight_5 | John | |
Into:
flight | Manager | Lead | Worker
---------------------|-----------|-------|--------
Arizona_BGS_Flight_2 | John | Will | James
You can use aggregation:
select flight, max(manager) as manager, max(lead) as lead, max(worker) as worker
from t
group by flight;
Related
I'm trying to merge 2 queries into 1 (cuts the number of daily queries in half): I have 2 tables, I want to do a query against 1 table, then the same query against the other table that has the same list just less entries.
Basically its a list of (let's call it for obfuscation) people and hobby. One table is ALL people & hobby, the other shorter list is people & hobby that I've met. Table 2 would all be found in table 1. Table 1 includes entries (people I have yet to meet) not found in table 2
The tables are synced up from elsewhere, what I'm looking to do is print a list of ALL people in the first column then print the hobby ONLY of people that are on both lists. That way I can see the lists merged, and track the rate at which the gap between both lists is closing. I have tried a number of SQL combinations but they either filter out the first table and match only items that are true for both (i.e. just giving me table 2) or just adding table 2 to table 1.
Example of what I'm trying to do below:
+---------+----------+--+----------+---------+--+---------+----------+
| table1 | | | table2 | | | query | |
+---------+----------+--+----------+---------+--+---------+----------+
| name | hobby | | activity | person | | name | hobby |
| bob | fishing | | fishing | bob | | bob | fishing |
| bill | vidgames | | hiking | sarah | | bill | |
| sarah | hiking | | planking | sabrina | | sarah | hiking |
| mike | cooking | | | | | mike | |
| sabrina | planking | | | | | sabrina | planking |
+---------+----------+--+----------+---------+--+---------+----------+
Normally I'd just take the few days to learn SQL a bit better however I'm stretched pretty thin at work as it is!
I should mention the table 2 is flipped and the headings are all unique (don't think this matters)!
I think you just want a left join:
select t1.name, t2.activity as hobby
from table1 t1 left join
table2 t2
on t1.name = t2.person;
Consider the following sample table("Customer") with these records
=========
Customer
=========
-----------------------------------------------------------------------------------------------
| customer-id | att-a | att-b | att-c | att-d | att-e | att-f | att-g | att-h | att-i | att-j |
--------------+-------+-------+-------+-------+-------+-------+-------+-------+-------+-------+
| customer-1 | att-a-7 | att-b-3 | att-c-10 | att-d-10 | att-e-15 | att-f-11 | att-g-2 | att-h-7 | att-i-5 | att-j-14 |
--------------+-------+-------+-------+-------+-------+-------+-------+-------+-------+-------+
| customer-2 | att-a-9 | att-b-7 | att-c-12 | att-d-4 | att-e-10 | att-f-4 | att-g-13 | att-h-4 | att-i-1 | att-j-13 |
--------------+-------+-------+-------+-------+-------+-------+-------+-------+-------+-------+
| customer-3 | att-a-10 | att-b-6 | att-c-1 | att-d-1 | att-e-13 | att-f-12 | att-g-9 | att-h-6 | att-i-7 | tt-j-4 |
--------------+-------+-------+-------+-------+-------+-------+-------+-------+-------+-------+
| customer-19 | att-a-7 | att-b-9 | att-c-13 | att-d-5 | att-e-8 | att-f-5 | att-g-12 | att-h-14 | att-i-13 | att-j-15 |
--------------+-------+-------+-------+-------+-------+-------+-------+-------+-------+-------+
I have these records and many more records dumped into SQL database and wanted to find top 10 similar customer based on the attribute value. For example customer-1 and customer-19 have atleast one column value matching .i.e "att-a-7" so the output should give me 2 customer-id's or top similar customer that are customer-1 and customer-19.
P.S - there can be one or more columns similar across rows.
I'm using windowing technique to find top 10 similar customer and im not sure if I'm correct.
following is my approach I used in my query :
row_number() over (partition by att-a, att-b,..,att-j order by customer-id) as customers
is this correct. ?
The quest is to check if one set fully includes another. As simplified example we can take four tables:
worker (id, name),
worker_skills (worker_id, skill),
job (id, type)
job_required_skills (job_id, skill)
I want to match the worker to the job but only if job required skills are fully match worker skills, i. e. if worker has some skills which are not required on job it's ok, but if job has at least one skill which worker doesn't then they don't match.
All I can think of includes ridiculous amount of joins and can't be used as a serious solution, so any advices are highly appreciated. Database is postgres 9.6. Thanks!
EDIT:
Some sample data:
+------+---------------+
| name | worker_skills |
+------+---------------+
| John | java |
| John | sql |
| John | ruby |
| Jane | js |
| Jane | html |
+------+---------------+
+---------------------+-------------+
| type | job_skills |
+---------------------+-------------+
| Writing_queries | sql |
| Writing_queries | black_magic |
| Generic_programming | java |
| Frontend_stuff | js |
| Frontend_stuff | html |
+---------------------+-------------+
Result:
+------+---------------------+
| John | Generic_programming |
+------+---------------------+
| Jane | Frontend_stuff |
+------+---------------------+
John is perfectly qualified for Generic_programming (the only needed skill is in his skillset) but can't do Writing_queries as it requires some black_magic; Jane can do Frontend_stuff as she has both required skills.
You can use a left join and aggregation:
select jrs.id, ws.id
from job_required_skills jrs left join
worker_skills ws
on jrs.skill = ws.skill
group by jrs.id, ws.id
having count(*) = count(ws.skill)
Basically, I have 3 tables, titles, providers, and provider_titles.
Let's say they look like this:
| title_id | title_name |
|------------|----------------|
| 1 | San Andres |
| 2 |Human Centipede |
| 3 | Zoolander 2 |
| 4 | Hot Pursuit |
| provider_id| provider_name |
|------------|----------------|
| 1 | Hulu |
| 2 | Netflix |
| 3 | Amazon_Prime |
| 4 | HBO_GO |
| provider_id| title_id |
|------------|----------------|
| 1 | 1 |
| 1 | 2 |
| 2 | 1 |
| 3 | 1 |
| 3 | 3 |
| 4 | 4 |
So, clearly there are titles with multiple providers, yeah? Typical many-to-many so far.
So what I'm doing to query it is with a JOIN like the following:
SELECT * FROM provider_title JOIN provider ON provider_title.provider_id = provider.provider_id JOIN title ON title.title_id = provider_title.title_id WHERE provider.name IN ('Netflix', 'HBO_GO', 'Hulu', 'Amazon_Prime')
Ok, now to the actual issue. I don't want repeated title names back, but I do want all of the providers associated with the title. Let me explain with another table. Here is what I am getting back with the current query, as is:
| provider_id| provider_name | title_id | title_name |
|------------|---------------|----------|---------------|
| 1 | Hulu | 1|San Andreas |
| 1 | Hulu | 2|Human Centipede|
| 2 | Netflix | 1|San Andreas |
| 3 | Amazon_Prime | 1|San Andreas |
| 3 | Amazon_prime | 3|Zoolander 2 |
| 4 | HBO_GO | 4|Hot Pursuit |
But what I really want would be something more like
| provider_id| provider_name |title_id| title_name|
|------------|-----------------------------|--------|-----------|
| [1, 2, 3] |[Hulu, Netflix, Amazon_Prime]| 1|San Andreas|
Meaning I only want distinct titles back, but I still want each title's associated providers. Is this only possible to do post-sql query with logic iterating through the returned rows?
Depending on your database engine, there may be an aggregation function to help achieve this.
For example, this SQLfiddle demonstrates the postgres array_agg function:
SELECT t.title_id,
t.title_name,
array_agg( p.provider_id ),
array_agg( p.provider_name )
FROM provider_title as pt
JOIN
provider as p
ON pt.provider_id = p.provider_id
JOIN title as t
ON t.title_id = pt.title_id
GROUP BY t.title_id,
t.title_name
Other database engines have equivalents. For example:
mySQL has group_concat
Oracle has listagg
sqlite has group_concat (as well!)
If your database isn't covered by the above, you can google '[Your database engine] aggregate comma delimited string'
is it possible to return count of values in single row?
For example this is test table and I want to count of daily_typing_pages
SQL> SELECT * FROM employee_tbl;
+------+------+------------+--------------------+
| id | name | work_date | daily_typing_pages |
+------+------+------------+--------------------+
| 1 | John | 2007-01-24 | 250 |
| 2 | Ram | 2007-05-27 | 220 |
| 3 | Jack | 2007-05-06 | 170 |
| 3 | Jack | 2007-04-06 | 100 |
| 4 | Jill | 2007-04-06 | 220 |
| 5 | Zara | 2007-06-06 | 300 |
| 5 | Zara | 2007-02-06 | 350 |
+------+------+------------+--------------------+
Result of this count should be : 1610 how ever if I simply count() AROUND it return:
SQL>SELECT COUNT(daily_typing_pages) FROM employee_tbl ;
+---------------------------+
| COUNT(daily_typing_pages) |
+---------------------------+
| 7 |
+---------------------------+
1 row in set (0.01 sec)
So it return number of rows instead of count single row.
Is there some way how to do things like I want without using external programming language which will count it for me?
Thanks
You want SUM instead of COUNT. COUNT merely counts the number of records, you want them summed.
You didn't mention your DBMS, but see for example, for sql server this
Did you mean you want to summarize alle numbers of daily_typing_pages ?
So you can use sum(daily_typing_pages):
SELECT SUM(daily_typing_pages) FROM employee_tbl