I am trying to find all of the skills a every user doesn't have for a position.
I know this is incorrect, but I can't think of a way to make this work.
This is what I'm trying to do:
select id, count(skillcode)
from person p, (
select skillcode from requires_skill where poscode='1'
minus
select skillcode from hasskill where id=p.id)
group by p.id;
The part that isn't working is id=p.id.
I am using Oracle SQL.
Edit:
These are the sample tables
requires_skill
------------------
poscode | skillcode
-------------------
1 | 2
1 | 3
1 | 4
hasskill
--------------------
id | skillcode
--------------------
1 | 2
2 | 2
2 | 3
Expected output:
id | count(skillcode)
--------------------------
1 | 2
2 | 1
You can use scalar subquery like this
select id, (select count(1) from requires_skill) - cnt from (select id, count(1) cnt from hasskill group by id);
It works as long as there is foreign key relation ship between requires_skill and hasskill.
I think you need to JOIN the person and hasskill tables and use NOT EXISTS instead of MINUS.
Something like,
SELECT p.ID,
COUNT(h.skillcode)
FROM person p
JOIN hasskill h
ON p.ID = h.ID
WHERE NOT EXISTS
( SELECT skillcode FROM requires_skill WHERE poscode='1'
)
GROUP BY p.ID;
UPDATE
Regarding your question about the JOIN, you need to use an ALIAS for the sub-query.
For example,
WITH DATA AS
( SELECT skillcode FROM requires_skill WHERE poscode='1'
MINUS
SELECT skillcode FROM hasskill h, person p WHERE h.ID=p.ID
)
SELECT p.ID,
COUNT(a.skillcode)
FROM person p
JOIN data A
ON a.skillcode = p.skillcode
GROUP BY p.ID;
Related
I have a table RESTAURANT:
Id | Name
------------------
0 | 'McDonalds'
1 | 'Burger King'
2 | 'Starbucks'
3 | 'Pans'
And a table ORDER:
Id | ResId | Client
--------------------
0 | 1 | 'Peter'
1 | 2 | 'John'
2 | 2 | 'Peter'
Where 'ResId' is a foreign key from RESTAURANT.Id.
I want to select the number of order per restaurant:
Expected result:
Restaurant | Number of orders
----------------------------------
'McDonalds' | 0
'Burguer King' | 1
'Starbucks' | 2
'Pans' | 0
Actual result:
Restaurant | Number of orders
----------------------------------
'McDonalds' | 0
'Burguer King' | 1
'Starbucks' | 2
Command used:
select r.Name, count(o.ResId)
from RESTAURANT r
left join ORDER o on r.Id like o.ResId
group by o.ResId;
Just fix the group by clause:
select r.name, count(*) as cnt_orders
from restaurants r
left join orders o on r.id = o.resid
group by r.id, r.name;
That way, the SELECT and GROUP BY clauses are consistent; I also added the restaurant id to the group, so potential restaurants having the same name are not aggregated together. I also changed like to =: this is more efficient, and does not alter the logic.
You could also phrase this with a subquery, so there is no need for outer aggregation. I would prefer:
select r.*,
(select count(*) from orders o where o.resid = r.id) as cnt_orders
from restaurants r
Your query should be generating an error because the select columns and the group by columns are incompatible. Just aggregate by the unaggregated columns in the select:
select r.Name, count(o.ResId)
from RESTAURANT r left join
ORDER o
on r.Id = o.ResId
group by r.Name;
Notes:
You might want to include r.id in the GROUP BY (and SELECT) in case restaurants can have the same name.
Note the use of = instead of LIKE. The ids look like numbers, so you should use number operations. LIKE is a string operation.
ORDER is a bad name for a table because it is a SQL keyword.
As a general rule, in a LEFT JOIN, you don't want the aggregation keys to be from the second table, because those values could be NULL.
I'm having a mind lapse on what I believe is a relatively easy script. Hopefully I'm overthinking the logic.
What I'm trying to do is perform two counts on a distinct column which is right joined.
What I want is:
count(a.book_id) as count_of_books
count(b.book_ref_number) as count_of_losses
Expected Output
--------------------------------------------------------
| Book | count_of_books | count of losses|
--------------------------------------------------------
|Hunger Games | 76 | 31 |
--------------------------------------------------------
|Hop on Pop | 27 | 6 |
--------------------------------------------------------
|Pout Pout Fish | 138 | 43 |
--------------------------------------------------------
I have tried a couple different scripts. Here are the two scripts I've tried.
(select count(*) from Inventory_Table x ) Count1,
(select count(*) from Loss_table b ) Count2
from Inventory_Table x
right join Loss_table b on b.book_ref_number = x.book_id
where rownum < 20
select
a.book_name,
count(distinct a.book_id),
count(b.book_ref_number)
from Inventory_Table x
right join Loss_table b on trim(b.book_ref_number) = trim(a.book_id)
Results I get
--------------------------------------------------------
| Book | count_of_books | count of losses|
--------------------------------------------------------
|Moby Dick | 4376 | 2574 |
--------------------------------------------------------
I'm looking for guidance in my neglectful mistake. Thank you in advance
and rownum <20 doesn't make sense. you are limiting your result set with 20 records.
try this:
select * from (
select
a.mrch_Nr,
count(distinct a.fdr_trac_nr),
count(b.auth_id)
from DATASTORE_FD.DEB_CRD_AUTH_LOG_REC a
right join jordab26.ft b on trim(b.auth_id) = trim(a.fdr_trac_nr)
where a.auth_log_dt between '20200101' and '20200408'
group by a.mrch_nr
)
where rownum < 20
Try this, I'm not sure about rownum < 20. Also, make sure your add correct group by condition.
select sum(case book_id when null then 0 else 1 end ) count_of_books,
sum(case book_ref_number when null then 0 else 1 end ) count_of_losses
from Inventory_Table x
right join Loss_table b on b.book_ref_number = x.book_id
where rownum < 20
Is this what you want?
Select distinct bookname,
count(distinct
a.bookid)+sum(
case when a.bookid IS NULL
THEN 1 END) ,
count(distinct b.id) as lossid
From inventary_table a
Left Join
Loss_table b
On
a.bookid=b.book_ref_number
SELECT book_name,COUNT(book_id),COUNT(book_ref_id) FROM Inventory_Table right join Loss_table on book_ref_number = book_id GROUP BY book_name
But if you need all the books in Inventory and only matching books from Loss_table then it should be left join:
SELECT book_name,COUNT(book_id),COUNT(book_ref_id) FROM Inventory_Table leftjoin Loss_table on book_ref_number = book_id GROUP BY book_name
0
SELECT book_name,COUNT(book_id),COUNT(book_ref_id)
FROM Inventory_Table
right join Loss_table on book_ref_number = book_id GROUP BY book_name
The PostgreSQL database has two tables: user_properties and properties. The properties table contains a list of all possible properties with ids (a dictionary). The user_properties table contains what properties a user has, referencing property id from the properties table.
The properties table:
----------------------
prop_id | prop_name
----------------------
1 | Email
----------------------
2 | Phone number
----------------------
3 | Something else 1
----------------------
4 | Something else 2
----------------------
The user_properties table:
--------------------------------
user_id | prop_id | prop_value
--------------------------------
100 | 1 | asd#zxc.com
--------------------------------
100 | 2 | 1234567
--------------------------------
100 | 2 | 2345678
--------------------------------
101 | 3 | *******
--------------------------------
101 | 3 | +++++++
--------------------------------
I need to know which properties are missing for every user_id.
The expected result should look like:
-----------------------
user_id | missing_prop_id
-----------------------
100 | 3
-----------------------
100 | 4
-----------------------
101 | 1
-----------------------
101 | 2
-----------------------
101 | 4
-----------------------
You can use except as :
with properties(prop_id,prop_name) as
(
values(1, 'Email'),(2, 'Phone number'),
(3, 'Something else 1'),(4, 'Something else 2')
), user_properties( user_id, prop_id, prop_value) as
(
values(100,1,'asd#zxc.com'),(100,2,'1234567'),(100,2,'2345678'),
(101,3,'*******'),(101,3,'+++++++')
), t2 as
(
select u.user_id, p.prop_id as missing_prop_id
from user_properties u
cross join properties p
group by u.user_id, p.prop_id
except
select u.user_id,
p.prop_id
from user_properties u
right join properties p
on u.prop_id = p.prop_id
group by u.user_id, p.prop_id
)
select * from t2 order by user_id, missing_prop_id;
user_id missing_prop_id
100 3
100 4
101 1
101 2
101 4
Demo
You can simply solve this by join...
SELECT DISTINCT t3.user_id, t3.prop_id FROM
(SELECT DISTINCT user_id, t2.prop_id FROM user_properties t1, properties t2) t3
LEFT JOIN user_properties t4 ON t3.user_id = t4.user_id and t3.prop_id = t4.prop_id WHERE t4.prop_id is null
http://sqlfiddle.com/#!17/0f4e3/2/0
You can use a cross join to generate all the rows and left join to filter out the ones that don't exist:
select u.user_id, p.prop_id
from (select distinct user_id from user_properties
) u cross join
properties p left join
user_properties up
on up.user_id = u.user_id and
up.prop_id = p.prop_id
where up.user_id is null;
Presumably, you have a users table so the subquery for u is not needed:
select u.user_id, p.prop_id
from users u cross join
properties p left join
user_properties up
on up.user_id = u.user_id and
up.prop_id = p.prop_id
where up.user_id is null;
Thanks everyone for the help. I've come up with the following query myself:
select mp.user_id, mp.prop_id missing_prop_id from
(select distinct up.user_id, p.prop_id from user_properties up cross join properties p) mp
except
select distinct user_id, prop_id from user_properties
http://sqlfiddle.com/#!17/0f4e3/3/0
if I have tables
Person: ID_Person, Name
Profession: ID_Prof, Prof_Name, ID_Person
If ID_Person appears multiple times in second table and I want to show all Person names with number of their professions how can I do this?
I know that if I want to count something I can write
SELECT ID_Person, count(*) as c
FROM Profession
GROUP BY ID_Person;
but don't know how to link it with column from other table in order to proper values.
Here is one way (MySQL InnoDB)
Person
+-----------+-------+
| ID_Person | Name |
+-----------+-------+
| 1 | bob |
| 2 | alice |
+-----------+-------+
Profession
+---------+--------------------+-----------+
| ID_Prof | Prof_Name | ID_Person |
+---------+--------------------+-----------+
| 1 | janitor | 1 |
| 2 | cook | 1 |
| 3 | computer scientist | 2 |
| 4 | home maker | 2 |
| 7 | astronaut | 2 |
+---------+--------------------+-----------+
select Name, count(Prof_Name)
from Person left join Profession
on (Person.ID_Person=Profession.ID_Person)
group by Name;
+-------+------------------+
| Name | count(Prof_Name) |
+-------+------------------+
| alice | 3 |
| bob | 2 |
+-------+------------------+
Hope this helps.
To just show those with multiple Profession then you would join the two tables, and aggregate with count() using group by and filter using having():
select pe.ID_Person, pe.Name, count(*) as ProfessionCount
from Person pe
inner join Profession pr
on pe.ID_Person = pr.ID_Person
group by pe.ID_Person, pe.Name
having count(*)>1
If you want to show the professions for those people as well:
select
multi.ID_Person
, multi.Name
, multi.ProfessionCount
, prof.ID_Prof
, prof.Prof_Name
from (
select pe.ID_Person, pe.Name, count(*) as ProfessionCount
from Person pe
inner join Profession pr
on pe.ID_Person = pr.ID_Person
group by pe.ID_Person, pe.Name
having count(*)>1
) multi
inner join Profession prof
on multi.ID_Person = prof.ID_Person
you can probably try something like this below. However, you will have to think about whether or not you need to left join versus inner join. You would want to left join if there is potentially someone who has not had any professions and therefore does not exist in the professions table.
SELECT pe.Name
, Professions = COUNT(pr.Prof_Name)
FROM dbo.Person (NOLOCK) pe
JOIN dbo.Profession (NOLOCK) pr ON pe.ID_Person = pr.ID_Person
GROUP BY pe.Name
You're looking for something like this I believe. The left join will bring in all the data and won't exclude any users.
The join can also be a inner join. Inner join would then only show users that exist in both tables.
LEFT
select x.ID_Person, count(x.ID_Person) as [count] from table1 x
left join table2 y on y.ID_Person= x.ID_Person
where x.ID_Person <> null
group by x.ID_Person
INNER
select x.ID_Person, count(y.ID_Person) from table1 x
inner join table2 y on y.ID_Person= x.ID_Person
group by x.ID_Person
The easiest solution is probably counting in a subquery:
select
id_person,
name,
(select count(*) from profession pr where pr.id_person = p.id_person) as profession_count
from person p;
You can achieve the same with an outer join:
select
p.id_person,
p.name,
coalesce(pr.cnt, 0) as profession_count
from person p
left join (select id_person, count(*) as cnt from profession group by id_person) pr
on pr.id_person = p.id_person;
It's usually a good idea to aggregate before joining. Anyway, this is how to join first and aggregate then:
select
p.id_person,
p.name,
coalesce(count(pr.id_person), 0) as profession_count
from person p
left join profession pr on pr.id_person = p.id_person
group by p.id_person, p.name;
As per standard SQL it would suffice to group by p.id_person, as the name functionally depends on the id (i.e. the id uniquely defines a person, so it's one single name belonging to it). Some DBMS however don't fully comply with the standard here and demand you to either put the name in the group by clause as shown or dummy-aggregate it in the select clause (e.g. max(p.name)) instead.
Firstly, I apologize for my English. I want get auctions with count of bids and buys. It should look like this:
id | name | bids | buys
-----------------------
1 | Foo | 4 | 1
2 | Bar | 0 | 0
I have tables like following:
auction:
id | name
---------
1 | Foo
2 | Bar
auction_bid:
id | auction_id
---------------
1 | 1
2 | 1
3 | 1
4 | 1
auction_buy:
id | auction_id
---------------
1 | 1
I can get numbers in two queries:
SELECT *, COUNT(abid.id) AS `bids` FROM `auction` `t` LEFT JOIN auction_bid abid ON (t.id = abid.auction) GROUP BY t.id
SELECT *, COUNT(abuy.id) AS `buys` FROM `auction` `t` LEFT JOIN auction_buy abuy ON (t.id = abuy.auction) GROUP BY t.id
But when i combined it into one:
SELECT *, COUNT(abid.id) AS `bids`, COUNT(abuy.id) AS `buys` FROM `auction` `t` LEFT JOIN auction_bid abid ON (t.id = abid.auction) LEFT JOIN auction_buy abuy ON (t.id = abuy.auction) GROUP BY t.id
It was returning wrong amount (bids as much as buys).
How to fix this and get counts in one query?
You'll need to count DISTINCT abuy and abid IDs to eliminate the duplicates;
SELECT t.id, t.name,
COUNT(DISTINCT abid.id) `bids`,
COUNT(DISTINCT abuy.id) `buys`
FROM `auction` `t`
LEFT JOIN auction_bid abid ON t.id = abid.auction_id
LEFT JOIN auction_buy abuy ON t.id = abuy.auction_id
GROUP BY t.id, t.name;
An SQLfiddle to test with.
Try this:
SELECT t.*,COUNT(abid.id) as bids,buys
FROM auction t LEFT JOIN
auction_bid abid ON t.id = abid.auction_id LEFT JOIN
(SELECT t.id, Count(abuy.id) as buys
FROM auction t LEFT JOIN
auction_buy abuy ON t.id = abuy.auction_id
GROUP BY t.id) Temp ON t.id=Temp.id
GROUP BY t.id
Result:
ID NAME BIDS BUYS
1 Foo 2 0
2 Bar 1 1
Result in SQL Fiddle.