I have Car table. Car has is_sold and is_shipped. A Car belongs to a dealership, dealership_id (FK).
I want to run a query that tells me the count of sold cars and the count of shipped cars for a given dealership all in one result.
sold_count | shipped_count
10 | 4
The single queries I have look like this:
select count(*) as sold_count
from car
where dealership_id=25 and is_sold=true;
and
select count(*) as shipped_count
from car
where dealership_id=25 and is_shipped=true;
How do I combine the two to get both counts in one result?
This will do:
select dealership_id,
sum(case when is_sold is true then 1 else 0 end),
sum(case when is_shipped is true then 1 else 0 end)
from cars group by dealership_id;
You can use the filter clause of the Aggregate function. (see demo)
select dealership_id
, count(*) filter (where is_sold) cars_sold
, count(*) filter (where is_shipped) cars_shipped
from cars
where dealership_id = 25
group by dealership_id;
You can also using cross join.
select 'hello' as col1, 'world' as col2;
return:
col1 | col2
-------+-------
hello | world
(1 row)
similarly,
with a as
(
select count(*) as a1 from emp where empid> 5),
b as (
select count(*) as a2 from emp where salary > 6000)
select * from a, b;
or you can even apply to different table. like:
with a as
(select count(*) as a1 from emp where empid> 5),
b as
(select count(*) as a2 from ab )
select * from a, b;
with a as
(
select count(*) as sold_count
from car
where dealership_id=25 and is_sold=true
),
b as
(
select count(*) as shipped_count
from car
where dealership_id=25 and is_shipped=true
)
select a,b;
further reading: https://www.postgresql.org/docs/current/queries-table-expressions.html.
https://stackoverflow.com/a/26369295/15603477
Related
I have table with self-related foreign keys and can not get how I can receive firs child or descendant which meet condition. My_table structure is:
id
parent_id
type
1
null
union
2
1
group
3
2
group
4
3
depart
5
1
depart
6
5
unit
7
1
unit
I should for id 1 (union) receive all direct child or first descendant, excluding all groups between first descendant and union. So in this example as result I should receive:
id
type
4
depart
5
depart
7
unit
id 4 because it's connected to union through group with id 3 and group with id 2 and id 5 because it's connected directly to union.
I've tried to write recursive query with condition for recursive part: when parent_id = 1 or parent_type = 'depart' but it doesn't lead to expected result
with recursive cte AS (
select b.id, p.type_id
from my_table b
join my_table p on p.id = b.parent_id
where b.id = 1
union
select c.id, cte.type_id
from my_table c
join cte on cte.id = c.parent_id
where c.parent_id = 1 or cte.type_id = 'group'
)
Here's my interpretation:
if type='group', then id and parent_id are considered in the same group
id#1 and id#2 are in the same group, they're equals
id#2 and id#3 are in the same group, they're equals
id#1, id#2 and id#3 are in the same group
If the above is correct, you want to get all the first descendent of id#1's group. The way to do that:
Get all the ids in the same group with id#1
Get all the first descendants of the above group (type not in ('union', 'group'))
with recursive cte_group as (
select 1 as id
union all
select m.id
from my_table m
join cte_group g
on m.parent_id = g.id
and m.type = 'group')
select mt.id,
mt.type
from my_table mt
join cte_group cg
on mt.parent_id = cg.id
and mt.type not in ('union','group');
Result:
id|type |
--+------+
4|depart|
5|depart|
7|unit |
Sounds like you want to start with the row of id 1, then get its children, and continue recursively on rows of type group. To do that, use
WITH RECURSIVE tree AS (
SELECT b.id, b.type, TRUE AS skip
FROM my_table b
WHERE id = 1
UNION ALL
SELECT c.id, c.type, (c.type = 'group') AS skip
FROM my_table c
JOIN tree p ON c.parent_id = p.id AND p.skip
)
SELECT id, type
FROM tree
WHERE NOT skip
I have a table with people and another with visits. I want to count all visits but if the person signed up with 'emp' or 'oth' on ref_signup then remove the first visit. Example:
This are my tables:
PEOPLE:
id | ref_signup
---------------------
20 | emp
30 | oth
23 | fri
VISITS
id | date
-------------------------
20 | 10-01-2019
20 | 10-05-2019
23 | 10-09-2019
23 | 10-10-2019
30 | 09-10-2019
30 | 10-07-2019
On this example the visit count should be 4 because persons with id's 20 and 30 have their ref_signup as emp or oth, so it should exclude their first visit, but count from the second and forward.
This is what I have as a query:
SELECT COUNT(*) as visit_count FROM visits
LEFT JOIN people ON people.id = visits.people_id
WHERE visits.group_id = 1
Would using a case on the count help on this case as I just want to remove one visit not all of the visits from the person.
Subtract from COUNT(*) the distinct number of person.ids with person.ref_signup IN ('emp', 'oth'):
SELECT
COUNT(*) -
COUNT(DISTINCT CASE WHEN p.ref_signup IN ('emp', 'oth') THEN p.id END) as visit_count
FROM visits v LEFT JOIN people p
ON p.id = v.id
See the demo.
Result:
| visit_count |
| ----------- |
| 4 |
Note: this code and demo fiddle use the column names of your sample data.
Premise, select the count of visits from each person, along with a synthetic column that contains a 1 if the referral was from emp or oth, a 0 otherwise. Select the sum of the count minus the sum of that column.
SELECT SUM(count) - SUM(ignore_first) FROM (SELECT COUNT(*) as count, CASE WHEN ref_signup in ('emp', 'oth') THEN 1 ELSE 0 END as ignore_first as visit_count FROM visits
LEFT JOIN people ON people.id = visits.people_id
WHERE visits.group_id = 1 GROUP BY id) a
where's "people_id" in your example ?
SELECT COUNT(*) as visit_count
FROM visits v
JOIN people p ON p.id = v.people_id
WHERE p.ref_signup IN ('emp','oth');
then remove the first visit.
You cannot select count and delete the first visit at same time.
DELETE FROM visits
WHERE id IN (
SELECT id
FROM visits v
JOIN people p ON p.id = v.people_id
WHERE p.ref_signup IN ('emp','oth')
ORDER BY v.id
LIMIT 1
);
edit: typos
First, I create the tables
create table people (id int primary key, ref_signup varchar(3));
insert into people (id, ref_signup) values (20, 'emp'), (30, 'oth'), (23, 'fri');
create table visits (people_id int not null, visit_date date not null);
insert into visits (people_id, visit_date) values (20, '10-01-2019'), (20, '10-05-2019'), (23, '10-09-2019'), (23, '10-10-2019'), (30, '09-10-2019'), (30, '10-07-2019');
You can use the row_number() window function to mark which visit is "visit number one":
select
*,
row_number() over (partition by people_id order by visit_date) as visit_num
from people
join visits
on people.id = visits.people_id
Once you have that, you can do another query on those results, and use the filter clause to count up the correct rows that match the condition where visit_num > 1 or ref_signup = 'fri':
-- wrap the first query in a WITH clause
with joined_visits as (
select
*,
row_number() over (partition by people_id order by visit_date) as visit_num
from people
join visits
on people.id = visits.people_id
)
select count(1) filter (where visit_num > 1 or ref_signup = 'fri')
from joined_visits;
-- First get the corrected counts for all users
WITH grouped_visits AS (
SELECT
COUNT(visits.*) -
CASE WHEN people.ref_signup IN ('emp', 'oth') THEN 1 ELSE 0 END
AS visit_count
FROM visits
INNER JOIN people ON (people.id = visits.id)
GROUP BY people.id, people.ref_signup
)
-- Then sum them
SELECT SUM(visit_count)
FROM grouped_visits;
This should give you the result you're looking for.
On a side note, I can't help but think clever use of a window function could do this in a single shot without the CTE.
EDIT: No, it can't since window functions run after needed WHERE and GROUP BY and HAVING clauses.
I'm trying to perform recursive cte with postgres but I can't wrap my head around it. In terms of performance issue there are only 50 items in TABLE 1 so this shouldn't be an issue.
TABLE 1 (expense):
id | parent_id | name
------------------------------
1 | null | A
2 | null | B
3 | 1 | C
4 | 1 | D
TABLE 2 (expense_amount):
ref_id | amount
-------------------------------
3 | 500
4 | 200
Expected Result:
id, name, amount
-------------------------------
1 | A | 700
2 | B | 0
3 | C | 500
4 | D | 200
Query
WITH RECURSIVE cte AS (
SELECT
expenses.id,
name,
parent_id,
expense_amount.total
FROM expenses
WHERE expenses.parent_id IS NULL
LEFT JOIN expense_amount ON expense_amount.expense_id = expenses.id
UNION ALL
SELECT
expenses.id,
expenses.name,
expenses.parent_id,
expense_amount.total
FROM cte
JOIN expenses ON expenses.parent_id = cte.id
LEFT JOIN expense_amount ON expense_amount.expense_id = expenses.id
)
SELECT
id,
SUM(amount)
FROM cte
GROUP BY 1
ORDER BY 1
Results
id | sum
--------------------
1 | null
2 | null
3 | 500
4 | 200
You can do a conditional sum() for only the root row:
with recursive tree as (
select id, parent_id, name, id as root_id
from expense
where parent_id is null
union all
select c.id, c.parent_id, c.name, p.root_id
from expense c
join tree p on c.parent_id = p.id
)
select e.id,
e.name,
e.root_id,
case
when e.id = e.root_id then sum(ea.amount) over (partition by root_id)
else amount
end as amount
from tree e
left join expense_amount ea on e.id = ea.ref_id
order by id;
I prefer doing the recursive part first, then join the related tables to the result of the recursive query, but you could do the join to the expense_amount also inside the CTE.
Online example: http://rextester.com/TGQUX53703
However, the above only aggregates on the top-level parent, not for any intermediate non-leaf rows.
If you want to see intermediate aggregates as well, this gets a bit more complicated (and is probably not very scalable for large results, but you said your tables aren't that big)
with recursive tree as (
select id, parent_id, name, 1 as level, concat('/', id) as path, null::numeric as amount
from expense
where parent_id is null
union all
select c.id, c.parent_id, c.name, p.level + 1, concat(p.path, '/', c.id), ea.amount
from expense c
join tree p on c.parent_id = p.id
left join expense_amount ea on ea.ref_id = c.id
)
select e.id,
lpad(' ', (e.level - 1) * 2, ' ')||e.name as name,
e.amount as element_amount,
(select sum(amount)
from tree t
where t.path like e.path||'%') as sub_tree_amount,
e.path
from tree e
order by path;
Online example: http://rextester.com/MCE96740
The query builds up a path of all IDs belonging to a (sub)tree and then uses a scalar sub-select to get all child rows belonging to a node. That sub-select is what will make this quite slow as soon as the result of the recursive query can't be kept in memory.
I used the level column to create a "visual" display of the tree structure - this helps me debugging the statement and understanding the result better. If you need the real name of an element in your program you would obviously only use e.name instead of pre-pending it with blanks.
I could not get your query to work for some reason. Here's my attempt that works for the particular table you provided (parent-child, no grandchild) without recursion. SQL Fiddle
--- step 1: get parent-child data together
with parent_child as(
select t.*, amount
from
(select e.id, f.name as name,
coalesce(f.name, e.name) as pname
from expense e
left join expense f
on e.parent_id = f.id) t
left join expense_amount ea
on ea.ref_id = t.id
)
--- final step is to group by id, name
select id, pname, sum(amount)
from
(-- step 2: group by parent name and find corresponding amount
-- returns A, B
select e.id, t.pname, t.amount
from expense e
join (select pname, sum(amount) as amount
from parent_child
group by 1) t
on t.pname = e.name
-- step 3: to get C, D we union and get corresponding columns
-- results in all rows and corresponding value
union
select id, name, amount
from expense e
left join expense_amount ea
on e.id = ea.ref_id
) t
group by 1, 2
order by 1;
I have a query
SELECT id_anything FROM table1 JOIN table2 USING (id_tables)
Now, i have a situation which is:
If that join returns two rows from table2 i want to show the id_anything from table1 (1 row only)
and if the join from table2 returns 1 row, i want to show id_anything from table2.
Ps: id_anything from table 2 returns different values
Example data:
table1
id_tables | id_anything
1 | 1
table2
id_tables | id_anything
1 | 10
1 | 100
Return expected: 1
First, get the value you may want to return and the basis for deciding which to return together into one row.
SELECT table1.id_tables, table1.id_anything AS table1_id, MIN(table2.id_anything) AS table2_id, COUNT(*)
FROM table1 JOIN table2 USING (id_tables)
GROUP BY table1.id_tables, table1.id_anything
The aggregate function you use doesn't really matter since you'll only be using the value if there is only one.
You can then pick the relevant value:
WITH join_summary AS (
SELECT table1.id_tables, table1.id_anything AS table1_id, MIN(table2.id_anything) AS table2_id, COUNT(*) AS match_count
FROM table1 JOIN table2 USING (id_tables)
GROUP BY table1.id_tables, table1.id_anything
)
SELECT id_tables, CASE WHEN (match_count > 1) THEN table1_id ELSE table2_id END AS id_anything
FROM join_summary
I have following table
ID | Group | Type | Product
1 Dairy Milk Fresh Milk
2 Dairy Butter Butter Cream
3 Beverage Coke Coca cola
4 Beverage Diet Dew
5 Beverage Juice Fresh Juice
I need following output/query result:
ID | Group | Type | Product
1 Dairy
1 Milk Fresh Milk
2 Butter Butter Cream
2 Beverage
1 Coke Coca cola
2 Diet Dew
3 Juice Fresh Juice
For above sample a hard coded script can do the job but I look for a dynamic script for any number of groups. I do not have any idea how it can be done so, I do not have a sample query yet. I need ideas, examples that at least give me an idea. PIVOT looks a close option but does not looks to be fully fit for this case.
Here's a possible way. It basically unions the "Group-Headers" and the "Group-Items". The difficulty was to order them correctly.
WITH CTE AS
(
SELECT ID,[Group],Type,Product,
ROW_NUMBER() OVER (PARTITION BY [Group] Order By ID)AS RN
FROM Drink
)
SELECT ID,[Group],Type,Product
FROM(
SELECT RN AS ID,[Group],[Id]AS OriginalId,'' As Type,'' As Product, 0 AS RN, 'Group' As RowType
FROM CTE WHERE RN = 1
UNION ALL
SELECT RN AS ID,'' AS [Group],[Id]AS OriginalId,Type,Product, RN, 'Item' As RowType
FROM CTE
)X
ORDER BY OriginalId ASC
, CASE WHEN RowType='Group' THEN 0 ELSE 1 END ASC
, RN ASC
Here's a demo-fiddle: http://sqlfiddle.com/#!6/ed6ca/2/0
A slightly simplified approach:
With Groups As
(
Select Distinct Min(Id) As Id, [Group], '' As [Type], '' As Product
From dbo.Source
Group By [Group]
)
Select Coalesce(Cast(Z.Id As varchar(10)),'') As Id
, Coalesce(Z.[Group],'') As [Group]
, Z.[Type], Z.Product
From (
Select Id As Sort, Id, [Group], [Type], Product
From Groups
Union All
Select G.Id, Null, Null, S.[Type], S.Product
From dbo.Source As S
Join Groups As G
On G.[Group] = S.[Group]
) As Z
Order By Sort
It should be noted that the use of Coalesce is purely for aesthetic reasons. You could simply return null in these cases.
SQL Fiddle
And an approach with ROW_NUMBER:
IF OBJECT_ID('dbo.grouprows') IS NOT NULL DROP TABLE dbo.grouprows;
CREATE TABLE dbo.grouprows(
ID INT,
Grp NVARCHAR(MAX),
Type NVARCHAR(MAX),
Product NVARCHAR(MAX)
);
INSERT INTO dbo.grouprows VALUES
(1,'Dairy','Milk','Fresh Milk'),
(2,'Dairy','Butter','Butter Cream'),
(3,'Beverage','Coke','Coca cola'),
(4,'Beverage','Diet','Dew'),
(5,'Beverage','Juice','Fresh Juice');
SELECT
CASE WHEN gg = 0 THEN dr1 END GrpId,
CASE WHEN gg = 1 THEN rn1 END TypeId,
ISNULL(Grp,'')Grp,
CASE WHEN gg = 1 THEN Type ELSE '' END Type,
CASE WHEN gg = 1 THEN Product ELSE '' END Product
FROM(
SELECT *,
DENSE_RANK()OVER(ORDER BY Grp DESC) dr1
FROM(
SELECT *,
ROW_NUMBER()OVER(PARTITION BY Grp ORDER BY type,gg) rn1,
ROW_NUMBER()OVER(ORDER BY type,gg) rn0
FROM(
SELECT Grp,Type,Product, GROUPING(Grp) gg, GROUPING(type) tg FROM dbo.grouprows
GROUP BY Product, Type, Grp
WITH ROLLUP
)X1
WHERE tg = 0
)X2
WHERE gg=1 OR rn1 = 1
)X3
ORDER BY rn0