I have two tables as follows:
docs
id
carid
name
1
1
doc1
2
1
doc2
3
2
doc3
4
1
doc4
5
5
doc5
cars
carid
parentid
name
1
4
car1
2
5
car2
3
4
car3
4
4
car4
5
5
car5
Question: I want to write a query in mysql where I can pass the carid in where clause and get all the rows from docs table where the parentid is same as that of the passed carid.
Desired Outcome If I pass carid=3 then the rows 1,2,4 from docs table should be returned as the parentid is 4 for carids 1,3,4.
Simillarly, If I pass carid=2 then the rows 3,5 from docs table should be returned as the parentid is 5 for carids 2.5.
You need to join the cars-table twice. First for the condition and second for the parent:
select d.*
from cars c
join cars p on p.parentid=c.parentid
join docs d on d.carid=p.carid
where c.carid=3
You're thinking about this a little wrong in the aspect of a relational database .. You SHOULD have 4 tables:
docs
doc_id
name
1
doc1
2
doc2
3
doc3
4
doc4
5
doc5
cars
car_id
name
1
car1
2
car2
3
car3
4
car4
5
car5
cars_to_docs
car_id
doc_id
1
1
1
2
1
4
2
3
5
5
parents_to_car
car_id
parent_id
1
4
2
5
3
4
4
4
5
5
Then you could simply use a basic JOIN
SELECT b.doc_id FROM test.docs a
LEFT JOIN test.cars_to_docs b
ON a.doc_id = b.car_id
LEFT JOIN test.parents_to_car c
ON c.car_id = b.car_id
LEFT JOIN test.cars d
ON c.car_id = d.car_id
WHERE c.parent_id = (SELECT parent_id FROM test.parents_to_car WHERE car_id = 3)
This will give you your output of 1,2,4
Related
i have table structure like this
id
user_id
parent_id
club
1
1
club1
2
2
1
club1
3
3
1
club1
4
4
2
club1
5
5
2
club1
6
6
3
club1
7
7
3
club1
8
8
4
club1
9
9
4
club1
10
10
5
club1
11
11
5
club1
12
12
6
club1
13
13
6
club1
14
14
7
club1
15
15
7
club1
i want to select user_id whose child is less then 2.
refer to above table user 1,2,3,4,5,6 and 7 two child complete so the query should return 8,9,10,11,12,13,14,15
Refer to above table here user_id 1 have two child 2 and 3 , user_id 2 have child 4 and 5 and so on.
i need to select user_id whose child is less than 2
You can do it as follows :
SELECT user_id
FROM club_tree
WHERE user_id NOT IN (
SELECT parent_id
from club_tree
where club = 'club1'
group by parent_id
HAVING count(1) >= 2
)
and club = 'club1';
We Select users that are not in the list of users with more than two childs.
This is to get users with more than two childs :
SELECT parent_id
from club_tree
group by parent_id
HAVING count(1) >= 2
Here you can test it : http://sqlfiddle.com/#!9/eb2c70/3
Can you try this query using left join :
SELECT c.user_id
from club_tree c
left join
(
select parent_id
from club_tree
where club = 'club1'
group by parent_id
HAVING count(1) >= 2
) as c2 on c.user_id = c2.parent_id
where c.club = 'club1' and c2.parent_id is null;
Try it here : http://sqlfiddle.com/#!9/eb2c70/17
please provide query to getting my result.
i have two tables as follows.
price_band
id club_id name price
1 6 test 2.3
2 6 test1 3.3
price_band_seat
id price_band_id row seat block_id
1 1 a 1 1
2 1 a 2 1
3 1 b 1 2
4 2 b 2 2
and result that i want
Price block_id price_band_id row
2.3 1 1 a
2.3 2 1 b
3.3 2 2 b
query exclude that raw which block_id and price_band_id are same . in where clues you have to take club_id=6
Please try this.
SELECT
DISTINCT
A.Price,B.block_id,B.price_band_id,B.row
FROM
price_band A
INNER JOIN price_band_seat B
ON A.id = B.price_band_id
WHERE A.club_id = 6
I am stuck in query I have a table like this
budget_details
id budget_id expenditure_head_id budget
1 1 1 1233
2 1 2 333
3 1 3 567
4 2 1 343
5 2 2 343
6 2 3 6767
7 2 4 557
expenditure_heads
id name
1 abc
2 xyz
3 qwe
4 uvw
I want to get all the expenditure_heads from budget_details that even
if not in budget_details like here budget_id=1 does not contain expenditure_head_id 4
but I want to select that to with 0 or null displaying
I tried this but it not displaying expenditure_head_id 4
select `expenditure_heads`.`name`, `budget_details`.`budget`, `budget_details`.`id` from
`budget_details`
right join `expenditure_heads` on `budget_details`.`expenditure_head_id` = `expenditure_heads`.`id`
where `budget_details`.`budget_id` = 1"
The where avoid you to get the missing row you need. The left join is done on the ON statement, so this query should work for you:
SELECT EH.name, BD.budget, BD.id FROM expenditure_heads EH
LEFT JOIN budget_details BD
ON (BD.expenditure_head_id = EH.id AND BD.budget_id = 1)
I have this table:
ID STUDENT CLASS QUESTION ANSWER TIME
1 1 1 1 c 12:30
2 1 1 1 d 12:36
3 1 1 2 a 12:38
4 2 1 1 b 11:24
5 2 1 1 c 11:26
6 2 1 3 d 11:35
7 2 3 3 b 11:24
I'm trying to write a query that does this:
For each STUDENT in a specific CLASS select the most recent ANSWER for each QUESTION.
So, choosing class "1" would return:
ID STUDENT CLASS QUESTION ANSWER TIME
2 1 1 1 d 12:36
3 1 1 2 a 12:38
5 2 1 1 c 11:26
6 2 1 3 d 11:35
I've tried various combinations of subqueries, joins, and grouping, but nothing is working. Any ideas?
You can use a sub-query to get most recent ANSWER per QUESTION, Then use this as a derived table and join back to the original table:
SELECT m.*
FROM mytable AS m
INNER JOIN (
SELECT STUDENT, QUESTION, MAX(`TIME`) AS mTime
FROM mytable
WHERE CLASS = 1
GROUP BY STUDENT, QUESTION
) AS d ON m.STUDENT = d.STUDENT AND m.QUESTION = d.QUESTION AND m.`TIME` = d.mTime
WHERE m.CLASS = 1
Demo here
I want to retrieve table with total count from multiple table and joins
I have 4 wordpress custom database tables.
wp_tutorials
ID tut_name
1 php
2 mysql
3 wordpress
wp_chapters
ID tut_id chapter_name
1 1 php1
2 1 php2
3 2 mysql1
4 2 mysql2
wp_series
ID chapter_id series_name
1 1 php1A
2 1 php1B
3 2 php2A
4 2 php2B
5 3 mysql1A
6 3 mysql1B
7 4 mysql2A
8 4 mysql2B
wp_tut_users
ID series_id user_name
1 2 user1
2 2 user2
3 4 user3
4 6 user4
5 7 user5
from these four tables I want to retrieve by sql query following table.
1. tutorial
tut_name total_users
php 3
mysql 2
wordpress 0
expecting best ways...
Use a left join to get even tutorials with no users
select t.tut_name, count(u.id) as total_users
from wp_tutorials t
left join wp_chapters c on c.tut_id = t.id
left join wp_series s on s.chapter_id = c.id
left join wp_tut_users u on u.series_id = s.id
group by t.tut_name