I have a table A that contains tree columns, id, users ids and vehicle id. And a table B that contains vehicleid, and vehicle name.
Table A
---------------------------
| Id | User_id |Vehicle_id|
---------------------------
| 1 | 1 | 2 |
| 2 | 1 | 3 |
| 3 | 1 | 4 |
| 4 | 2 | 2 |
| 5 | 2 | 3 |
| 6 | 4 | 5 |
---------------------------
Table B
-------------------
| Id |Vehicle_name|
-------------------
| 1 | Car |
| 2 | Bike |
| 3 | Plane |
| 4 | Boat |
| 5 | Rocket |
-------------------
Given a user id, I need to get all vehicle names, that doesn't match with table A. I've tried Outer joins, but I can't manage to do get the info that i need.
For example: Given user id 1, the query should return Car and Rocket.
thanks in advance
This is simple enough using not in or not exists:
select b.*
from b
where not exists (select 1
from a
where a.vehicle_id = b.id and a.user_id = #a_user_id
);
I also thought of using a cross join and was able to get the output in case you are more comfortable with join logic.
SELECT CJOIN.USER_ID, CJOIN.VEHICLE_ID, CJOIN.VEHICLE_NAME
FROM
(SELECT DISTINCT A.USER_ID, B.ID AS VEHICLE_ID, B.VEHICLE_NAME FROM TABLE_A A CROSS JOIN TABLE_B B) CJOIN
LEFT JOIN
TABLE_A D
ON CJOIN.USER_ID = D.USER_ID AND CJOIN.VEHICLE_ID = D.VEHICLE_ID
WHERE D.USER_ID IS NULL AND D.VEHICLE_ID IS NULL;
First, I got all possible combinations of USER_ID x VEHICLE_ID by a cross join and used this table in a left join to pull records for which there is no match.
Related
I'm in front of a "minor" problem taht looks easy but I didn't suceed to resolve it.
I have three tables in my Database :
Table gp
____________
id | name |
____________
1 | Le Mans|
2 | Toulon |
3 | Rennes |
Table player
____________
id | name |
____________
1 | Thibaut|
2 | Fred |
3 | Samir |
Table Records
_____________________________
id | gp_id | player_id | time
_____________________________
1 | 1 | 1 | 17860
2 | 2 | 1 | 11311
3 | 3 | 1 | 33133
4 | 3 | 2 | 11113
5 | 2 | 2 | 44444
6 | 1 | 2 | 13131
7 | 1 | 3 | 11111
8 | 3 | 3 | 21112
I want to get a sum of time for players that have a record on every gp ( so in my case, just players Thibaut and Fred have a record on the 3 gp ( Samir has just a record on two gp ) ).
I have no idea how I can get that, of course this SQL query is retrieving a sum but from this query I want to escape the guys that don't have a record on every GPs, but I'm blocked at that point ...
SELECT p.name, sum(time)
from records r
join gp g on r.gp_id = g.id
join player p on r.player_id = p.id
group by r.player_id
Thanks in advance guys !
You could use having count to exclude the records that don't have a record on every GPs.
Try:
select p.name,
sum(`time`) as tot_sum
from records r
inner join player p on r.player_id=p.id
inner join gp g on g.id=r.gp_id
group by p.name
having count(distinct gp_id) = (select count(distinct id) from gp)
https://dbfiddle.uk/t8QwSFDY
having count(distinct gp_id) = (select count(distinct id) from gp) will match only the records in the record table that have a record on every gp.
I have 3 tables. clients, sales and potential_sales.
The basic structure is as follows:
Clients Table:
+-----------+-------+----------------+
| client_id | name | address |
+-----------+-------+----------------+
| 1 | john | 12 blue ave |
| 2 | paul | 34 green lane |
| 3 | peter | 69 yellow road |
+-----------+-------+----------------+
Potential Sales Table:
+----------+------------+---------------------+
|product_id | client_id | received_free_promo |
+-----------+------------+---------------------+
| 3 | 1 | 1 |
| 4 | 2 | 0 |
| 5 | 2 | 1 |
+-----------+------------+---------------------+
Sales:
+----------+-----------+-----------+
| sales_id | client_id | product_id |
+----------+-----------+------------+
| 1 | 2 | 4 |
| 2 | 43 | 4 |
| 3 | 2 | 5 |
| 4 | 18 | 93 |
+----------+-----------+------------+
I want to join clients and potential_sales tables ONLY IF
1) received_promo equals 1 AND
2) they actually bought the promo package (i.e. the product_id for the potential sale has an entry into the sales table ). If they didn't eventually buy the free_promo product then I do not want to join the clients and potential_sales table at all. This is important - I can't simply JOIN to figure it out because this is only a small part of a bigger query and I can't afford to JOIN for no reason.
(Here is how I would like it to work. It's mainly pseudo-code to describe what I want to happen)
SELECT
c.*
FROM
clients c
LEFT JOIN potential_sales ps ON ps.client_id=c.id
LEFT JOIN sales ps ON s.product_id=ps.product_id
IF(s.sales_id) JOIN potential_sales ps ON ps.client_id=c.id
How do I do this in MySQL? I haven't come close to a solution. Please help!
Try this:
SELECT A.*, B.product_id, B.received_free_promo
FROM Clients A JOIN
(SELECT * FROM PotentialSales
WHERE received_free_promo=1) B
ON A.client_id=B.client_id
WHERE EXISTS (SELECT 1 FROM Sales C
WHERE A.client_id=C.client_id
AND B.product_id=C.product_id);
See Demo on SQL Fiddle.
What you are missing is the EXISTS clause:
SELECT
C.*,
P.*
FROM
Clients AS C
INNER JOIN PotentialSales AS P ON C.client_id = P.client_id
WHERE
P.received_free_promo = 1 AND
EXISTS (
SELECT
'the client already sold that product'
FROM
Sales AS S
WHERE
S.client_id = C.client_id AND
S.product_id = P.product_id)
Try this..." select * from client as c natural join potential as p join sales as s on p.product_id = s.product_id where received_promo = 1". select * will mention everything from all the 3 tables. You can choose what you want as the result.
I have three tables
Table a
+-----+-------+
| aid | value |
+-----+-------+
| 1 | A |
| 2 | B |
| 3 | C |
| 4 | D |
+-----+-------+
Table b
+-----+------+
| bid | name |
+-----+------+
| 1 | A |
| 2 | B |
| 3 | C |
+-----+------+
Table ba (mapping of table a and table b)
+-----+-----+
| bid | aid |
+-----+-----+
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 3 | 2 |
| 1 | 3 |
| 2 | 3 |
| 2 | 4 |
+-----+-----+
From these tables I want a query like
SELECT aid, mapped('true'-if(aid exist in ba) 'false'-otherwise)
FROM a
JOIN b
JOIN ba
WHERE bid=1
to get a result from where I can generate a list
(when bid=1)
A-mapped
B-not mapped
C-mapped
D-not mapped
(when bid=2)
A-mapped
B-not mapped
C-mapped
D-mapped
(when bid=3)
A-mapped
B-mapped
C-not mapped
D-not mapped
Right now I am generating the list in a while loop for all the rows of table 'a' and inside the loop a query is executed for each iteration to check the existence in table 'ba'.
I think this is supposed to be table b independent:
SELECT CONCAT_WS('-', a.value, IF(ba.aid IS NULL, "-not mapped", "-mapped"))
FROM a LEFT JOIN ba ON a.aid = ba.aid AND ba.bid = 1
ORDER BY a.aid
Note: I took "a" table as the base table since your samples included all values from "a" table.
This is a tricky question, but the difficult part is in figuring out how to formulate the query. Once that is out of the way, it is downhill from there. One approach is to use a cross join between the A and B tables to obtain all possible mappings. Then LEFT JOIN to the mapping table to determine which pairs are being mapped and which are not. Try the following query:
SELECT tb.bid, ta.value,
CASE WHEN ba.bid IS NOT NULL THEN 'mapped' ELSE 'not mapped' END AS label
FROM tb INNER JOIN ta -- cross join to obtain all bid/aid pairs
LEFT JOIN ba -- to determine which pairs are mapped/not mapped
ON ta.aid = ba.aid AND tb.bid = ba.bid
ORDER BY tb.bid, ta.value
Demo here:
SQLFiddle
Say I have a database that has people, grocery stores, and items you can buy in the store, like so:
Stores People Foods
----------------- ------------------ ------------------
| id | name | | id | name | | id | name |
----------------- ------------------ ------------------
| 1 | Giant | | 1 | Jon Skeet | | 1 | Tomatoes |
| 2 | Vons | | 2 | KLee1 | | 2 | Apples |
| 3 | Safeway | ------------------ | 3 | Potatoes |
----------------- ------------------
I have an additional table which keep track of which stores sell what:
Inventory
--------------------
| store_id| food_id|
--------------------
| 1 | 1 |
| 1 | 2 |
| 2 | 1 |
| 3 | 1 |
| 3 | 2 |
| 3 | 3 |
--------------------
And I have another table that has shopping lists on it
Lists
---------------------
| person_id| food_id|
---------------------
| 1 | 1 |
| 1 | 2 |
| 1 | 3 |
| 2 | 1 |
| 2 | 3 |
---------------------
My question is, given a person, or their id, what is the best way to figure out what stores they can go to so they will get everything on their list. Is there a pattern for these types of computations in MySQL?
My attempt (very ugly and messy) is something like:
-- Given that _pid is the person_id we want to get the list of stores for.
SELECT stores.name, store_id, num, COUNT(*) AS counter
FROM lists
INNER JOIN inventory
ON (lists.food_id=inventory.food_id)
INNER JOIN (SELECT COUNT(*) AS num
FROM lists WHERE person_id=_pid
GROUP BY person_id) AS T
INNER JOIN stores ON (stores.id=store_id)
WHERE person_id=_pid
GROUP BY store_id
HAVING counter >= num;
Thanks for your time!
Edit SQL Fiddle with Data
If I were to solved the problem, I'll join the four tables with their linking column (specifically the foreign keys) then a subquery on the HAVING clause to count the number of items on the list for each person. Give this a try,
SET #personID := 1;
SELECT c.name
FROM Inventory a
INNER JOIN Foods b
ON a.food_id = b.id
INNER JOIN Stores c
ON a.store_id = c.id
INNER JOIN Lists d
ON d.food_id = b.id
WHERE d.person_id = #personID
GROUP BY c.name
HAVING COUNT(DISTINCT d.food_id) =
(
SELECT COUNT(*)
FROM Lists
WHERE person_ID = #personID
)
SQLFiddle Demo
#JohnWoo: why DISTINCT?
Another one...
SET #pid=2;
SELECT store_id, name
FROM inventory
JOIN lists ON inventory.food_id=lists.food_id
JOIN stores ON store_id=stores.id
WHERE person_id=#pid
GROUP BY store_id
HAVING COUNT(*)=(
SELECT COUNT(*)
FROM lists
WHERE person_id=#pid
);
Here is a simplified version of the pertinent part of my DB:
Person:
id
PersonSkills:
person_id
skillname
ability
Position:
id
PositionSkills:
position_id
skillname
ability
A person can have any number of PersonSkills, let's say in this instance, our user has 6.
A Position can require any number of PositionSkills, let's say in this instance the position requires 3.
I need a query that will determine whether ALL of the PositionSkills associated with this Position are present in the PersonSkills associated with this person. (I also need to ensure that the PersonSkill's ability is greater than the PositionSkill's ability, but I think that will be simple once I figure out the part that is giving me trouble here.)
Thanks in advance,
Jason
EDIT
Here is more detail on what I'm looking for:
PersonSkills
+-------------+---------+---------+
| person_id | skill | ability |
+-------------+---------+---------+
| 1 | A | 5 |
| 1 | B | 4 |
| 1 | C | 5 |
| 1 | D | 4 |
| 1 | E | 5 |
+-------------+---------+---------+
PositionSkills
+-------------+---------+---------+
| position_id | skill | ability |
+-------------+---------+---------+
| 5 | A | 3 |
| 5 | B | 3 |
| 5 | C | 3 |
| 6 | A | 3 |
| 6 | B | 3 |
| 6 | Z | 3 |
+-------------+---------+---------+
From the fact that I'm user 1, I want a query to tell me that I am qualified for Position 5, because I have skills A, B, and C, that it requires, but that I am not qualified for Position 6, because I lack skill Z
Thanks again,
Jason
Try this solution:
SELECT
a.id,
(COUNT(c.position_id) = (SELECT COUNT(*) FROM positionskills WHERE position_id = <position_id here>)) AS isQualified
FROM
person a
LEFT JOIN
personskills b ON a.id = b.person_id
LEFT JOIN
positionskills c ON
b.skillname = c.skillname AND
b.ability >= c.ability AND
c.position_id = <position_id here>
GROUP BY
a.id
WHERE
a.id = <person_id here>
If the person is qualified, isQualified will be 1 else it will be 0
EDIT: As per clarification in the question, to get all the positions for which the person is qualified for, use this solution:
SELECT
a.position_id
FROM
(
SELECT bb.position_id, COUNT(*) AS skillshave
FROM personskills aa
INNER JOIN positionskills bb ON aa.skillname = bb.skillname AND aa.ability >= bb.ability
WHERE aa.person_id = <person_id here>
GROUP BY bb.position_id
) a
INNER JOIN
(
SELECT position_id, COUNT(*) AS skillsrequired
FROM positionskills
GROUP BY position_id
) b ON a.position_id = b.position_id AND a.skillshave = b.skillsrequired