I have the following tables:
Teams
+------+--------------+--------------+
| id | team_name | team_code |
+------+--------------+--------------+
| 1 | Wales | WAL |
| 2 | England | ENG |
| 3 | New Zealand | NZL |
+------+--------------+--------------+
Matches
+------+-----------+-----------+
| id | team_a | team_b |
+------+-----------+-----------+
| 1 | WAL | ENG |
| 2 | ENG | NZL |
| 3 | WAL | NZL |
+------+-----------+-----------+
I know how a join works, but I can't get my head around how I can query to the database by Matched.id to get the team name for BOTH teams from the Teams database. Let me explain better
For each match I need to determine the team names
I will query by Matches.id
So for Match: 1 I'll need to select 'Wales' and 'England'
Hope I've explained my problem clearly enough, but If I haven't please feel free to ask more questions
The database structure seems to be "off" to me.
You should have both team_a and team_b as foreign keys to the Teams table primary key.
You can then join on the IDs (twice) to get the full names.
Matches:
+------+-----------+-----------+
| id | team_a | team_b |
+------+-----------+-----------+
| 1 | 1 | 2 |
| 2 | 2 | 3 |
| 3 | 1 | 3 |
+------+-----------+-----------+
SELECT T1.team_name, T2.team_name
FROM Matches M
INNER JOIN Teams T1
ON M.team_a = T1.id
INNER JOIN Teams T2
ON M.team_b = T2.id
WHERE M.id = 1
Select
matches.*,
teamA.team_name as TeamA_Name,
teamB.team_name as TeamB_Name
from matches
inner join teams teamA on matches.team_a = TeamA.team_code
inner join teams teamB on matches.team_b = TeamB.team_code
where
matches.id = 1
select
m.id,
t1.team_name,
t2.team_name
from
Matches m
inner join Teams t1 on m.team_a = t1.team_code
inner join Teams t2 on m.team_b = t2.team_code
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 three tables (form_completions, customer_sessions and conversion_sessions) which are design like the below, these are heavily striped down for the purpose of this example:
Form_completions:
id | name | email
------------------------
101 | Tom | tom#website.com
102 | Ben | ben#website.com
Customer_sessions:
id | customer_id | session_id | session_source
---------------------------------
1 | 900 | 9kc73bsf | twitter
2 | 901 | 15jvuw83 | google
3 | 901 | 45h73bgf | twitter
Conversion_sessions:
id | customer_id | session_id | form_completion_id
------------------------------------
1 | 900 | 9kc73bsf | 101
2 | 901 | 45h73bgf | 102
The query that i currently have is:
SELECT custsess.session_source,
c.id as form_conversion_id,
c.name,
FROM conversion_sessions convsess
LEFT JOIN form_completions fc
ON convsess.`form_completion_id` = fc.`id`
LEFT JOIN customer_sessions custsess
ON custsess.`customer_id` = convsess.`customer_id`
This will give me the following:
session_source | form_conversion_id | name
------------------------------------------
twitter | 101 | Tom
google | 102 | Ben
twitter | 102 | Ben
But what i need is to avoid the duplication of form_conversion_id and only include the most recent so it would be...
session_source | form_conversion_id | name
------------------------------------------
twitter | 101 | Tom
twitter | 102 | Ben
Hopefully this makes sense.
Solution to your problem:
SELECT custsess.session_source,
fc.id as form_conversion_id,
fc.name
FROM conversion_sessions AS convsess
INNER JOIN form_completions AS fc
ON convsess.form_completion_id = fc.id
INNER JOIN customer_sessions AS custsess
ON custsess.customer_id = convsess.customer_id
AND custsess.session_id = convsess.session_id
While joining you forgot to join customer_sessions and coversion_sessions ON session_id.
OUTPUT:
session_source form_conversion_id name
twitter 01 Tom
twitter 102 Ben
For demo follow the below link:
https://www.db-fiddle.com/f/pQG4VCWAnoGtRJa6MkvST6/0
You need a Subquery to get the most recent, change your JOIN to something like this
LEFT JOIN customer_sessions custsess
ON custsess.id =
(
SELECT MAX(id)
FROM Customer_sessions
WHERE c.id = custsess.customer_id
)
Looking to your data You should just use inner join
You should use inner join on a subquery for max session_id
SELECT custsess.session_source,
c.id as form_conversion_id,
c.name,
FROM conversion_sessions convsess
customer_sessions custsess ON custsess.`customer_id` = convsess.`customer_id`
INNER JOIN (
select customer_id, max(session_id) as max_sess
from Customer_sessions
group by customer_id
) t on t.customer_id = custsess.customer_id and t.max_sess = custsess.session_id
INNER JOIN form_completions fc ON convsess.`form_completion_id` = fc.`id`
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.
A customer can make many inquiries, and an inquiry can have many updates. I'm trying to view each inquiry and the latest update. I'm able to pull the latest date but not the update that's relevant to it. I've seen answers similar to mine but they only seem to deal with one join and I don't understand how I can use those to find a solution.
Here's my sql
select c.name, i.inquirycontent, u.updatecontent, max(u.date) from inquiries i
inner join customers c on c.customerid = i.customerid
left join updates u on u.inquiryid = i.inquiryid
group by i.inquiryid
Even if I omit the customer table, I am still unable to match the latest update to its content. How can I do this?
edit - as requested, here is some sample data
+------------+------+
| customerid | name |
+------------+------+
| 1 | jeff |
+------------+------+
| 2 | anne |
+------------+------+
+-----------+-----------------+------------+
| inquiryid | inquirycontent | customerid |
+-----------+-----------------+------------+
| 1 | inquiry1content | 1 |
+-----------+-----------------+------------+
| 2 | inquiry2content | 1 |
+-----------+-----------------+------------+
| 3 | inquiry3content | 2 |
+-----------+-----------------+------------+
+----------+-----------------+-----------+----------+
| updateid | updatecontent | inquiryid | date |
+----------+-----------------+-----------+----------+
| 1 | update1content | 1 | 01-01-17 |
+----------+-----------------+-----------+----------+
| 2 | update2content | 1 | 03-01-17 |
+----------+-----------------+-----------+----------+
| 3 | update3content | 3 | 04-01-17 |
+----------+-----------------+-----------+----------+
And here's what I want the query to output -
+------+-----------------+----------------+----------+
| name | inquirycontent | latestupdate | date |
+------+-----------------+----------------+----------+
| jeff | inquiry1content | update2content | 03-01-17 |
+------+-----------------+----------------+----------+
| jeff | inquiry2content | NULL | NULL |
+------+-----------------+----------------+----------+
| anne | inquiry3content | update3content | 04-01-17 |
+------+-----------------+----------------+----------+
This is a crude solution using UNION, but it works for what I need. The first select finds all unique inquiries by their latest update, and the second select finds all rows that haven't yet been updated.
(select c.name, i.inquirycontent, u.updatecontent, t2.mxdate
from updates u
inner join inquiries i on i.inquiryid = u.inquiryid
inner join customers c on c.customerid = i.customerid
inner join
(
select max(u.date) mxdate, i.inquiryid
from updates u
left join inquiries i on i.inquiryid = u.inquiryid
group by i.inquiryid
) t2
on u.inquiryid = t2.inquiryid
and u.date = t2.mxdate)
UNION
(select c.name, i.inquirycontent, u.updatecontent, u.date
from inquiries i
left join updates u on u.inquiryid = i.inquiryid
inner join customers c on c.customerid = i.customerid
where u.updatecontent is NULL)
I have this database structure:
sites
id | name
1 | Site 1
2 | Site 2
locations
id | city
23 | Baltimore
24 | Annapolis
people
id | name
45 | John
46 | Sue
sites_meta
id | site_id | meta_name | meta_value
1 | 1 | local | 23
2 | 1 | person | 45
3 | 2 | local | 24
4 | 2 | person | 46
So, as you can see, Site 1 (id 1) is in Baltimore and is associated with John, Site 2 (id 2) is in Annapolis and associated with Sue.
I need to figure out a clever sql statement that can return
id | name | id | city | id | name
1 | Site 1 | 23 | Baltimore | 45 | John
2 | Site 2 | 24 | Annapolis | 46 | Sue
I would be super appreciative if anyone can help me out. I've tried a few combinations of a select statement, but I keep getting stuck with using two values from the sites_meta table.
select
s.id as siteId,
s.name as siteName,
max(l.id) as locationId,
max(l.city) as city,
max(p.id) as personId,
max(p.name) as personName
from
sites_meta sm
join sites s on s.id = sm.site_id
left join locations l on l.id = sm.meta_value and sm.meta_name = 'local'
left join people p on p.id = sm.meta_value and sm.meta_name = 'person'
group by
s.id,
s.name
You can probably imagine how this kind of "meta" table might become a pain... especially as more items are added to it.
Instead, you might consider replacing it with two new tables, sites_locations and sites_people.
SELECT
s.id,s.name,l.id,l.city,p.id,p.name
FROM
sites s
INNER JOIN sites_meta sm1 ON s.id = sm1.site_id
INNER JOIN sites_meta sm2 ON s.id = sm2.site_id
INNER JOIN locations l ON sm1.meta_value = l.id AND sm1.meta_name = 'local'
INNER JOIN people p ON sm2.meta_value = p.id AND sm2.meta_name = 'person'
;