MySQL - Query to select data from 3 different tables using joins - mysql

I have 3 tables in my MySQL DB (contract, contract_details, contract_receiving). The table structures are given below:
Contract
c_id | c_date | c_vendor | c_ref
---------+------------+------------+--------
1 | 2/27/2020 | MS Traders | n/a
2 | 2/28/2020 | MS Traders | n/a
3 | 2/29/2020 | J Premiers | n/a
Contract_Details
cc_id | cd_contract_id | cd_item | cd_qty | cd_rate | cd_total
---------+----------------+---------------+--------+---------+---------
1 | 1 | HP Laptop | 3 | 5300 | 15900
2 | 1 | Dell Laptop | 5 | 5700 | 28500
3 | 2 | HP Printer | 8 | 2500 | 20000
4 | 3 | Epson Printer | 5 | 3500 | 17500
5 | 3 | IB Scanner | 5 | 4200 | 21000
Contract_Receiving
cr_id | cr_cd_id | cr_date | cr_qty
---------+-----------+-------------+---------
1 | 1 | 3/1/2020 | 3
2 | 2 | 3/1/2020 | 5
3 | 3 | 3/3/2020 | 2
4 | 3 | 3/8/2020 | 2
I want to get the following result from three tables:
c_id | c_vendor | items_received | items_total
-------+------------+----------------+-------------
1 | MS Traders | 8 | 8
2 | MS Traders | 4 | 8
3 | J Premiers | 0 | 10
I am using the following query but not getting the desired result. Please guide me to write the query to get the desired result. Thanks
SELECT contract.*, IFNULL(SUM(cr_qty),0) AS 'Received', SUM(contract_detail.cd_qty) AS 'Total'
FROM `contract_receiving`
LEFT JOIN contract_detail ON (contract_receiving.cr_cd_id = contract_detail.cd_id)
LEFT JOIN contract ON (contract.c_id = contract_detail.cd_contract_id)
GROUP BY contract.c_id

You can get your expected result by calcurating items_received and items_total before joining.
SELECT
c.c_id,
c.c_vendor,
COALESCE(cr.items_received, 0) items_received,
COALESCE(cd.items_total, 0) items_total
FROM contract c
LEFT JOIN
( SELECT cd_contract_id, SUM(cd_qty) items_total
FROM contract_detail
GROUP BY cd_contract_id) cd
ON c.c_id=cd.cd_contract_id
LEFT JOIN
( SELECT cd_contract_id, SUM(cr_qty) items_received
FROM contract_receiving
INNER JOIN contract_detail
ON cd_id=cr_cd_id
GROUP BY cd_contract_id) cr
ON c.c_id=cr.cd_contract_id
DB Fiddle

Related

How to subtract a value from a sum of total in MySql LEFT JOIN Query

I have 2 tables.
SELECT * FROM purchases;
+------+---------+-----------+
|purid | total_q | dstatus |
+------+---------+-----------+
| 1 | 45 | DELIVERED |
| 2 | 50 | LOADING |
| 3 | 24 | DELIVERED |
| 4 | 15 | DELIVERED |
| 5 | 10 | DELIVERED |
+------+---------------------+
SELECT * FROM warehouse;
+------+-------+---------+
| wid | purid | total_q |
+------+-------+---------+
| 4 | 1 | 45 |
| 5 | 4 | 15 |
| 9 | 3 | 10 |
| 12 | 3 | 5 |
+------+-------+---------+
I want to get "delivered" purchases with its amounts which are not already included in warehouse table. Here is the demo where I stuck: DEMO
The query which I use is:
SELECT p.purid as purid, (p.total_q - IFNULL(w.total_q,0)) as ntq
FROM `purchases` as p
LEFT JOIN `warehouse` as w ON p.purid=w.purid
WHERE p.dstatus = "DELIVERED" AND (p.total_q - IFNULL(w.total_q,0)) > 0
My desired output:
+-------+------+
| purid | ntq |
+-------+------+
| 5 | 10 |
| 3 | 9 |
+------+-------+
The problem is I could not subtract "total_q (24) from purchases table" from "sum total_q(10+5) from warehouse table".
You can try to use subquery aggregate warehouse by purid before join otherwise you might get multiple rows.
Query #1
SELECT p.purid as purid,
p.total_q - IFNULL(w.total_q,0) as ntq
FROM `purchases` as p
LEFT JOIN (
SELECT purid,SUM(total_q) total_q
FROM warehouse
GROUP BY purid
) as w ON p.purid=w.purid
WHERE p.dstatus = "DELIVERED"
AND p.total_q - IFNULL(w.total_q,0) > 0;
purid
ntq
3
9
5
10
View on DB Fiddle

Mysql returning incorrect COUNT when using more than one JOIN?

I have 3 tables: NAMES, REGISTRATIONS, and RENEWALS. I'm using LEFT JOIN to join the 3 tables with a common ID.
I need to count the number of REGISTRATIONS of each user, as well as the number of RENEWALS. I've tried using different options in the GROUP BY field, but none seemed to work.
Here's the SELECT statement:
SELECT
names.name_id AS 'Names ID'
,names.name AS Name
,count(registrations.date) AS Registrations
,count(renewals.date) AS Renewals
FROM names
LEFT JOIN registrations
ON names.name_id = registrations.name_id
LEFT JOIN renewals
ON renewals.name_id = registrations.name_id
GROUP BY names.name_id, registrations.name_id, renewals.name_id;
And here are the 3 tables:
TABLE: names
+---------+------+
| name_id | name |
+---------+------+
| 1 | Ana |
| 2 | John |
| 3 | Paul |
+---------+------+
TABLE: registrations
+-----------------+---------+---------------------+-------+
| registration_id | name_id | date | value |
+-----------------+---------+---------------------+-------+
| 1 | 1 | 2014-01-30 13:15:02 | 15 |
| 2 | 2 | 2014-05-01 18:01:44 | 15 |
| 3 | 2 | 2014-07-08 15:10:43 | 20 |
| 4 | 3 | 2012-09-28 17:45:32 | 15 |
| 5 | 3 | 2014-01-09 18:26:14 | 20 |
| 6 | 3 | 2015-01-10 13:22:01 | 25 |
+-----------------+---------+---------------------+-------+
TABLE: renewals
+------------+---------+---------------------+-------+
| renewal_id | name_id | date | value |
+------------+---------+---------------------+-------+
| 1 | 1 | 2015-01-30 00:00:00 | 5 |
| 2 | 1 | 2016-02-12 00:00:00 | 5 |
| 3 | 1 | 2015-06-01 00:00:00 | 5 |
| 4 | 1 | 2013-11-24 00:00:00 | 5 |
| 5 | 2 | 2015-01-27 00:00:00 | 5 |
+------------+---------+---------------------+-------+
Here's the INCORRECT result I'm getting:
+----------+------+---------------+----------+
| Names ID | Name | Registrations | Renewals |
+----------+------+---------------+----------+
| 1 | Ana | 4 | 4 |
| 2 | John | 2 | 2 |
| 3 | Paul | 3 | 0 |
+----------+------+---------------+----------+
The CORRECT result I was expecting would be:
+----------+------+---------------+----------+
| Names ID | Name | Registrations | Renewals |
+----------+------+---------------+----------+
| 1 | Ana | 1 | 4 |
| 2 | John | 2 | 1 |
| 3 | Paul | 3 | 0 |
+----------+------+---------------+----------+
How can I fix the query to get a correct result?
Try this:
SELECT
names.name_id AS 'Names ID'
,names.name AS Name
,count(distinct registrations.registration_id) AS Registrations
,count(distinct renewals.renewal_id) AS Renewals
FROM names
LEFT JOIN registrations
ON names.name_id = registrations.name_id
LEFT JOIN renewals
ON renewals.name_id = registrations.name_id
GROUP BY names.name_id, registrations.name_id, renewals.name_id;
Whenever I run into this type of issue, I find it helps to just run a select * query if your server can take it. Like this:
SELECT *
FROM names
LEFT JOIN registrations
ON names.name_id = registrations.name_id
LEFT JOIN renewals
ON renewals.name_id = registrations.name_id ;
That will let you see what you are really counting.
Your query is executed just fine.
After the first join you have 1 entry for Ana, 2 entries for John and 3 for Paul.
After the seconds join the one entry for Ana is duplicated 4 times and joined (concatenated) with the 4 renewals. If you now count the registration dates for Ana you get 4. That is where your "errors" come from.
You could for example count the distinct dates to fix it.

MySql query to perform join between 2 tables

These are the tables:
professor
+-------+--------+--------+--------+------+
| empid | name | status | salary | age |
+-------+--------+--------+--------+------+
| 1 | Arun | 1 | 2000 | 23 |
| 2 | Benoy | 0 | 3000 | 25 |
| 3 | Chacko | 1 | 1000 | 36 |
| 4 | Divin | 0 | 5000 | 32 |
| 5 | Edwin | 1 | 2500 | 55 |
| 7 | George | 0 | 1500 | 46 |
+-------+--------+--------+--------+------+
works
+----------+-------+---------+
| courseid | empid | classid |
+----------+-------+---------+
| 1 | 1 | 10 |
| 2 | 2 | 9 |
| 3 | 3 | 8 |
| 4 | 4 | 10 |
| 5 | 5 | 9 |
| 6 | 1 | 9 |
+----------+-------+---------+
The above are the tables from which I need to retrieve the data from.
The question is to return list of Employees who take both Class 10 and
Class 9.
The query I have written is:
select professor.name
from inner join works
on professor.empid=works.empid
where works.classid=9 and works.classid=10;
I know that the result I want is Arun, but I don't know what should be the exact query to retrieve the required result.
He wants the professeors that take class 9 AND 10. So there are 2 different records in works that need to match.
select professor.name from professor
join works A on A.empid=professor.empid and A.classid=9
join works B on B.empid=professor.empid and B.classid=10
See http://sqlfiddle.com/#!2/4be88a/1
Try This
select professor.name
from professor inner join works
on professor.empid=works.empid
where works.classid=9 OR works.classid=10;
(OR)
select professor.name
from professor inner join works
on professor.empid=works.empid
where works.classid IN ('9','10')
SELECT prof.name FROM professor AS prof
JOIN works
ON prof.empid = works.empid
WHERE works.classid IN (9, 10);

How should I write this MySQL query containing multiple Left Joins

I have a query consisting of multiple joins and I am wondering whether it can be re-written to improve performance.
I have 2 tables as follows (I have removed non-important columns for this example):
slots
------------------------------------------
| id | name | slot_1 | slot_2 | slot_3 |
------------------------------------------
| 1 | Bob | 1 | 2 | 3 |
| 2 | Jim | 4 | 3 | 3 |
| 3 | Alf | 1 | 2 | 5 |
------------------------------------------
(There are 25 slots in total, each in it's own column)
slot_details
-----------------------------------
| id | stat_1 | stat_2 | stat_3 |
-----------------------------------
| 1 | 1 | 5 | 6 |
| 2 | 4 | 31 | 23 |
| 3 | 6 | 5 | 7 |
| 4 | 7 | 4 | 9 |
| 5 | 2 | 3 | 5 |
-----------------------------------
(There are 10 stats in total)
The query is as follows:
SELECT
slots.name,
slot_1_details.stat_1 AS slot_1_stat_1,
slot_1_details.stat_2 AS slot_1_stat_2,
slot_1_details.stat_3 AS slot_1_stat_3,
slot_2_details.stat_1 AS slot_2_stat_1,
slot_2_details.stat_2 AS slot_2_stat_2,
slot_2_details.stat_3 AS slot_2_stat_3,
slot_3_details.stat_1 AS slot_3_stat_1,
slot_3_details.stat_2 AS slot_3_stat_2,
slot_3_details.stat_3 AS slot_3_stat_3
FROM
slots
LEFT JOIN
slot_details AS slot_1_details
ON (
slot_1_details.id = slots.slot_1
)
LEFT JOIN
slot_details AS slot_2_details
ON (
slot_2_details.id = slots.slot_2
)
LEFT JOIN
slot_details AS slot_3_details
ON (
slot_3_details.id = slots.slot_3
)
WHERE (
slots.id = 1
)
The expected outcome of this query would be as follows:
| name | slot_1_stat_1 | slot_1_stat_2 | slot_1_stat_3 | slot_2_stat_1 | slot_2_stat_2 | slot_2_stat_3 | slot_3_stat_1 | slot_3_stat_2 | slot_3_stat_3 |
|bob | 1 | 5 | 6 | 4 | 31 | 23 | 6 | 5 | 7 |
Unfortunately I am not in a situation where I can change the tables.
Thank you for the help!
maybe
SELECT * FROM slots s LEFT JOIN slot_details sd ON s.id=sd.id
but i'm not sure because the query you posted is very confusing.
what are the keys of those tables?

Complex 3 way SQL join (where table 3 has to join table 2 before joining table 1)

I have three existing SQL tables we will call "teams", "miles", and "riders". Leaving out the fluff, their structure looks like this:
Table: teams
------------+-------------+---------+
| team_name | captains_id | team_id |
------------+-------------+---------+
| superbads | 11 | 1 |
| superflys | 12 | 2 |
------------+-------------+---------+
Table: riders
--------------+-----------+----------+
| rider_name | team_id | rider_id |
--------------+-----------+----------+
| donatello | 1 | 10 |
| leonardo | 1 | 11 |
| michelangelo| 2 | 12 |
| raphael | 2 | 13 |
--------------+-----------+----------+
Table: miles
--------------+-----------+----------+
| rider_id | miles | id |
--------------+-----------+----------+
| 10 | 100 | 1 |
| 10 | 62 | 2 |
| 11 | 110 | 3 |
| 11 | 100 | 4 |
| 12 | 8 | 5 |
| 12 | 22 | 6 |
| 13 | 29 | 7 |
| 13 | 2 | 8 |
--------------+-----------+----------+
I need to return a list of teams with total miles generated by that team (I also need to return the team captain's name, but that's a bit easier).
The difficulty is that I need to join miles on riders, sum the "miles" field, and then join that on teams somehow.
Changing the table structure is pretty much out, as this is an existing application. This is a LAMP environment, so manipulating PHP arrays after the query is an option if needed.
This should do it:
select t.team_id, t.team_name, t.captains_id, sum(m.miles) as total_miles
from teams t
inner join riders r on r.team_id = t.team_id
inner join miles m on m.rider_id = r.rider_id
group by t.team_id, t.team_name, t.captains_id