Given the database schema:
Part( PID, PName, Producer, Year, Price)
Customer( CID, CName, Province)
Supply(SID, PID, CID, Quantity, Amount, Date)
And the query:
Select cname, Province
From Customer c
Where exists (
Select *
from Supply s
join Part p on p.pId = s.pId
Where CId = c.CId
and p.Producer = 'Apple'
)
and Not exists (
Select *
from Supply n
join Part nap on nap.pId = n.pId
Where CId = c.CId
and nap.Producer != 'Apple'
)
How would I go about rewriting this query without the two sub queries?
You can use the LEFT JOIN/NULL pattern to find customers who haven't bought any non-Apple products. Then you can do this all with just joins. You'll have to join with Supply and Parts twice, once for finding Apple products, then again for excluding non-Apple products.
SELECT distinct c.name, c.province
FROM Customer AS c
JOIN Supply AS s1 ON s1.cid = c.cid
JOIN Parts AS p1 ON p1.pid = s1.pid
LEFT JOIN Supply AS s2 ON s2.cid = c.cid
LEFT JOIN Parts AS p2 ON p2.pid = s2.pid AND p2.producer != 'Apple'
WHERE p1.producer = 'Apple' AND p2.pid IS NULL
Notice that in the LEFT JOIN you put restrictions of the second table in the ON clause, not the WHERE clause. See Return row only if value doesn't exist for more about this part of the query.
You want customer who only bought Apple products?
One possible solution is based on conditional aggregation:
Select c.cname, c.Province
From Customer c
join
( -- this is not a Subquery, it's a Derived Table
Select s.CId -- assuming there's a CId in Supply
from Supply s
join Part p
on p.pId = s.pId
group by s.CId
-- when there's any other supplier this will return 1
having max(case when p.Producer = 'Apple' then 0 else 1 end) = 0
) as p
on p.CId = c.CId
Related
This is a MySQL question. I have three tables with the following columns:
transactions (table): transact_id, customer_id, transact_amt, product_id,
products (table): product_id, product_cost, product_name, product_category
customers (table): customer_id, joined_at, last_login_at, state, name, email
I'd like a query that finds out the most popular item in every state and the state. One of the tricky parts is that some product_name have multiple product_id. Therefore I though joining the three tables that generate an output with two columns: state and product_name. Until here that worked fine doing this:
SELECT p.product_name, c.state
FROM products p
INNER JOIN transactions t
ON p.product_id = t.product_id
INNER JOIN customers c
ON c.customer_id = t.customer_id
This selects all the products, and the states from where the customer is. The problem is that I can't find the way to rank the mos popular product per state. I tried different group by, order by and using subqueries without success. I suspect I need to do subqueries, but I can't find the way to resolve it. The expected outcome should look like this:
most_popular_product | state
Bamboo | WA
Walnut | MO
Any help will be greatly appreciated.
Thank you!
You need a subquery that gets the count of transactions for each product in each state.
SELECT p.product_name, c.state, COUNT(*) AS count
FROM products p
INNER JOIN transactions t
ON p.product_id = t.product_id
INNER JOIN customers c
ON c.customer_id = t.customer_id
GROUP BY p.product_name, c.state
Then write another query that has this as a subquery, and gets the highest count for each state.
SELECT state, MAX(count) AS maxcount
FROM (
SELECT p.product_name, c.state, COUNT(*) AS count
FROM products p
INNER JOIN transactions t
ON p.product_id = t.product_id
INNER JOIN customers c
ON c.customer_id = t.customer_id
GROUP BY p.product_name, c.state
) AS t
GROUP BY state
Finally, join them together:
SELECT t1.product_name AS most_popular_product, t1.state
FROM (
SELECT p.product_name, c.state, COUNT(*) AS count
FROM products p
INNER JOIN transactions t
ON p.product_id = t.product_id
INNER JOIN customers c
ON c.customer_id = t.customer_id
GROUP BY p.product_name, c.state
) AS t1
JOIN (
SELECT state, MAX(count) AS maxcount
FROM (
SELECT p.product_name, c.state, COUNT(*) AS count
FROM products p
INNER JOIN transactions t
ON p.product_id = t.product_id
INNER JOIN customers c
ON c.customer_id = t.customer_id
GROUP BY p.product_name, c.state
) AS t
GROUP BY state
) AS t2 ON t1.state = t2.state AND t1.count = t2.maxcount
This is basically the same pattern as SQL select only rows with max value on a column, just using the first grouped query as the table you're trying to group.
I am trying to fetch the value of available stock in MYSQL but when the number of rows gets more than 35000 request is failing with no response. I use subqueries to fetch the value of the available stock.
Here is my code:
SELECT
p.`product-id` AS id,
p.`product-id` AS product_id,
ped.purchase_entry_id AS purchase_id,
p.`product-name` AS name,
m.name AS manufacturer,
p.`product-type` AS product_type,
ped.id AS batch_no,
ped.internal_sales_rate AS barcode,
c.name as category,
ped.size AS size,
IFNULL(ped.sales_rate,0) AS sales_rate,
IFNULL(ped.purchase_rate,0) AS purchase_rate,
IFNULL(SUM(ped.units),0) AS units_purchased,
(select IFNULL(SUM(sed.qty),0) FROM sales_entry_details sed WHERE (sed.batch_no = ped.id)) AS units_sold,
(select IFNULL(SUM(sr.qty),0) FROM sales_return_item sr WHERE (sr.batch_no = ped.id)) AS retured,
(select IFNULL(SUM(pri.qty),0) FROM purchase_return_items pri WHERE (pri.batch_no = ped.id)) AS purchase_return,
(select IFNULL(SUM(ast.qty),0) FROM adjustment_stock ast WHERE (ast.batch_no = ped.id)) AS adjustment,
(select IFNULL(SUM(ast2.batch_no),0) FROM adjustment_stock ast2 WHERE (ast2.batch_no = ped.id)) AS isChecked
FROM purchase_entry_details ped
LEFT JOIN products p on p.`product-id` = ped.product_id
LEFT JOIN category c ON c.id = p.`product-type`
LEFT JOIN manufacturer m ON m.id = p.manufacturer
GROUP BY ped.id;
Is there any better option to fetch the value of stock available in SQL??
The query looks fine. As there is no limiting criteria (no WHERE clause), you'll read the whole table sequentially.
You'd want indexes on batch_no in the involved tables of course. But I guess these are foreign keys to some batch table, so the indexes should already exist.
The only thing that I notice is that you select from adjustment_stock twice. You can avoid this by moving the subqueries to your FROM clause:
SELECT
p.`product-id` AS id,
p.`product-id` AS product_id,
ped.purchase_entry_id AS purchase_id,
p.`product-name` AS name,
m.name AS manufacturer,
p.`product-type` AS product_type,
ped.id AS batch_no,
ped.internal_sales_rate AS barcode,
c.name as category,
ped.size AS size,
IFNULL(ped.sales_rate,0) AS sales_rate,
IFNULL(ped.purchase_rate,0) AS purchase_rate,
IFNULL(SUM(ped.units),0) AS units_purchased,
IFNULL(sed.sum_qty),0) AS units_sold,
IFNULL(sr.sum_qty),0) AS retured,
IFNULL(pri.sum_qty),0) AS retured,
IFNULL(ast.sum_qty),0) AS adjustment,
IFNULL(ast.sum_batch_no),0) AS isChecked
FROM purchase_entry_details ped
LEFT JOIN products p on p.`product-id` = ped.product_id
LEFT JOIN category c ON c.id = p.`product-type`
LEFT JOIN manufacturer m ON m.id = p.manufacturer
LEFT JOIN
(
select batch_no, sum(qty) as sum_qty from sales_entry_details group by batch_no
) sed on sed.batch_no = ped.id
LEFT JOIN
(
select batch_no, sum(qty) as sum_qty from sales_return_item group by batch_no
) sr on sr.batch_no = ped.id
LEFT JOIN
(
select batch_no, sum(qty) as sum_qty from purchase_return_items group by batch_no
) pri on pri.batch_no = ped.id
LEFT JOIN
(
select batch_no, sum(qty) as sum_qty, sum(batch_no) as sum_batch_no
from adjustment_stock group by batch_no
) ast on ast.batch_no = ped.id
GROUP BY ped.id;
(Adding up batch numbers seems a bit weird, though.)
You can make separate joins for each table used in subqueries against purchase_entry_details table. In all these separate selects make group by ped.id. Afterwards make left join to new tables with sums.
SELECT
...
SED.sumqty,
SR.sumqty,
...
FROM purchase_entry_details ped
LEFT JOIN products p on p.`product-id` = ped.product_id
LEFT JOIN category c ON c.id = p.`product-type`
LEFT JOIN manufacturer m ON m.id = p.manufacturer
LEFT JOIN (
SELECT ped1.id, SUM(sed1.qty) as sumqty
FROM purchase_entry_details ped1
JOIN sales_entry_details sed1 ON sed1.batch_no = ped1.id
GROUP BY ped1.id
) SED ON SED.id = ped.id
LEFT JOIN (
SELECT ped1.id, SUM(sr1.qty) as sumqty
FROM purchase_entry_details ped1
JOIN sales_return_item sr1 ON sr1.batch_no = ped1.id
GROUP BY ped1.id
) SR ON SR.id = ped.id
...
Given database schema:
Part( P#, PName, Producer, Year, Price)
Customer( C#, CName, Province)
Supply(S#, P#, C#, Quantity, Amount, Date)
How would I create a query to list names and provinces of the customers who did not buy any Apple products?
I have:
SELECT
b.cname,
b.province
FROM
part c,
customer b,
supply a
WHERE
c.PID = a.PID
AND b.CID = a.CID
AND c.producer != 'Apple'
However this returns all customers who bought something other than an Apple product. So I need to be able to compare to other records.
here, the customers who have not purchased Apple products
Select cname, Province
From Customer c
Where not exists
(Select * from Supply s
join Part p on p.pId = s.pId
Where CId = c.CId
and p.Producer = 'Apple')
and here select the customers who have only purchased Apple products:
Select cname, Province
From Customer c
Where exists
(Select * from Supply s
join Part p on p.pId = s.pId
Where CId = c.CId
and p.Producer = 'Apple')
and Not exists -- <- filter out the customers without an Apple product
(Select * from Supply n
join Part nap on nap.pId = n.pId
Where CId = c.CId
and nap.Producer != 'Apple')
Given the schema:
Part( PID, PName, Producer, Year, Price)
Customer( CID, CName, Province)
Supply(SID, PID, CID, Quantity, Amount, Date)
And the query:
Select Cname, Province
From Customer c
Where not exists
(Select * from Supply s
join Part p on p.PID = s.PID
Where CID = c.CID
and p.Producer = 'Apple')
How would I go about rewriting this query without a subquery? I've looked at other posts and most mention using a join however I'm confused as to how to approach it.
Something like this should work:
Select distinct Cname, Province
From Customer c
left join Supply s on s.CID = c.CID
left join Part p on p.PID = s.PID and p.Producer = 'Apple'
where p.PID is null
You can use left join
SELECT Cname, Province
FROM Customer c
LEFT JOIN Supply s ON c.id = s.id
JOIN Part p on p.PID = s.PID
WHERE s.Producer = 'Apple'
AND s.id is NULL;
Try the following.
Select Cname, Province
From Customer c
-- join whatever the table that you have common customer id
left join Supply s s.cid = c.cid
join Part p on p.PID = s.PID and p.Producer = 'Apple'
where s.cid is null
I need to query for the users with highest amount of sales by all projects, where the users are in users table, sales in units table, projects in projects table.
Projects Top Agent Total Sales for Project
Project A User A 100000
Project B User B 20000
Project C User A 1000
Project D - 0
The Projects column is list all the projects regardless it has sales or not.
The Top Agent column is list the user with the highest sales in the project.
The Total Sales for Project is the total sales for a projects.
The agent column i got is incorrect because there is someone else has the highest sales, the query seems to return the first row of the result
SELECT projects, pid, CASE WHEN agent is null THEN '-' ELSE agent END as agent,
CASE WHEN FORMAT(topagent,0) > 0 THEN FORMAT(topagent,0) ELSE 0 END as salesvolume
FROM (
SELECT projects.name as projects, projects.id as pid,
concat(users.f_name, ' ', users.l_name) as agent,
SUM(units.price) AS topagent
FROM users inner join bookings on bookings.agent_id = users.id
inner join units on bookings.unit = units.id
inner join types on types.id = units.types_id
inner join projects on projects.id = types.project_id
WHERE units.status = 'Sold'
GROUP BY pid
union
select projects.name as projects, projects.id as pid,
concat(users.f_name, ' ', users.l_name) as agent,
SUM(units.price) AS topagent
from projects left outer join types on projects.id = types.project_id
left outer join units on types.id = units.types_id and units.status = 'Sold'
left outer join bookings on units.id = bookings.unit and units.status = 'Sold'
left outer join users on bookings.agent_id = users.id and units.status = 'Sold'
group by pid
) a
GROUP BY pid
order by topagent desc
Try it if helps you-
SELECT a.prjname, IFNULL(usr.name,'-') AS Top_Agent, SUM(a.sale) AS Total_Sales_for_Project
FROM
(
SELECT prj.id AS prjid,prj.name AS prjname,usr.id,usr.name AS usrname,IFNULL(SUM(unit.price),0) AS sale
FROM projects AS prj
LEFT JOIN `types` AS typ ON typ.project_id=prj.id
LEFT JOIN units AS unt ON unt.type_id=typ.id AND unt.status='sold'
LEFT JOIN bookings bkg ON bkg.unit=unt.id
LEFT JOIN users usr ON usr.id=bkg.agent_it
GROUP BY prj.id,usr.id
ORDER BY prj.id,usr.id,sale DESC
) a
GROUP BY a.prjid
Your column aliases are confusing to read. In English, it seems what you mean by topagent is "sum of sales by a human". But in SQL, your GROUP BY pid means that the SUM(units.price) really means "sum of sales in a project".
Then the UNION adds a list of projects to a list of users. The agent names are basically random at this point.
If I decipher the requirements as "a list of projects ranked by the sales values of each project's top sales agent", then you'd have SQL as below:
SELECT
pid,
projects.name as project_name,
IFNULL(a.top_agent_name,'-') as top_agent_name,
CASE WHEN FORMAT(top_agent_sales,0) > 0 THEN FORMAT(top_agent_sales,0) ELSE 0 END as top_agent_salesvolume
FROM
projects
JOIN
SELECT
a.pid,
a.agent_name as top_agent_name,
a.agent_sales as top_agent_sales
FROM
(SELECT
projects.id as pid,
concat(users.f_name, ' ', users.l_name) as agent_name,
SUM(units.price) AS agent_sales
FROM users
inner join bookings on bookings.agent_id = users.id
inner join units on bookings.unit = units.id
inner join types on types.id = units.types_id
inner join projects on projects.id = types.project_id
WHERE units.status = 'Sold'
GROUP BY pid, users.id
) a # get all agents for all projects
JOIN
(SELECT
MAX(agent_sales) as max_project_agent_sales
FROM
(SELECT
projects.id as pid,
SUM(units.price) AS agent_sales
FROM users
inner join bookings on bookings.agent_id = users.id
inner join units on bookings.unit = units.id
inner join types on types.id = units.types_id
inner join projects on projects.id = types.project_id
WHERE units.status = 'Sold'
GROUP BY pid, users.id
)
GROUP BY pid) b ON a.pid = b.pid
WHERE
a.agent_sales = b.max_project_agent_sales
ORDER BY a.agent_sales desc
Old answer below:
There are 2 topagents for each pid in the inner query since it's a union of 2 group bys. There isn't a reducing function in the outer group by pid so the topagent returned in the select is the first one that came up in the inner query.