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Start your free trialdrstrangequark
8,273 PointsStill having issues with Joins
In SQL Playgrounds for Beginner SQL -> Querying Relational Databases -> Subqueries -> Review and Practice, the second assignment is:
-- Generate a report that lists a patron's first name, email and loan count for loans that haven't been returned.
This time, I'm unsure what I'm doing wrong. It tells me there is a syntax error near "INNER" but I'm still pretty lost. My query is:
SELECT patrons.first_name, patrons.last_name, patrons.email, COUNT(*) FROM ( SELECT * FROM loans_north UNION ALL SELECT * FROM loans_south ) AS total_loans WHERE returned_on IS NULL INNER JOIN patrons ON patrons.id = total_loans.id GROUP BY patron_id;
1 Answer
Steven Parker
231,269 PointsYou were pretty close the first time, and had a good idea about having the WHERE
outside of the subquery but it needed to come after the JOIN
:
-- Generate a report that lists a patron's first name, email and loan count
-- for loans that haven't been returned.
SELECT first_name, email, COUNT(1) AS "loan count"
FROM (SELECT * FROM loans_north UNION ALL SELECT * FROM loans_south) AS total_loans
INNER JOIN patrons ON patrons.id = total_loans.patron_id
WHERE returned_on IS NULL
GROUP BY patron_id;
drstrangequark
8,273 Pointsdrstrangequark
8,273 PointsNEVERMIND! I think I got it:
SELECT p.id AS "Patron ID", p.first_name AS "First Name", p.last_name AS "Last Name", p.email AS "Email", COUNT(*) AS "Unreturned Loan Count" FROM
( SELECT * FROM loans_north WHERE returned_on IS NULL
UNION ALL
SELECT * FROM loans_south WHERE returned_on IS NULL) AS total_loans
INNER JOIN patrons AS p ON p.id = total_loans.patron_id
GROUP BY p.id;
I'm sure that it can be cleaned up a bit but it got me the info I needed!