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Paul Ownby
23,414 PointsI cannot get a correct answer for Task #4 on the last Challenge for Querying Relational Databases. What's wrong?
On task #4 of the last coding challenge, I am getting an error but I have confirmed by manually looking and comparing both tables that the table returned is correct. What am I missing?
Error: Bummer! The subquery didn't return all CustomerIDs for people who identify as female (F).
Query: SELECT s.SaleID, s.CarID, s.CustomerID, s.LocationID, s.SalesRepID, s.SaleAmount, s.SaleDate FROM Sale AS s INNER JOIN ( select * from Customer c where c.Gender = "F" ) AS cust ON cust.CustomerId = s.CustomerId
URL: https://teamtreehouse.com/library/querying-relational-databases/subqueries/subqueries
2 Answers
Steven Parker
229,732 PointsYou might be working too hard.
Try simplifying the query, remove unneeded aliases and select only the field you need in the subquery.. Something like this:
SELECT * FROM Sale AS s
INNER JOIN (SELECT CustomerID FROM Customer where Gender = "F") AS cust
ON cust.CustomerId = s.CustomerId;
Christian Scherer
2,989 PointsHi Steven,
Thank you for your answer which helped me to complete this task.
Question: I had the exact same code BUT used SELECT s.* FROM Sale AS s... Which did not work.
Any idea why I cant use the Alias "s" at this point?
Steven Parker
229,732 PointsSpecifying "s.*" instead of "*" would display only the columns from the Sale table and would omit the joined field.
Paul Ownby
23,414 PointsPaul Ownby
23,414 PointsThanks Steven. Unfortunately, that doesn't work either. I even tried s.* in the select as the requirement is to only return columns from the Sale table and it is still is giving the same error. I think this might be a bug.
I just tried it again and now it works. Weird. Thanks for the help!
Steven Parker
229,732 PointsSteven Parker
229,732 PointsThat's very odd because if I copy that query from the box above and paste it directly into the challenge (for task 4), it passes.
Paul Ownby
23,414 PointsPaul Ownby
23,414 PointsI found the difference. I was using select * in the subquery. I suspect that that was not an acceptable answer because the subquery was returning more rows that it needed to complete the query. Changing * to CustomerId did the trick. Thanks again Steven!