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Joseph Saliba
Java Web Development Techdegree Student 1,862 Pointsit's not obvious what's wrong though am answering and the result is showing in preview
help plz
2 Answers
Joseph Saliba
Java Web Development Techdegree Student 1,862 Pointshttps://teamtreehouse.com/library/reporting-with-sql/aggregate-and-numeric-functions/counting-groups
In the library database there's a books table. There are id, title, author, genre and first_published columns. Count all the books in each genre. Include the genre column first and the genre_count as the second column of information.
select genre, count(genre) as genre_count from books group by genre
Jason Anello
Courses Plus Student 94,610 PointsWhen you run that query you'll notice that the first row has a null genre and the count is 0. But there must have been at least one row with a null genre for that to even show up.
The problem is that count(genre) will only count non-null values.
count(*) will count null genres as well.
If you run it with that then you'll see that the count is 1 for missing genres.
You can run the query select * from books and you'll be able to see row 20, I think, is the only row with a missing genre.
Jason Anello
Courses Plus Student 94,610 PointsJason Anello
Courses Plus Student 94,610 PointsHi Joseph,
Can you link to the challenge you're on as well as post the query you're trying?