Database Foundations Joining Relational Data Between Tables in SQL Joining Tables and Aliasing Challenge

you use wrong key to match the two tables

ummm. hello?? you never answered me

I'm bumping into the same roadblocks as Wendell here.. would appreciate if anyone could help shed some light.. thanks!

Basically you have to look at the question CAREFULLY, You have the first part right, joining the movies.title first and the genres.name second,

SELECT movies.title, genres.name FROM movies INNER JOIN

The next part is tricky, you're naming the wrong keys. Notice in the question that there are two different columns for each table, you have to replace the ON movies.title = genres.name with the other columns listed that you're not trying to list first and second. I'm horrible at explaining and it was a struggle for me as well but I hope that helps.

Correct answer:

SELECT movies.title, genres.name FROM movies JOIN genres ON movies.genre_id = genres.id;

I had to read the entry on JOIN syntax from the W3C to wrap my head around this: http://www.w3schools.com/sql/sql_join.asp

First, select the "title" column from the movies table & the "name" column from the genres table:

SELECT movies.title, genres.name

Then, specify which two tables you're joining information from:

FROM movies JOIN genres

Lastly, and this one is tricky, you must select the columns from the tables that refer to one another:

ON movies.genre_id = genres.id;

Which means, "the genre_id column from the movies table refers to the id column in the genres table". That is, the number assigned to each movie as its "genre_id" corresponds to the same number in the genres table which is just called "id". The ON keyword lets you join the tables by specifying which columns from each table refer to one another.

Does that help? I find that even though I mostly understand it that it's still difficult to describe because, like most syntax, it's convoluted.