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Jacinda Zhong
3,695 PointsMySQL left and right join question
Hello, I don't quite understand left/right joining - wouldn't left joining just return the entire contents of one table, and right joining would return all contents of the other table? What am I missing here?
1 Answer
Dave McFarland
Treehouse TeacherThe outer joins return the data from one table + the data from another table that joins with the first. In the case of a left outer join, ALL the data from the first table listed in the query is returned with JUST the data from the second table that joins with the first table. If you watch this video again http://teamtreehouse.com/library/database-foundations/joining-relational-data-between-tables-in-sql/-joining-tables-and-aliasing it might make sense.
At the 2:40 mark in that video Andrew shows a diagram that I think makes the relationship clear.