Think the output shown in video for "WHERE NOT EXISTS" is incorrect. It should fetch 2 values instead of 1. It should be "Magical Products" and "Amazing Stuff" as both of them have items less than 1 $
You may have misheard the question, which was to find the suppliers that “do not provide ANY products more expensive than a dollar” “Amazing Stuff”, has a product called “Chewing Gum” that costs more than a dollar
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This book could help ... Data Science and Engineering - A learning path - Volume 4 Relational and non-relational databases and SQL: with applications in MySQL, SQLite and Orange Data Mining
This book could help ... Data Science and Engineering - A learning path - Volume 4 Relational and non-relational databases and SQL: with applications in MySQL, SQLite and Orange Data Mining
Good overview. Thanks. I'd like to add one thing to keep in mind. It seems easy to consider this and use is null instead. However the pitfall is, when you compare against a column value (e.g. in a join), where null values exist. Or when you use optional user inputs and try something like this: tbl.col = NVL({input}, tbl.col) When this columns contains nulls then this becomes tbl.col = null what fails. (Here the solution could be tbl.col = {input} or {input} is null) The danger is, when you get a good looking resultset and don't recognize, that you compare against null!
Just wanted to get a brush up on some SQL topics, and your video was really helpful. But please, please do not put music on such a lecture video. It is really disturbing the purpose of the instructor, most of the words were not audible.
Thank you for the explanation but please can you reduce the background sound in subsequent videos, it was overshadowing your voice and was quite distracting. Thanks again
(This course is very technical to listen in english (because i'm french) it looks very interesting but really the music in the background is really disturbing .. i can't listen)
I couldn't still get it. So , what is the real function of this exists though? If we, let's say remove it from your query sample, what will be fundamentally changed in the result set?
Great video! I just want to add that subqueries in the select statement are also referred to as 'subselects' and that a subselect query can reference columns in the select query. However, subqueries used in join cannot. Queries used in joins can also have multiple columns and are similar to a common table expressions (CTE). In SQL the only parts you need single-row unique columns are in: subselects and in where clause subqueries.