Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

Databases Querying Relational Databases Subqueries Subqueries

Ikechukwu Arum
Ikechukwu Arum
5,337 Points
Posted by Ikechukwu Arum
Ikechukwu Arum
5,337 Points

related to the subquery challenge using the "IN" Keyword

In a car database there is a Model table with columns, ModelID, MakeID and ModelName and a Car table with columns, CarID, ModelID, VIN, ModelYear and StickerPrice. Use a subquery along with IN to list all the Model Names with a Sticker Price greater than $30000

SELECT ModelName FROM MODEL WHERE ModelID IN (SELECT ModelID FROM CAR WHERE stickerPrice >30000);

I was able to solve this problem using the code above. however I am confused as to why I am not able subquery the "Model" table instead. Below are the codes I've tried:

The code below give me errors because of "modelname" 

SELECT  ModelName, ModelID, stickerPrice FROM car WHERE stickerPrice >30000 AND ModelID IN(SELECT ModelID From Model);

The code below gives me error because of the alias.

SELECT  M.ModelName, ModelID, stickerPrice FROM car WHERE stickerPrice >30000 AND ModelID IN(SELECT ModelID From Model) AS M;

Can anyone please explain if it can be done and how?

1 Answer

Steven Parker
Steven Parker
229,644 Points
Steven Parker
Steven Parker
229,644 Points

The second example has two issues:

  • SELECT ModelName ... FROM car :point_left: the "car" database has no "ModelName" field
  • ... ModelID IN (SELECT ModelID from Model) :point_left: will always be true, so it won't filter anything

And for the last example, there's also two issues:

  • for "M" to be a data source for the SELECT, it must appear in a FROM or JOIN clause
  • you can't give an alias to a subquery in a WHERE clause
Ikechukwu Arum
Ikechukwu Arum
5,337 Points
Ikechukwu Arum
Ikechukwu Arum
5,337 Points

thanks, i was getting a subqery with an"IN" statement confused with a subquery using a "join" statement