WISE OWL EXERCISES
- Simple Queries (4)
- Setting criteria using WHERE (5)
- Calculations (7)
- Calculations using dates (4)
- Basic joins (8)
- More exotic joins (2)
- Aggregation and grouping (8)
- Views (5)
- Subqueries (5)
- Stored procedures (5)
- Variables (8)
- Parameters and return values (11)
- Testing conditions (1)
- Looping (3)
- Scalar functions (6)
- Transactions (5)
- Creating tables (5)
- Temporary tables and table variables (9)
- Table-valued functions (6)
- Derived tables and CTEs (13)
- Dynamic SQL (4)
- Pivots (2)
- Triggers (2)
- Archived (70)
SQL | Derived tables and CTEs exercise | Use a CTE to show enemies in certain Dr Who episodes
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First (if you haven't already done so) run the script shown above to generate the Doctor Who training database.
The aim of this exercise is to show a list of all of the enemies appearing in Doctor Who episodes featuring Rose Tyler, but not David Tennant.
It's possible - probable, even - that you could do this with a single SELECT statement, but CTEs make it so much easier to divide a complicated query into two simpler parts!
First create a query to show the episode id numbers for the 13 episodes which feature Rose Tyler as a companion, but not David Tennant as the Doctor.
Linking to this as a CTE, show the 8 enemies which appear in these episodes (some more than once):
The enemies corresponding to episodes featuring Rose Tyler, but not David Tennant.
Optionally, save this query as Wonderful CTEs.sql, then close it down.