Course Content
Intermediate SQL
2. Nested Subqueries
4. Left, Right, and Inner Joins
Intermediate SQL
Challenge: Number of Stations
Note
COUNT(column)is the function that counts the number of rows.
Task
Using the relation table, find the number of stations (create a new column, named number_of_stations using station_name and COUNT() function) for each of the lines (line_name).
Here's a short example of the relation table:
| relation_id | line_name | station_name | time_to_next_station |
| 1 | Green | Angrignon | 10 |
| 2 | Green | Monk | 16 |
| 3 | Green | Verdun | 9 |
| ... | ... | ... | ... |
| 21 | Yellow | Longueuil | 10 |
Everything was clear?
Section 1. Chapter 2
