PROBLEM LINK:
DIFFICULTY:
TBD
PREREQUISITES:
Basic SQL
PROBLEM:
Print the number of distinct entries in a column
EXPLANATION:
DISTINCT returns only the distinct entries, and COUNT gives you the number of rows in that. Hence, that solves the problem.
And remember to have the column alias set correctly.
Code
SELECT COUNT (DISTINCT(institution)) AS 'Number of Distinct Insti'
FROM Participants;