Case

%LOAD ../data/employees.db

CASE werkt als een if-then-else constructie. Maar in plaats van if wordt when gebruikt.

SELECT last_name,
CASE department_id
 WHEN 90 THEN 'Management'
 WHEN 80 THEN 'Sales'
 WHEN 60 THEN 'IT'
 ELSE 'Other department'
END AS department
FROM employees;

last_name	department
King	Management
Kochhar	Management
De Haan	Management
Hunold	IT
Ernst	IT
Lorentz	IT
Mourgos	Other department
Rajs	Other department
Davies	Other department
Matos	Other department
Vargas	Other department
Zlotkey	Sales
Abel	Sales
Taylor	Sales
Grant	Other department
Whalen	Other department
Hartstein	Other department
Fay	Other department
Higgins	Other department
Gietz	Other department

---

Te doen

Er wordt hier een vergelijking met IF gemaakt; maar heb je die in SQL? Hoe zouden leerlingen die moeten kennen?

SELECT CAST(round(100.8) AS INT);

CAST(round(100.8) AS INT)
101

SELECT round(100.8);

round(100.8)
101.0

SELECT '100.8';

'100.8'
100.8