PostgreSQL Basic SELECT Statement: Get unique department ID from employee table
2. Write a query to get a unique department ID from employee table.
Sample Solution:
Code:
SELECT DISTINCT department_id
FROM employees;
Sample table: employees
Output:
pg_exercises=# SELECT DISTINCT department_id pg_exercises-# FROM employees; department_id --------------- 90 20 100 40 110 80 70 50 60 30 10 0 (12 rows)
Relational Algebra Expression:
Relational Algebra Tree:
Practice Online
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Previous: Write a query to display the names (first_name, last_name) using an alias name "First Name", "Last Name".
Next: Write a query to get the details of all employees from the employee table in descending order by their first name.
What is the difficulty level of this exercise?
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