SQL Exercise: Count the number of available rooms in each floor
SQL hospital Database: Exercise-23 with Solution
23. From the following table, write a SQL query to count the number of available rooms in each floor. Sort the result-set on block floor. Return floor ID as "Floor" and count the number of available rooms as "Number of available rooms".
Sample table: room
Sample Solution:
SELECT blockfloor AS "Floor",
count(*) "Number of available rooms"
FROM room
WHERE unavailable='false'
GROUP BY blockfloor
ORDER BY blockfloor;
Sample Output:
Floor | Number of available rooms -------+--------------------------- 1 | 8 2 | 7 3 | 7 4 | 7 (4 rows)
Explanation:
The said query in SQL that retrieves the number of available rooms on each floor of a block in a building.
This query counts the number of rows that satisfy the WHERE condition, and the WHERE clause filters to include only rows where the unavailable column is 'false'.
The GROUP BY clause groups the data by the blockfloor column, so that the count of available rooms is computed for each distinct floor.
The ORDER BY clause sorts the output by the blockfloor column in ascending order.
Practice Online
E R Diagram of Hospital Database:

Have another way to solve this solution? Contribute your code (and comments) through Disqus.
Previous SQL Exercise: Count the number of available rooms in each block.
Next SQL Exercise: Count the number of rooms in each block on each floor.
What is the difficulty level of this exercise?
Test your Programming skills with w3resource's quiz.
SQL: Tips of the Day
Grouped LIMIT in PostgreSQL: Show the first N rows for each group?
db=# SELECT * FROM xxx; id | section_id | name ----+------------+------ 1 | 1 | A 2 | 1 | B 3 | 1 | C 4 | 1 | D 5 | 2 | E 6 | 2 | F 7 | 3 | G 8 | 2 | H (8 rows)
I need the first 2 rows (ordered by name) for each section_id, i.e. a result similar to:
id | section_id | name ----+------------+------ 1 | 1 | A 2 | 1 | B 5 | 2 | E 6 | 2 | F 7 | 3 | G (5 rows)
PostgreSQL v9.3 you can do a lateral join
select distinct t_outer.section_id, t_top.id, t_top.name from t t_outer join lateral ( select * from t t_inner where t_inner.section_id = t_outer.section_id order by t_inner.name limit 2 ) t_top on true order by t_outer.section_id;
Database: PostgreSQL
Ref: https://bit.ly/3AfYwZI
- Weekly Trends
- Python Interview Questions and Answers: Comprehensive Guide
- Scala Exercises, Practice, Solution
- Kotlin Exercises practice with solution
- MongoDB Exercises, Practice, Solution
- SQL Exercises, Practice, Solution - JOINS
- Java Basic Programming Exercises
- SQL Subqueries
- Adventureworks Database Exercises
- C# Sharp Basic Exercises
- SQL COUNT() with distinct
- JavaScript String Exercises
- JavaScript HTML Form Validation
- Java Collection Exercises
- SQL COUNT() function
- SQL Inner Join
We are closing our Disqus commenting system for some maintenanace issues. You may write to us at reach[at]yahoo[dot]com or visit us at Facebook