SQL Exercise: Count the number of rooms in each block on each floor

SQL hospital Database: Exercise-24 with Solution

24. From the following tables, write a SQL query to count the number of available rooms for each floor in each block. Sort the result-set on floor ID, ID of the block. Return the floor ID as "Floor", ID of the block as "Block", and number of available rooms as "Number of available rooms".

Sample table: room

Sample Solution:

SELECT blockfloor AS "Floor",
       blockcode AS "Block",
       count(*) "Number of available rooms"
FROM room
WHERE unavailable='false'
GROUP BY blockfloor,
        blockcode
ORDER BY blockfloor,
        blockcode;

Sample Output:

 Floor | Block | Number of available rooms
-------+-------+---------------------------
     1 |     1 |                         3
     1 |     2 |                         2
     1 |     3 |                         3
     2 |     1 |                         2
     2 |     2 |                         2
     2 |     3 |                         3
     3 |     1 |                         2
     3 |     2 |                         3
     3 |     3 |                         2
     4 |     1 |                         2
     4 |     2 |                         3
     4 |     3 |                         2
(12 rows)

Explanation:

The said query in SQL that selects the blockfloor and blockcode columns and counts the number of available rooms by grouping the data by blockfloor and blockcode where the value of unavailable column is 'false'.

The WHERE clause filters the data by only selecting rows where the value of the unavailable column is 'false'.

The GROUP BY clause groups the data by blockfloor and blockcode, which allows the count of available rooms to be aggregated by these columns.

The ORDER BY clause orders the results by blockfloor and blockcode in ascending order.

Practice Online

E R Diagram of Hospital Database:

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