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SQL Exercise: A department 50 employee without a commission %

SQL SORTING and FILTERING on HR Database: Exercise-33 with Solution

33. From the following table, write a SQL query to find those employees who do not have commission percentage and have salaries between 7000, 12000 (Begin and end values are included.) and who are employed in the department number 50. Return all the fields of employees.

Sample table : employees


Sample Solution:

SELECT * 
	FROM employees 
		WHERE commission_pct IS NULL 
			AND salary BETWEEN 7000 AND 12000 
				AND department_id=50;

Sample Output:

employee_id | first_name | last_name | email | phone_number | hire_date | job_id | salary | commission_pct | manager_id | department_id
-------------+------------+-----------+-------+--------------+-----------+--------+--------+----------------+------------+-------------
(0 rows)

Code Explanation:

The said query in SQL that selects all columns (*) from the 'employees' table where the value in the "commission_pct" column is NULL, the value in the "salary" column is between 7000 and 12000, and the value in the "department_id" column is equal to 50. The resulting output will be all the rows from the "employees" table that meet the conditions as stated.

Relational Algebra Expression:

Relational Algebra Expression: Display the details of the employees who have no commission percentage and salary between 7000 to 12000 and works in department 50.

Relational Algebra Tree:

Relational Algebra Tree: Display the details of the employees who have no commission percentage and salary between 7000 to 12000 and works in department 50.

Practice Online


N.B.: In certain instances not null is removed in table structure, so results may vary.

HR database model

Query Visualization:

Duration:

Query visualization of Display the details of the employees who have no commission percentage and salary between 7000 to 12000 and works in department 50 - Duration

Rows:

Query visualization of Display the details of the employees who have no commission percentage and salary between 7000 to 12000 and works in department 50 - Rows

Cost:

Query visualization of Display the details of the employees who have no commission percentage and salary between 7000 to 12000 and works in department 50 - Cost

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Previous SQL Exercise: The date when he left his last job and his employee ID.
Next SQL Exercise: Jobs which average salary is above 8000.

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SQL: Tips of the Day

Difference between natural join and inner join

One significant difference between INNER JOIN and NATURAL JOIN is the number of columns returned-

Consider:

TableA                           TableB
+------------+----------+        +--------------------+    
|Column1     | Column2  |        |Column1  |  Column3 |
+-----------------------+        +--------------------+
| 1          |  2       |        | 1       |   3      |
+------------+----------+        +---------+----------+

The INNER JOIN of TableA and TableB on Column1 will return

SELECT * FROM TableA AS a INNER JOIN TableB AS b USING (Column1);
SELECT * FROM TableA AS a INNER JOIN TableB AS b ON a.Column1 = b.Column1;
+------------+-----------+---------------------+    
| a.Column1  | a.Column2 | b.Column1| b.Column3|
+------------------------+---------------------+
| 1          |  2        | 1        |   3      |
+------------+-----------+----------+----------+

The NATURAL JOIN of TableA and TableB on Column1 will return:

SELECT * FROM TableA NATURAL JOIN TableB
+------------+----------+----------+    
|Column1     | Column2  | Column3  |
+-----------------------+----------+
| 1          |  2       |   3      |
+------------+----------+----------+

Ref: https://bit.ly/3AG5CId

 





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