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MySQL Joins Exercises: Find the name and hire date of the employees who was hired after 'Jones'

MySQL Joins: Exercise-5 with Solution

Write a MySQL query to find the name (first_name, last_name) and hire date of the employees who was hired after 'Jones'.

Sample table: employees


Code:

-- This SQL query selects specific columns from the 'employees' table to retrieve information about employees hired after an employee with the last name 'Jones'.

SELECT 
    e.first_name, -- Selecting the 'first_name' column from the 'employees' table.
    e.last_name, -- Selecting the 'last_name' column from the 'employees' table.
    e.hire_date -- Selecting the 'hire_date' column from the 'employees' table.
FROM 
    employees e -- Specifying the 'employees' table and aliasing it as 'e'.
JOIN 
    employees davies -- Joining the 'employees' table again and aliasing it as 'davies'.
ON 
    (davies.last_name = 'Jones') -- Performing a join based on the condition where the last name in 'davies' is 'Jones'.
WHERE 
    davies.hire_date < e.hire_date; -- Filtering the result to include only employees hired after the employee with the last name 'Jones'.

Explanation:

  • This SQL query retrieves specific columns ('first_name', 'last_name', 'hire_date') from the 'employees' table.
  • The 'employees' table is referenced twice in the query, once as 'e' for the general employees and once as 'davies'.
  • It performs a join based on the condition where the last name in the 'davies' table is 'Jones'.
  • The WHERE clause filters the result to include only employees hired after the employee with the last name 'Jones', comparing their hire dates.

Relational Algebra Expression:

Relational Algebra Expression: Join: Find the name and hire date of the employees who was hired after 'Jones'.

Relational Algebra Tree:

Relational Algebra Tree: Join: Find the name and hire date of the employees who was hired after 'Jones'.

Sample Output:

first_name	last_name	hire_date
Alana		Walsh		1987-09-21T04:00:00.000Z
Kevin		Feeney		1987-09-22T04:00:00.000Z
Donald		OConnell	1987-09-23T04:00:00.000Z
Douglas		Grant		1987-09-24T04:00:00.000Z
Jennifer	Whalen		1987-09-25T04:00:00.000Z
Michael		Hartstein	1987-09-26T04:00:00.000Z
Pat		Fay		1987-09-27T04:00:00.000Z
Susan		Mavris		1987-09-28T04:00:00.000Z
Hermann		Baer		1987-09-29T04:00:00.000Z
Shelley		Higgins		1987-09-30T04:00:00.000Z
William		Gietz		1987-10-01T04:00:00.000Z

 

MySQL Code Editor:

Structure of 'hr' database:

hr database

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Previous:Write a MySQL query to find the employee id, name (last_name) along with their manager_id and name (last_name).
Next:Write a MySQL query to get the department name and number of employees in the department.

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