Use a Self Join and display the last name of each Instructor and the last name of their Department Chair. Label each column

Assuming you are using SQL and you have a table named "Instructors" with columns "LastName", "FirstName", "Dept", and "IsDeptChair", you can use a self join to display the last name of each instructor and the last name of their department chair. Here's how you can do it:

SELECT I1.LastName AS 'Instructor', I2.LastName AS 'Department Chair'
FROM Instructors I1
JOIN Instructors I2 ON I1.Dept = I2.Dept
WHERE I2.IsDeptChair = 1

Here's the step by step explanation:

1. SELECT I1.LastName AS 'Instructor', I2.LastName AS 'Department Chair': This line is selecting the last names of the instructors and department chairs. The 'AS' keyword is used to rename the columns in the output.

2. FROM Instructors I1: This line is specifying the table we are selecting data from. 'I1' is an alias for the 'Instructors' table.

3. JOIN Instructors I2 ON I1.Dept = I2.Dept: This line is performing a self join on the 'Instructors' table. It's joining the table to itself on the condition that the department of the first instance of the table (I1) is the same as the department of the second instance of the table (I2).

4. WHERE I2.IsDeptChair = 1: This line is filtering the results to only include rows where the instructor is a department chair.

Please note that this query assumes that there is only one department chair per department. If there can be multiple department chairs, you might need to adjust the query accordingly.