SQL Query Involving Data From Different Tables - sql

Question

I have two different tables with records I need to join together in a way I can't quite figure out how to make work. My data looks like this.
Table A
Columns: Employee_ID, Employee_Department, Employee_Team, Manager_ID, Is_a_Manager ... many other columns
Sample Values:
12345 Department1 Team1 67890 Yes/No
.
.
.
One employee per row, several thousand rows comprising the entire company
Table B
Employee_ID, Manager_ID ... other columns
The exact same data set as Table A
Currently I'm combining those two tables (and three others) with a simple join on Employee_ID, which I'm then using as a data source in Tableau to visualize the data.
What I'd like to do with a SQL script is as follows:
Check to see whether an employee in Table A is a manager or not based on the Is_a_Manager column
If they are, find an employee in Table B who is one of their direct reports by matching the employee ID in Table A to the Manager ID in Table B.
Lookup that direct report's department and team in Table A by matching the Employee_ID in Table B to Employee_ID in Table A and displaying the Employee_Department and Employee_Team columns.
Add the direct report's department and team to two new columns in the original manager's Table A row
I'd like the final output in Table A to be something like
Employee_ID, Employee_Department, Employee_Team, Manager_ID, Is_a_Manager? ... Direct_Report_Department, Direct_Report_Team
Also, an important point is that some managers will have employees who are on different teams, so values in the Direct_Report_Department and Direct_Report_Team are not distinct. I only actually need any one employee's Department and Team to display, it doesn't matter which employee's it is.
Finally, I am able to do step 1 fairly easily in Tableau, so if the SQL script could do steps 2-4 and simply return a null value if the employee was not a manager, that would work for me as well.
Any ideas on how to accomplish this would be greatly appreciated. Thank you!

Answer 1

This should work based on the requirement provided. You don’t have to do any of the steps in Tableau and can simply export the output from the SQL as your data source
Select Tb1.Employee_ID, Tb1.Employee_Department, Tb1.Employee_Team, Tb1.Manager_ID, Tb1.Is_a_Manager, Tb3. Direct_Report_Department, Tb3. Direct_Report_Team
from Table_A Tb1
join (Select Manager_id, max(Employee_id) as emp_id from Table_B group by Manager_id) Tb2
on Tb1.Employee_id = Tb2.Manager_id
left join (Select Employee_ID, Employee_Department as Direct_Report_Department, Employee_Team as Direct_Report_Team from Table_A group by Employee_ID, Employee_Department, Employee_Team) Tb3
on Tb2.emp_id = Tb3.Employee_ID
where Tb1.Is_a_Manager = 'Yes';