SELECT values of a column that are not in another column in the same table MySQL

Question

I have a sample table called "Quant1" as follows (ID - int PK, Name - Varchar(45), Salary - float, manager_id - int):

ID	Name	Salary	Manager_id
1	John	300	3
2	Mike	200	3
3	Sally	550	4
4	Jane	500	7
5	Joe	600	7
6	Dan	600	3
7	Phil	550	NULL

I want to list employees not managing anyone, i.e. ID 1,2,5,6.So I write the following code:

SELECT *
FROM quant1
WHERE id NOT IN 
    (SELECT DISTINCT manager_id
    FROM quant1);

But it doesn't result in the desired outcome. Can anyone spot the error in my script? Thanks in advance!

Answer 1

This query will return all the rows from the table_name table where the column_name column is not contained in the column_name column from the table_name table.

SELECT * FROM table_name 
WHERE column_name NOT IN 
(
 SELECT column_name FROM table_name
)

Answer 2

SELECT *
FROM quant1
WHERE id NOT IN 
    (SELECT DISTINCT manager_id
    FROM quant1 WHERE manager_id IS NOT NULL);

Answer 3

You have to exclude the NULL manager ID from the subquery, because all comparisons with NULL fail.

SELECT *
FROM quant1
WHERE id NOT IN 
    (SELECT DISTINCT manager_id
    FROM quant1
    WHERE manager_id IS NOT NULL);

DEMO