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mysql - This correlated subquery example seems wrong

I found this example on https://sqlbolt.com/topic/subqueries enter image description here

Isn't the "dept_employees" on the last row of the query should refer to a table? From the row before it shows that it is a column.

I have tried to run it on MySQL and got "Error Code: 1054. Unknown column 'dept_employees.department' in 'where clause'"


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Perhaps it could be simplified to this but I do not know anything about MySQL.

SELECT *
FROM employees
WHERE salary >
(
    SELECT AVG(revenue_generated)
    FROM employees
    WHERE department = employees.department
)

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