1789. Primary Department for Each Employee

Table: Employee +---------------+---------+ | Column Name | Type | +---------------+---------+ | employee_id | int | | department_id | int | | primary_flag | varchar | +---------------+---------+ (employee_id, department_id) is the primary key (combination of columns with unique values) for this table. employee_id is the id of the employee. department_id is the id of the department to which the e