我可以根据条件将值插入列吗？ SQL Server

Question

我想知道我怎么能，例如，如果我有：

Employees:  nameOfEmployee,numberOfEmployee,numberOfDepartment,....,....,....,....,...,....,....
Departments:  numberOfDepartment,numberOfEmployees,....,....,....,....,...,....,....

并且表中已有行，通过添加nameOfEmployee来填充Departments.numberOfEmployees中的值

到目前为止，我唯一想到的就是：

UPDATE Departments
SET numberOfEmployees=COUNT(Employees.nameOfEmployee)
FROM Employees
WHERE Departments.numberOfDepartment=Employees.numberOfDepartment

我知道这可能甚至没有任何意义。我刚刚开始使用SQL

Answer 1

试试这个（UNTESTED）

UPDATE Departments
SET numberOfEmployees=(SELECT COUNT(Employees.nameOfEmployee)
FROM Employees
WHERE Departments.numberOfDepartment=Employees.numberOfDepartment)