SQL Server 2019

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Create Table dbo.Employee(EmployeeID INT,EmployeeName VARCHAR(100), EmployeeDeptID INT)
insert into Employee select 1,'Person 1', null
insert into Employee select 2,'Person 2', null
insert into Employee select 3,'Person 3', null
insert into Employee select 4,'Person 4', null
4 rows affected

with v as (
	select v, Row_Number() over(order by NewId()) Id
	from (values(2010),(2590),(2877),(null))x(v)
), e as (
	select *, Row_Number() over (order by EmployeeId) Id
	from Employee
), u as (
	select e.EmployeeDeptID, v.v 
	from v join e on e.Id = v.Id
)
update u set employeeDeptId = v
4 rows affected

select * from Employee


EmployeeID
EmployeeName
EmployeeDeptID


1
Person 1
2010

2
Person 2
2877

3
Person 3
null

4
Person 4
2590