Copy one column value to another for all rows in SQL Server

Hi,

Please refer below script

SQL

DECLARE @temp AS TABLE(empId INT,email VARCHAR(100),employeemail  VARCHAR(100))

INSERT INTO @temp VALUES(1,'abc@gmail.com',null),
(2,'bbc@gmail.com',null)

SELECT * FROM @temp

UPDATE @temp 
SET employeemail = email 
FROM @temp t1 
WHERE t1.empId = empId

SELECT * FROM @temp

Output