updating data after adding new column in a sigle T-SQL block

Note that the Emlpoyee table is having two columns such as EMPNAME, EMPID...

   
CREATE TABLE EMPLOYEE ( EMPID INT identity(1,1), EMPNAME varchar(100))
INSERT EMPLOYEE values( 'Chandu'),( 'Chandu2'),( 'Chandu3'),( 'Chandu4')

Now i wanted to add new column EMPLOYER and then add data to it

BEGIN 
    Alter TABLE EMPLOYEE  ADD EMPLOYER VARCHAR(50);
    UPDATE EMPLOYEE SET EMPLOYER=EMPNAME 
END

It gives the below error,
Msg 207, Level 16, State 1, Line 3
Invalid column name 'EMPLOYER'.

to resolve this error, we need to update tables data using Dynamic SQL query in the case of updating data after adding column in the SINGLE block

   BEGIN 
    Alter TABLE EMPLOYEE  ADD EMPLOYER VARCHAR(50);
	EXEC ( 'UPDATE EMPLOYEE SET EMPLOYER=EMPNAME ')
   END