SQL & PL/SQL

I am trying to alter the table then update it :

declare

colCount number;*

begin*


select count(*) into colCount from all_tab_cols where table_name = 'TEST' and owner = 'TEST_OWNER';*

dbms_output.put_line('No of Columns in the table : ' || colCount);*


if colCount = 2 then*


dbms_output.put_line('Table needs upgrade');*

execute immediate('ALTER TABLE TEST ADD COL1 VARCHAR2(100) NULL');*

UPDATE TEST SET COL1 = '123';*
commit;*
else*

dbms_output.put_line('No Changes Required');*

end if;*

end;*
Oracle complains that "COL1" is an invalid identifier.

I also tried substitute the UPDATE statement with

** execute immediate('UPDATE TEST SET VCHCHARSET_OUT='UTF8' WHERE VCHCHARSETNAME='UTF8'');**

and there is something wrong with the construction of an Update statement in the parenthesis.

Am I taking the right approach and just need to figuire out the syntax of single quotes or something else is wrong?

thanks in advance.