Alter table then Update in PL/SQL block

Question

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.

Answer 1

Yes, you are absolutely right, I shouldn't alter the table and then update the values.
The reason I need to do it relates to the migration process we utilize in our company. Initially I had a set of SQL commands which I executed migrating from one environment to another and eventually to Production. I had an error in the last SQL command which caused migration process to produce "Failure", however the table was already altered and all the rows except the last one were updated. Since I can't successfully migrate to Production with the failed process I have to generate a PL/SQL block which will take in consideration that in one environment the table has already been modified and in the other one is still needs to be changed.