SQL & PL/SQL

I am using 10g Release 10.2.0.1.0

I've the following table and wanted to flip table horizontally in such a way that for each key if there is a s_key and type_cd, then it checks another table if that column exist in it or not?
if the column doesnt exist, then it should create a new column in another table.

Table_A

KEY    S_KEY    TYPE_CD 

191    100   A    
191    50    A    
191    70    A    
191    70    C 
100    10    A
100    20    C

flip it is this manner

skey_100  skey_50  skey_70  type_A  type_C
skey_10    skey_20 type_A  type_C

Lets only look at KEY 191.
now i want to check another table TABLE_B if ( columns skey_100 , skey_50, skey_70, type_A, type_C are present) if not then add to that table with datatype varchar2(10)

here is my effort

FOR c IN (SELECT DISTINCT S_KEY, TYPE_CD 
             FROM TABLE_A
             WHERE KEY = 191
             )
             
              LOOP
                 BEGIN
                 
                        SELECT distinct skey, type_cd
                              INTO c_column_name
                        FROM all_tab_columns a
                        WHERE owner = 'STG'
                        AND table_name = 'TABLE_A'
                        AND column_name = 'SKEY_'||c.S_KEY ; 
     
                       EXCEPTION WHEN NO_DATA_FOUND THEN
                       EXECUTE IMMEDIATE 'ALTER TABLE TABLE_A ADD ' 
                                        || 'SKEY_'||c.S_KEY
                                        || ' VARCHAR(10)';
                 END;
              END LOOP;

I dont know how to do both the colums together..


Thanks