DECLARE @sql VARCHAR(8000)
SET @sql = 'select A3'
SELECT  @sql = @sql + '  ,max(case A1 when ''' + A1
        + ''' then A2 else 0 end) [' + A1 + ']'
FROM    ( SELECT DISTINCT
                    A1
          FROM      Table_1
        ) AS a
SET @sql = @sql + ' from Table_1 group by A3'
EXEC(@sql) 

declare 
var_sql_str varchar2(2000);
type test_array is table of Table_1.A1%type INDEX BY BINARY_INTEGER;
 var_test_array test_array;
 begin 
 select distinct A1  bulk collect into var_test_array from Table_1;
 var_sql_str:='select A3'
 for i in 1..var_test_array.count loop
 begin
 var_sql_str:=var_sql_str||', max(case A1 when '''||var_test_array(i)||''' then A2 else 0 end) as '||var_test_array(i)||''
 end loop;
 var_sql_str:=var_sql_str||' from Table_1 group by A3'
 execute immediate var_sql_str;
 end ;