How to get checkbox value in apex application

i created the following pl/sql code in order to obtain the value of the checked row.

BEGIN
FOR I in 1..APEX_APPLICATION.G_F01.COUNT LOOP
 UPDATE TEST_CHECK_STATUS 
 SET check_status = 1
 WHERE rowid = APEX_APPLICATION.G_F02(APEX_APPLICATION.G_F01(I));
END LOOP;
END;

When execute this code i obtain this error:

ORA-06550: line 6, column 16: PLS-00103: Encountered the symbol "BEGIN" when expecting one of the following: ( - + case mod new not null continue avg count current exists max min prior sql stddev sum variance execute forall merge time timestamp interval date pipe

someone tell me where is the error?