Not able to update tables using Anonymous block in PLSQL

Hello Experts,

Oracle DB version: 11.2.0.1

we are trying to update the tables as per below details using anonymous block but tables are not getting updated,

Creation and Insertion Scripts:

create table table_a(id number,quantity number, item_id number)

/

create table table_b(id number,item_id number,vendor_name varchar2(250),percentage number, percentage_value number)

/

create table table_c(id number,quantity number, item_id number,process_flag varchar2(3))

/

insert into table_a values(123,1000,635)

/

insert into table_b values(123,635,'ABC1',65,500)

/

insert into table_b values(123,635,'ABC2',35,500)

/

insert into table_c values(123,1000,635,'N')

/

commit

/

Function:

CREATE OR REPLACE FUNCTION test1_func (