SQL & PL/SQL

Hello,

I need to calculate the running balance of an account by adding a figure at the start of the month and then adding daily closing balances.

create table table1(
   Acct  varchar2(16),
   trans_date date,
   closing_bal number(19,3)
   )
   ; 
   
    insert into table1 values('ACCT1', '24-JAN-19', 242.5);
    insert into table1 values('ACCT1', '28-JAN-19', -300);
    
COMMIT;

So at the start of the month, if balance is 425.128, I need the result like below: