Why getting a Syntax error in MySQL Trigger query? - mysql

Question

I have learned the triggers in Oracle SQL, and not that well versed in MySQL. I was trying to convert a trigger command from Oracle to MySQL. First of all, I am not able to find the when statement, I found the if else instead. This is what I wrote:
create trigger overdraft
after update on account
for each row
begin
if account.balance < 0 then
insert into borrower(select customer_name, account_number from depositor where new.account_number=depositor.account_number);
insert into loan(select new.account_number, new.branch_name, new.balance);
update account set balance = 0 where account.account_number = new.account_number;
end if;
end;
But I am getting three syntax errors, first at end of first insert statement at the left parenthesis saying, "Statement is incomplete, expecting : ','". Other two are on each of the ends saying "end is not valid at this position: Expecting BEGIN, EOF,....". What is wrong with me code? I am having hard time figuring out.

Answer 1

There are several things. delimiter probably being one of them:
delimiter $$
create trigger overdraft before update on account
for each row
begin
if new.balance < 0 then
insert into borrower (customer_name, account_number) -- column list here
select d.customer_name, d.account_number
from depositor d
where new.account_number = d.account_number;
insert into loan (account_number, branch_name, balance) -- column list here
select new.account_number, new.branch_name, new.balance;
set new.balance = 0;
end if;
end;$$
delimiter ;
Notes:
delimiter is needed so the definition of the trigger does not end at the first semi-colon.
The reference in the initial if (account.balance) is not understood, because account is not defined.
You want to update the balance in the row with the trigger. Hence, you want a before update trigger, not an after update trigger.
When inserting rows into a table, you should always list the columns being inserted. I have speculated on the column names above.

Answer 2

Simply use Delimiter like this.
I thought that you had tested all the insert.
Inser ino mus be like the example wthat i written,but the columnnames could differ.
As i described you can't use the same table in your trigger that fired the trigger. so use the set paramter to change the balance to 0
DELIMItER //
create trigger overdraft
after update on account
for each row
begin
if account.balance < 0 then
insert into borrower (customer_name, account_number) select customer_name, account_number from depositor
where new.account_number=depositor.account_number;
insert into loan (account_number, branch_name, balance) select new.account_number, new.branch_name, new.balance;
set new.balance = 0;
end if;
end;
DELIMItER ;