how to fix this trigger error in PostgreSQL [duplicate] - sql

Question

This question already has answers here:
syntax Error in PostgreSQL when I try to create Trigger
(2 answers)
Closed last year.
I am getting a syntax error for my code which I can't understand why
am I missing something?
also, I read this I did not get my answer
syntax Error in PostgreSQL when I try to create Trigger
CREATE TRIGGER MyExampleName AFTER INSERT ON baskets
FOR EACH ROW BEGIN
UPDATE customers
SET customers.credit=customers.credit - NEW.amount
WHERE customers.id = NEW.customer_id;
END;
and tried it like this as well:
CREATE TRIGGER MyExampleName AFTER INSERT ON baskets
FOR EACH ROW AS $$ BEGIN
UPDATE customers
SET customers.credit=customers.credit - NEW.amount
WHERE customers.id = NEW.customer_id;
END;
$$ LANGUAGE plpgsql;
Error:
ERROR: syntax error at or near "BEGIN"
LINE 2: FOR EACH ROW BEGIN
^
SQL state: 42601
Character: 67

Answer 1

I'd say the first comment on your question pretty much covers it all. You cannot put the trigger code in the trigger body, you must first create a separate function and include the function call inside the trigger body.
This example comes directly from the Postgres docs:
-- 1. Create the function that does what you need
CREATE FUNCTION emp_stamp() RETURNS trigger AS $emp_stamp$
BEGIN
-- Check that empname and salary are given
IF NEW.empname IS NULL THEN
RAISE EXCEPTION 'empname cannot be null';
END IF;
IF NEW.salary IS NULL THEN
RAISE EXCEPTION '% cannot have null salary', NEW.empname;
END IF;
-- Who works for us when they must pay for it?
IF NEW.salary < 0 THEN
RAISE EXCEPTION '% cannot have a negative salary', NEW.empname;
END IF;
-- Remember who changed the payroll when
NEW.last_date := current_timestamp;
NEW.last_user := current_user;
RETURN NEW;
END;
$emp_stamp$ LANGUAGE plpgsql;
-- 2. Create the trigger with the 'EXECUTE FUNCTION function_name' part
-- replacing the actual function name from step 1.
CREATE TRIGGER emp_stamp BEFORE INSERT OR UPDATE ON emp
FOR EACH ROW EXECUTE FUNCTION emp_stamp();