insert or update in postgresql 9.1 - postgresql

Question

I have a bunch of insert statements with varying number of columns for their respective tables, i need to execute these queries if the record doesn't already exist.I have tried to implement this as
do $$
begin
IF not exists (SELECT 1 FROM gst_type_customer WHERE name = 'Unregistered') THEN
insert into gst_type_customer(create_date,write_date,create_uid,write_uid,name) values((now() at time zone 'UTC'),(now() at time zone 'UTC'),1,1,'Unregistered');
END IF;
end
$$
even though the above code does work although implementing for a bulk of queries would require a lot of time, so i thought of making a stored procedure which i could call as
merge_check(insertquery,name[column to check for duplication],value)
but I'm unable to execute the insert query directly.
so far I have come up with
CREATE OR REPLACE FUNCTION merge_tabla(data text)
RETURNS void AS
$BODY$
BEGIN
execute(data);
END;
$BODY$
LANGUAGE plpgsql
select merge_table("insert into gst_type_customer(name) values('Unregistered')")
but I get an error saying
column "insert into gst_type_customer(name) values('Unregistered')" does not exist

Answer 1

The error You are getting is caused by using double quotes when calling the function. This should work:
select merge_table(E'insert into gst_type_customer(name) values(\'Unregistered\')'::text)
You need to use single quotes (double quotes are used for column names, single quotes for string literals) and escape any single quotes in the original query string.

Answer 2

You can use INSERT ... SELECT like this:
INSERT INTO gst_type_customer(create_date, write_date, create_uid, write_uid, name)
SELECT (now() at time zone 'UTC'), (now() at time zone 'UTC'), 1, 1, 'Unregistered'
WHERE NOT EXISTS (
SELECT *
FROM gst_type_customer
WHERE name = 'Unregistered'
)

Answer 3

postgres 9.1 supports merge command
https://www.postgresql.org/message-id/attachment/23520/sql-merge.html
sample:
MERGE CustomerAccount CA
USING (SELECT CustomerId, Sum(TransactionValue) As TransactionSum
FROM Transactions
WHERE TransactionId > 35345678
GROUP BY CustomerId) AS T
ON T.CustomerId = CA.CustomerId
WHEN MATCHED
UPDATE SET Balance = Balance - TransactionSum
WHEN NOT MATCHED
INSERT (CustomerId, Balance)
VALUES (T.CustomerId, T.TransactionSum)
;