I have two tables employee and phones. An employee can have 0 to n phone numbers. I want to list the employee names with their phone numbers. I am using the below query which runs fine.
SELECT empname,array_agg(phonenumber) AS phonenumbers
FROM employee LEFT OUTER JOIN phones ON employee.empid = phones.empid
GROUP BY employee.empid
The employee table might contain large number of rows. I want to fetch only some employees at a time. For example I want to fetch 3 employees with their phone numbers. I am trying to run this query.
SELECT empname,array_agg(phonenumber) AS phonenumbers
FROM
(SELECT * FROM employee ORDER BY empname LIMIT 3 OFFSET 0) AS employee
LEFT OUTER JOIN phones ON employee.empid = phones.empid
GROUP BY employee.empid
But I get this error. ERROR: column "employee.empname" must appear in the GROUP BY clause or be used in an aggregate function
The only difference between two queries is that I am using sub query in the latter to limit the rows before joining. How do I solve this error?