Functions returning SETOF in PostgreSQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does a PostgreSQL function returning SETOF mean?

It means the function returns a set of rows, like a table, instead of a single value. You get multiple rows as output.

beginner

How do you define the return type of a function that returns multiple rows in PostgreSQL?

You use RETURNS SETOF <table_name> or RETURNS SETOF <type> to specify the function returns multiple rows of that table or type.

intermediate

What SQL command inside a SETOF function returns multiple rows?

You use RETURN QUERY followed by a SELECT statement to return multiple rows from the function.

beginner

Can a function returning SETOF be used like a table in a SELECT statement?

Yes! You can use the function in the FROM clause like a table to get its rows as query results.

intermediate

Why use functions returning SETOF instead of views?

Functions returning SETOF can accept parameters and have logic, so they are more flexible than views which are fixed queries.

What keyword specifies a function returns multiple rows in PostgreSQL?

A ARRAY

B TABLE

C SETOF

D MULTIROW

The keyword SETOF tells PostgreSQL the function returns a set of rows.

Which SQL statement inside a function returns multiple rows?

A RETURN QUERY SELECT ...

B RETURN NEXT

C RETURN SINGLE

D RETURN ROW

RETURN QUERY followed by a SELECT returns multiple rows from the function.

How do you call a function returning SETOF in a query?

A In the WHERE clause

B In the FROM clause like a table

C In the SELECT list only

D You cannot call it in queries

Functions returning SETOF are used in the FROM clause to get their rows.

What is a benefit of functions returning SETOF over views?

A They cannot be used in SELECT

B They are faster

C They return only one row

D They can accept parameters

Functions returning SETOF can accept parameters, unlike views.

Which of these is a valid return type for a SETOF function?

A SETOF tablename

B SETOF INTEGER[]

C SETOF BOOLEAN

D SETOF VOID

SETOF followed by a table name or composite type is valid to return multiple rows.

Explain how to create and use a PostgreSQL function that returns multiple rows using SETOF.

Think about how the function acts like a table returning many rows.

Describe the advantages of using functions returning SETOF compared to views in PostgreSQL.

Consider flexibility and customization.