INSERT with RETURNING clause in PostgreSQL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the RETURNING clause do in a PostgreSQL INSERT statement?

The RETURNING clause returns specified columns from the newly inserted row(s) immediately after the INSERT operation, allowing you to see the inserted data without running a separate query.

beginner

Write a simple INSERT statement with a RETURNING clause to insert a new user with name 'Alice' and return the generated user ID.

Example:<br>INSERT INTO users (name) VALUES ('Alice') RETURNING id;<br>This inserts a new user named Alice and returns the new user's ID.

intermediate

Can the RETURNING clause return multiple columns? If yes, how?

Yes, you can return multiple columns by listing them separated by commas. For example:<br>RETURNING id, name, created_at;<br>This returns the ID, name, and creation timestamp of the inserted row.

intermediate

Why is using RETURNING better than running a separate SELECT after an INSERT?

Using RETURNING is faster and safer because it gets the inserted data in one step. It avoids race conditions where the data might change between the INSERT and a separate SELECT.

beginner

What happens if you use RETURNING * in an INSERT statement?

The RETURNING * clause returns all columns of the newly inserted row(s). This is useful when you want to see every detail of the inserted data without listing columns individually.

What does the RETURNING clause do in a PostgreSQL INSERT statement?

A Deletes rows after insertion

B Creates a new table

C Updates existing rows

D Returns specified columns from the inserted row(s)

The RETURNING clause returns specified columns from the newly inserted rows.

Which of the following is a valid use of RETURNING in an INSERT?

A INSERT INTO users (name) VALUES ('Bob') WHERE id = 1;

B INSERT INTO users (name) VALUES ('Bob') RETURNING id;

C INSERT INTO users (name) RETURNING id VALUES ('Bob');

D INSERT RETURNING id INTO users VALUES ('Bob');

Option B correctly uses RETURNING after the VALUES clause.

Can RETURNING return multiple columns?

A Yes, by listing columns separated by commas

B No, only one column is allowed

C Only if the table has one column

D Only with <code>SELECT</code> statements

You can return multiple columns by listing them separated by commas in the RETURNING clause.

What is a benefit of using RETURNING instead of a separate SELECT after INSERT?

A It locks the entire table

B It deletes the inserted row automatically

C It avoids race conditions and is more efficient

D It requires more queries

Using RETURNING avoids race conditions and reduces the number of queries.

What does RETURNING * do?

A Returns all columns of the inserted row(s)

B Returns no columns

C Returns only the first column

D Returns the table schema

RETURNING * returns all columns of the inserted row(s).

Explain how the RETURNING clause works in a PostgreSQL INSERT statement and why it is useful.

Think about how you get data back immediately after inserting.

Write an example of an INSERT statement using RETURNING to get the new row's ID and name.

Use a simple table like users with columns id and name.