INSERT with RETURNING clause in PostgreSQL

Introduction

The INSERT with RETURNING clause lets you add new data to a table and immediately get back the inserted rows or specific columns. This saves extra steps.

When you add a new user and want to get their unique ID right away.

When inserting a new order and need to know the order number generated by the database.

When you want to confirm what data was actually saved after an insert.

When you want to insert data and use the returned values in your program without another query.

Syntax

PostgreSQL

INSERT INTO table_name (column1, column2, ...) VALUES (value1, value2, ...) RETURNING column1, column2, ...;

You can return all columns by using RETURNING *.

RETURNING clause works only in PostgreSQL and some other databases, not all SQL databases support it.

Examples

Insert a new employee and get back the generated id.

PostgreSQL

INSERT INTO employees (name, age) VALUES ('Alice', 30) RETURNING id;

Insert a product and return all columns of the new row.

PostgreSQL

INSERT INTO products (name, price) VALUES ('Book', 12.99) RETURNING *;

Insert an order and return only order_id and total columns.

PostgreSQL

INSERT INTO orders (customer_id, total) VALUES (5, 100.50) RETURNING order_id, total;

Sample Program

This creates a users table with an auto-increment id. Then it inserts one user and returns the id and username of the inserted row.

PostgreSQL

CREATE TABLE users (id SERIAL PRIMARY KEY, username TEXT, email TEXT);

INSERT INTO users (username, email) VALUES ('john_doe', '[e-mail]') RETURNING id, username;

Important Notes

RETURNING helps avoid running a separate SELECT after INSERT.

If you insert multiple rows, RETURNING returns all inserted rows.

Make sure your client or tool supports reading the returned rows.

Summary

INSERT with RETURNING adds data and immediately returns specified columns.

It is useful to get auto-generated IDs or confirm inserted data.

Works well in PostgreSQL to simplify data workflows.

Practice

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

easy

A. It creates a backup of the inserted data.

B. It deletes rows after insertion.

C. It updates existing rows instead of inserting.

D. It returns specified columns of the newly inserted rows immediately.

Solution

1. Step 1: Understand the purpose of RETURNING

   The RETURNING clause in PostgreSQL is used to get back specified columns from the rows that were just inserted.

2. Step 2: Compare with other options

   The other options describe actions unrelated to RETURNING. RETURNING does not delete, update, or backup data.

3. Final Answer:

   It returns specified columns of the newly inserted rows immediately. -> Option D

4. Quick Check:

   RETURNING returns inserted data [OK]

Hint: RETURNING fetches inserted row data instantly [OK]

Common Mistakes:

• Thinking RETURNING deletes or updates data
• Confusing RETURNING with SELECT
• Assuming RETURNING creates backups

2. Which of the following is the correct syntax to insert a row and return the generated id in PostgreSQL?

easy

A. INSERT INTO users VALUES ('Alice') RETURNING id;

B. INSERT INTO users (name) RETURN id VALUES ('Alice');

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

D. INSERT INTO users (name) VALUES ('Alice') RETURN id;

Solution

1. Step 1: Check correct RETURNING syntax

   The correct syntax places RETURNING after VALUES and specifies the column to return, like RETURNING id.

2. Step 2: Validate each option

   INSERT INTO users (name) VALUES ('Alice') RETURNING id; matches the correct syntax. Placing RETURNING before VALUES or using RETURN instead of RETURNING is incorrect. INSERT INTO users VALUES ('Alice') RETURNING id; misses column list before VALUES.

3. Final Answer:

   INSERT INTO users (name) VALUES ('Alice') RETURNING id; -> Option C

4. Quick Check:

   RETURNING follows VALUES with column list [OK]

Hint: RETURNING goes right after VALUES clause [OK]

Common Mistakes:

• Placing RETURNING before VALUES
• Omitting column list in INSERT
• Using RETURN instead of RETURNING

3. Given the table products(id SERIAL PRIMARY KEY, name TEXT, price NUMERIC), what will this query return?

INSERT INTO products (name, price) VALUES ('Pen', 1.5) RETURNING id, price;

medium

A. The new product's id and price, e.g., (5, 1.5)

B. Only the id of the new product

C. An error because RETURNING can't return multiple columns

D. Nothing, INSERT does not return rows

Solution

1. Step 1: Understand RETURNING with multiple columns

   RETURNING can return one or more columns from the inserted row(s). Here, id and price are requested.

2. Step 2: Predict output

   The query inserts a new product and returns its auto-generated id and the price 1.5 as a row, e.g., (5, 1.5).

3. Final Answer:

   The new product's id and price, e.g., (5, 1.5) -> Option A

4. Quick Check:

   RETURNING multiple columns returns all requested [OK]

Hint: RETURNING can list multiple columns separated by commas [OK]

Common Mistakes:

• Assuming RETURNING returns only one column
• Expecting no output from INSERT
• Thinking RETURNING causes syntax error with multiple columns

4. What is wrong with this query?

INSERT INTO orders (product_id, quantity) VALUES (10, 3) RETURNING;

medium

A. VALUES clause is incorrectly formatted.

B. RETURNING clause is missing column names to return.

C. INSERT statement cannot have RETURNING clause.

D. product_id and quantity columns do not exist.

Solution

1. Step 1: Check RETURNING syntax

   RETURNING must specify at least one column or * to return. Here, it is empty, which is invalid syntax.

2. Step 2: Verify other parts

   VALUES clause and columns look correct. INSERT supports RETURNING. Assuming columns exist, no error there.

3. Final Answer:

   RETURNING clause is missing column names to return. -> Option B

4. Quick Check:

   RETURNING needs columns or * [OK]

Hint: RETURNING must specify columns or * [OK]

Common Mistakes:

• Leaving RETURNING empty
• Confusing RETURNING with WHERE
• Assuming RETURNING is optional but empty

5. You want to insert multiple rows into employees(name, department) and get back their generated id values. Which query correctly does this and returns all new ids?

hard

A. INSERT INTO employees (name, department) VALUES ('John', 'HR'), ('Jane', 'IT') RETURNING id;

B. INSERT INTO employees (name, department) RETURNING id VALUES ('John', 'HR'), ('Jane', 'IT');

C. INSERT INTO employees (name, department) VALUES ('John', 'HR'); RETURNING id; INSERT INTO employees (name, department) VALUES ('Jane', 'IT'); RETURNING id;

D. INSERT INTO employees (name, department) VALUES ('John', 'HR'), ('Jane', 'IT') RETURN id;

Solution

1. Step 1: Understand multi-row INSERT with RETURNING

   PostgreSQL allows inserting multiple rows in one statement and RETURNING returns all inserted rows' specified columns.

2. Step 2: Analyze each option

   INSERT INTO employees (name, department) VALUES ('John', 'HR'), ('Jane', 'IT') RETURNING id; correctly inserts two rows and returns their ids. INSERT INTO employees (name, department) RETURNING id VALUES ('John', 'HR'), ('Jane', 'IT'); misplaces RETURNING before VALUES. INSERT INTO employees (name, department) VALUES ('John', 'HR'); RETURNING id; INSERT INTO employees (name, department) VALUES ('Jane', 'IT'); RETURNING id; splits inserts and RETURNING incorrectly. INSERT INTO employees (name, department) VALUES ('John', 'HR'), ('Jane', 'IT') RETURN id; uses invalid RETURN keyword.

3. Final Answer:

   INSERT INTO employees (name, department) VALUES ('John', 'HR'), ('Jane', 'IT') RETURNING id; -> Option A

4. Quick Check:

   Multi-row INSERT with RETURNING returns all rows [OK]

Hint: Use RETURNING after multi-row VALUES to get all ids [OK]

Common Mistakes:

• Placing RETURNING before VALUES
• Splitting inserts instead of multi-row insert
• Using RETURN instead of RETURNING