INSERT with RETURNING clause in PostgreSQL - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to insert a new user and return the inserted id.

PostgreSQL

INSERT INTO users (name, email) VALUES ('Alice', '[e-mail]') [1] id;

Drag options to blanks, or click blank then click option'

AOUTPUT

BSELECT

CRETURNING

DFETCH

Attempts:

3 left

💡 Hint

Common Mistakes

Using SELECT instead of RETURNING after INSERT.

Forgetting to specify the column after RETURNING.

The RETURNING clause in PostgreSQL allows you to get the inserted row's columns immediately after an INSERT.

2fill in blank

medium

Complete the code to insert a product and return both id and name.

PostgreSQL

INSERT INTO products (name, price) VALUES ('Book', 9.99) [1] id, name;

Drag options to blanks, or click blank then click option'

ARETURNING

BFETCH

CSELECT

DOUTPUT

Attempts:

3 left

💡 Hint

Common Mistakes

Using OUTPUT which is not valid in PostgreSQL.

Trying to use SELECT after INSERT.

Use RETURNING to get multiple columns from the inserted row.

3fill in blank

hard

Fix the error in the code to return the inserted row's email.

PostgreSQL

INSERT INTO customers (name, email) VALUES ('Bob', '[e-mail]') [1] email;

Drag options to blanks, or click blank then click option'

AFETCH

BRETURNING

COUTPUT

DSELECT

Attempts:

3 left

💡 Hint

Common Mistakes

Using SELECT instead of RETURNING.

Using OUTPUT which is for other SQL dialects.

The correct keyword to return inserted columns in PostgreSQL is RETURNING.

4fill in blank

hard

Fill both blanks to insert a new order and return order_id and total.

PostgreSQL

INSERT INTO orders (customer_id, total) VALUES (123, 45.67) [1] [2];

Drag options to blanks, or click blank then click option'

ARETURNING

BSELECT

Corder_id, total

DOUTPUT

Attempts:

3 left

💡 Hint

Common Mistakes

Using OUTPUT which is not valid in PostgreSQL.

Putting SELECT instead of RETURNING.

Use RETURNING followed by the columns you want to get back, separated by commas.

5fill in blank

hard

Fill all three blanks to insert a new employee and return id and name.

PostgreSQL

INSERT INTO employees (name, department, salary) VALUES ('Eve', 'HR', 60000) [1] [2] [3];

Drag options to blanks, or click blank then click option'

ARETURNING

Bname

Cdepartment

Did,

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting commas between column names.

Using OUTPUT instead of RETURNING.

The RETURNING clause is followed by the columns you want to get back. Separate columns with commas. Here, id, name are returned (note the commas).

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