In this section, we will cover how to insert data into PostgreSQL tables. This is a fundamental operation that allows you to populate your database with information. We will explore the INSERT statement, various ways to insert data, and practical examples to solidify your understanding.

1. INSERT Statement: The basic SQL command used to add new rows to a table.
2. Single Row Insertion: Inserting one row at a time.
3. Multiple Row Insertion: Inserting multiple rows in a single statement.
4. Returning Clause: Retrieving values from the inserted rows.

The INSERT statement is used to add new rows to a table. The basic syntax is as follows:

Let's assume we have a table named employees with the following structure:

To insert a single row into the employees table, you would use the following INSERT statement:

You can insert multiple rows in a single INSERT statement by separating each row's values with a comma:

The RETURNING clause allows you to retrieve values from the inserted rows. This is particularly useful when you need to get the generated primary key or other computed values.

This statement will insert a new row and return the id, first_name, and last_name of the inserted row.

1. Create a table named products with the following structure:

   CREATE TABLE products (
       product_id SERIAL PRIMARY KEY,
       product_name VARCHAR(100),
       price NUMERIC(10, 2),
       created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
   );
   

2. Insert a single row into the products table with the following values:

   • product_name: 'Laptop'
   • price: 999.99

Solution:

1. Insert the following rows into the products table:
   • product_name: 'Smartphone', price: 499.99
   • product_name: 'Tablet', price: 299.99
   • product_name: 'Smartwatch', price: 199.99

Solution:

1. Insert a new row into the products table with the following values:

   • product_name: 'Headphones'
   • price: 149.99

2. Use the RETURNING clause to retrieve the product_id and product_name of the inserted row.

Solution:

• Missing Columns: Ensure that the columns specified in the INSERT statement match the values provided.
• Data Types: Verify that the values being inserted match the data types of the columns.
• Default Values: Utilize default values for columns when appropriate to simplify your INSERT statements.

In this section, we covered the basics of inserting data into PostgreSQL tables using the INSERT statement. We explored single and multiple row insertions, as well as the RETURNING clause. By practicing the provided exercises, you should now be comfortable with adding data to your PostgreSQL tables. In the next section, we will delve into querying data, which will allow you to retrieve and manipulate the data you've inserted.