Manipulate data in PostgreSQL

On the previous step, you have connected to PostgreSQL as the superuser postgres. Now, let’s insert some sample data and operate with it in PostgreSQL.

Create a database

Let’s create the database test. Use the CREATE DATABASE command:

CREATE DATABASE test;

Create a table

Let’s create a sample table Customers in the test database using the following command:

CREATE TABLE customers (
    id SERIAL PRIMARY KEY,  -- 'id' is an auto-incrementing integer
    first_name VARCHAR(50), -- 'first_name' is a string with a maximum length of 50 characters
    last_name VARCHAR(50),  -- 'last_name' is a string with a maximum length of 50 characters
    email VARCHAR(100)      -- 'email' is a string with a maximum length of 100 characters
);

Hint:Having issues with table creation? Check our Troubleshooting guide

Insert the data

Populate the table with the sample data as follows:

INSERT INTO customers (first_name, last_name, email)
VALUES 
    ('John', 'Doe', 'john.doe@example.com'),  -- Insert a new row
    ('Jane', 'Doe', 'jane.doe@example.com');
    ('Alice', 'Smith', 'alice.smith@example.com');

Query data

Let’s verify the data insertion by querying it:

SELECT * FROM customers;

Expected output

id | first_name | last_name |          email
----+------------+-----------+-------------------------
  1 | John       | Doe       | john.doe@example.com
  2 | Jane       | Doe       | jane.doe@example.com
  3 | Alice      | Smith     | alice.smith@example.com
(3 rows)

Update data

Let’s update John Doe’s record with a new email address.

1. Use the UPDATE command for that:

   UPDATE customers 
   SET email = 'john.doe@myemail.com'
   WHERE first_name = 'John' AND last_name = 'Doe';
   

2. Query the table to verify the updated data:

   SELECT * FROM customers WHERE first_name = 'John' AND last_name = 'Doe';
   

   Expected output

    id | first_name | last_name |          email
   ----+------------+-----------+-------------------------
     2 | Jane       | Doe       | jane.doe@example.com
     3 | Alice      | Smith     | alice.smith@example.com
     1 | John       | Doe       | john.doe@myemail.com
   (3 rows)
   

Delete data

Use the DELETE command to delete rows. For example, delete the record of Alice Smith:

DELETE FROM Customers WHERE first_name = 'Alice' AND last_name = 'Smith';

If you wish to delete the whole table, use the DROP TABLE command instead as follows:

DROP TABLE customers;

To delete the whole database, use the DROP DATABASE command:

DROP DATABASE test;

Congratulations! You have used basic create, read, update and delete (CRUD) operations to manipulate data in Percona Distribution for PostgreSQL. To deepen your knowledge, see the data manipulation section in PostgreSQL documentation.

Next steps

What’s next?

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