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YSQL Tutorial: Fundamentals
In this tutorial you’ll learn how to use YugaByte DB’s PostgreSQL-compatible YSQL interface to query data from the Northwind sample database using SELECT, FROM, ORDER BY, LIMIT and other basic clauses and operators. For detailed information concerning specific clauses or operators, please refer to the official PostgreSQL documentation.
To start, make sure you have all the necessary prerequisites and have logged into the YSQL shell.fetch
Note: These instructions last tested with YugaByte DB 1.3
Let's begin!
SELECT data from one column
In this exercise we will select all the data in the company_names column from the customers table.
select company_name from customers;
The query should return 91 rows.
SELECT data from multiple columns
In this exercise we will select all the data in three columns from the employees table.
select employee_id,first_name,last_name,birth_date from employees;
The query should return 9 rows.
SELECT data from all the columns and rows in a table
In this exercise we will select all the data, from all columns in the order_details table.
select * from order_details;
The query should return 2155 rows.
SELECT with an expression
In this exercise we will combine the first_name and last_name columns to give us full names, along with their titles from the employees table.
select first_name || '' || last_name as full_name,title from employees;
The query should return 9 rows.
SELECT with an expression, but without a FROM clause
In this exercise we will use an expression, but omit specifying a table because it doesn't require one.
SELECT 5 * 3 AS result;
The query should return 1 row with a result of 15.
SELECT with a column alias
In this exercise we will use the alias title for the contact_title column and output all the rows.
SELECT contact_title AS title FROM customers;
The query should return 91 rows.
SELECT with a table alias
In this exercise we will use the alias details for the order_details table and output all the rows.
SELECT product_id, discount FROM order_details AS details;
The query should return 2155 rows.
SELECT with an ascending ORDER BY
In this exercise we sort employees by first_name in ascending order.
SELECT first_name,
last_name,
title,
address,
city
FROM employees
ORDER BY first_name ASC;
The query should return 9 rows.
SELECT with an descending ORDER BY
In this exercise we sort employees by first_name in descending order.
SELECT first_name,
last_name,
title,
address,
city
FROM employees
ORDER BY first_name DESC;
The query should return 9 rows.
SELECT with a ascending and descending ORDER BYs
In this exercise we sort employees by first_name in ascending order and then by last name in descending order.
SELECT first_name,
last_name
FROM employees
ORDER BY first_name ASC,
last_name DESC;
The query should return 9 rows
SELECT with DISTINCT on one column
In this exercise we query the orders table and return only the distinct values in the order_id column.
SELECT DISTINCT order_id
FROM orders;
The query should return 830 rows
SELECT with DISTINCT including multiple columns
In this exercise we query the orders table and return only the distinct values based on combining the specified columns.
SELECT DISTINCT order_id,
customer_id,
employee_id
FROM orders;
The query should return 830 rows
SELECT with DISTINCT ON expression
In this exercise we query the orders table and ask to keep just the first row of each group of duplicates.
SELECT DISTINCT ON (employee_id)employee_id AS id_number,
customer_id
FROM orders
ORDER BY id_number,
customer_id;
The query should return 9 rows
WHERE clause with an equal = operator
In this exercise we'll query the orders table and return just the rows that equal the employee_id of 8.
SELECT order_id,
customer_id,
employee_id,
order_date
FROM orders
WHERE employee_id=8;
This query should return 104 rows.
WHERE clause with an AND operator
In this exercise we'll query the orders table and return just the rows that have an employee_id of 8 and a customer_id equal to "FOLKO".
SELECT order_id,
customer_id,
employee_id,
order_date
FROM orders
WHERE employee_id=8
AND customer_id= 'FOLKO';
This query should return 6 rows.
WHERE clause with an OR operator
In this exercise we'll query the orders table and return just the rows that have an employee_id of 2 or 1.
SELECT order_id,
customer_id,
employee_id,
order_date
FROM orders
WHERE employee_id=2
OR employee_id=1;
This query should return 219 rows.
WHERE clause with an IN operator
In this exercise we'll query the order_ details table and return just the rows with an order_id of 10360 or 10368.
SELECT *
FROM order_details
WHERE order_id IN (10360,
10368);
This query should return 9 rows.
WHERE clause with a LIKE operator
In this exercise we'll query the customers table and return just the rows that have a company_name that starts with the letter "F".
SELECT customer_id,
company_name,
contact_name,
city
FROM customers
WHERE company_name LIKE 'F%';
This query should return 8 rows.
WHERE clause with a BETWEEN operator
In this exercise we'll query the orders table and return just the rows that have an order_id between 10,985 and 11,000.
SELECT order_id,
customer_id,
employee_id,
order_date,
ship_postal_code
FROM orders
WHERE order_id BETWEEN 10985 AND 11000;
This query should return 16 rows.
WHERE clause with a not equal <> operator
In this exercise we'll query the employees table and return just the rows where the employee_id is not eqal to "1".
SELECT first_name,
last_name,
title,
address,
employee_id
FROM employees
WHERE employee_id <> 1;
This query should return 8 rows.
SELECT with a LIMIT clause
In this exercise we'll query the products table and return just the first 12 rows.
SELECT product_id,
product_name,
unit_price
FROM products
LIMIT 12;
This query should return 12 rows.
SELECT with LIMIT and OFFSET clauses
In this exercise we'll query the products table and skip the first 4 rows before selecting the next 12.
SELECT product_id,
product_name,
unit_price
FROM products
LIMIT 12
OFFSET 4;
This query should return 12 rows.
SELECT with LIMIT and ORDER BY clauses
In this exercise we'll query the products table, order the results in a descending order by product_id and limit the rows returned to 12.
SELECT product_id,
product_name,
unit_price
FROM products
ORDER BY product_id DESC
LIMIT 12;
This query should return 12 rows.
SELECT with FETCH and ORDER BY clauses
In this exercise we'll query the customers table and order the results by company_name in ascending order, while limiting the rows returned to 7.
SELECT customer_id,
company_name,
contact_name,
contact_title
FROM customers
ORDER BY company_name ASC FETCH NEXT 7 ROWS ONLY;
This query should return 7 rows.
SELECT with FETCH, OFFSET and ORDER BY clauses
In this exercise we'll query the customers table and order the results by company_name in ascending order, while limiting the rows returned to the 7 that come after the first 2.
SELECT customer_id,
company_name,
contact_name,
contact_title
FROM customers
ORDER BY company_name ASC
OFFSET 2 FETCH NEXT 7 ROWS ONLY;
This query should return 7 rows.
SELECT with an IN clauses
In this exercise we will query the shippers table and return only the rows that have a shipper_id of 1, 2, 3 or 4.
SELECT *
FROM shippers
WHERE shipper_id IN (1,2,3,4);
This query should return 4 rows
SELECT with a NOT IN clause
In this exercise we will query the shippers table and return all the rows, except those that have a shipper_id of 3 or 4.
SELECT *
FROM shippers
WHERE shipper_id NOT IN (3,4);
This query should return 4 rows
SELECT with an IN clause in a subquery
SELECT
customer_id
FROM
orders
WHERE
CAST (order_date AS DATE) = '1998-05-06';
Results
SELECT with BETWEEN
SELECT product_id,
product_name,
quantity_per_unit
FROM products
WHERE product_id BETWEEN 10 AND 20
This query should return 11 rows
SELECT with NOT BETWEEN
SELECT product_id,
product_name,
quantity_per_unit
FROM products
WHERE product_id NOT BETWEEN 10 AND 20
This query should return 66 rows
SELECT with a LIKE operator
SELECT product_id,
product_name,
quantity_per_unit
FROM products
WHERE product_name LIKE '%C%'
This query should return 17 rows
SELECT with a LIKE operator using % and _
SELECT product_id,
product_name,
quantity_per_unit
FROM products
WHERE product_name LIKE '_e%'
This query should return 5 rows
SELECT with a NOT LIKE operator
SELECT product_id,
product_name,
quantity_per_unit
FROM products
WHERE product_name NOT LIKE 'C%'
This query should return 68 rows
SELECT with an ILIKE operator
SELECT product_id,
product_name,
quantity_per_unit
FROM products
WHERE product_name ILIKE '%C%'
This query should return 37 rows
SELECT with a IS NULL operator
Query
Results
SELECT with a IS NOT NULL operator
Query
Results
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