Joining Tables (learnsqlonline.org)

Table joins allow us to combine data from two or more tables based on a shared column or key. By leveraging table joins, we can create logical connections between tables, enabling us to fetch and analyze data from multiple sources simultaneously. This functionality is vital in performing complex queries and extracting valuable insights from relational databases.

#Joining Tables
CREATE TABLE customers (
    id INTEGER PRIMARY KEY,
    first_name TEXT,
    last_name TEXT
);

CREATE TABLE orders (
    id INTEGER PRIMARY KEY,
    customer_id INTEGER,
    product_name TEXT
);

SQL provides various types of table joins, including inner join, left join, right join, and full join. Inner join returns only the matched records from both tables, while left join and right join include all records from one table and matched records from the other. Full join combines all records from both tables, including unmatched ones.

Joining Tables Exercise Solution

#Code Completed
INSERT INTO customers (first_name, last_name) VALUES
    ("John", "Doe");

INSERT INTO orders (customer_id, product_name) VALUES
    (last_insert_rowid(), "Coke"),
    (last_insert_rowid(), "Sprite");

.mode column
.headers on
SELECT product_name, first_name, last_name
FROM orders
JOIN customers ON orders.customer_id = customers.id;

Table joins are a fundamental operation in SQL, allowing us to unify data from multiple tables for comprehensive analysis. By understanding the types of joins available and their applications, we can leverage this powerful functionality to extract valuable insights from complex relational databases.