In SQL, the LEFT JOIN clause is used to retrieve data from multiple tables based on a related column between them. This type of join returns all records from the left table and the matched records from the right table.

Here’s an example to illustrate the usage of LEFT JOIN:

SELECT column_name(s)
FROM table1
LEFT JOIN table2 ON table1.column_name = table2.column_name;

In this example, table1 is the left table, and table2 is the right table. The LEFT JOIN returns all the records from table1 and the matching records from table2 based on the specified condition.

It’s important to understand that if there are no matching records in table2 for a particular record in table1, the query will still return the record from table1, with NULL values for the columns from table2.

In summary, the LEFT JOIN in SQL is a powerful feature for retrieving data from multiple tables, especially when you want to include all records from the left table regardless of whether there are matching records in the right table.

For more information, you can refer to the official documentation of the specific SQL database you are using, whether it’s MySQL, PostgreSQL, SQL Server, or other databases.

Now that you’ve learned the basics of LEFT JOIN in SQL, you can start leveraging the power of this powerful feature to write more complex and efficient queries for your database operations.