How Can I Combine Data from Two MySQL Tables (services and clients) Using a LEFT JOIN?

Combining MySQL Data with LEFT JOIN

MySQL's LEFT JOIN is a crucial tool for merging data from multiple tables, facilitating insightful data extraction and report generation. This guide illustrates using a LEFT JOIN to combine data from services and clients tables.

Scenario: Services and Clients Tables

Imagine you have two tables: services (with columns id, client, service) and clients (with columns id, name, email). The objective is to generate a combined list of services, including the associated client names.

Employing LEFT JOIN

A LEFT JOIN ensures all rows from the left table (here, services) are included in the result set. Matching rows from the right table (clients) are joined based on a common column (in this instance, client in services and id in clients).

The following query accomplishes this:

<code class="language-sql">SELECT *
FROM services AS s
LEFT JOIN clients AS c
ON s.client = c.id;</code>

This query uses SELECT * to retrieve all columns from both tables. The LEFT JOIN links the client column of the services table to the id column of the clients table.

Interpreting the Results

The outcome is a new table encompassing all columns from both services and clients. For each services entry, the corresponding client name is displayed if a matching client ID exists. Importantly, services rows lacking a match in clients are still included; however, the client name fields will show as NULL.

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