SQL Join on Multiple Columns 101: The Easy Way vs The Hard Way

By Laurent Maurer · October 26, 2022 · 4 min read

Difficulty Level: Expert

In this article, we will discuss how to use SQL Join on multiple columns.

This function is a built-in operation used for working on several tables.

Let’s dive into how to use it in both Code & No Code.

Summary

SQL Join on Multiple Columns: The Easy Way Without Coding

1. Dataset

Let’s take a look at the following MongoDB Sample Datasets (Use our Public Sample Datasets for free).

2. Syntax:

Step 1: Search and drag and drop the Join function in the sidebar:

Step 2: Select in the dropdown list, the Join type you want to operate:

Step 3: Click on the “+” button as many times as required to join on multiple columns (in the example below, we have a pair of matching columns):

3. Example:

Input:

Output:

SQL Join on Multiple Columns: The Hard Way With Code

To reproduce the same output as above but with code, you need to write the following query:

Input:

				
					SELECT account_id, account_id,
       transactions_symbol, products
FROM accounts
INNER JOIN transactions
ON account_id.accounts =account_id.transactions
AND  transactions_symbol.transactions = products.accounts

The more you want to join on multiple columns the longer your SQL query will be. Your SQL query won’t be optimized this way and less and less readable for any data practitioner.

Conclusion

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