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Asked: 2024-09-22T12:12:28+05:30 In:

What is the difference between a left join and a left outer join in SQL Server, and do they produce the same results?

Hey everyone! I was diving into SQL Server recently and came across a bit of a conundrum. I’m trying to understand the difference between a **LEFT JOIN** and a **LEFT OUTER JOIN**. I’ve heard that they might produce the same results, but I’m not entirely convinced.

Could anyone explain if there’s a real difference between the two? Do they behave differently in certain situations, or can I use them interchangeably without worrying about the outcome? Would love to hear your thoughts or experiences! Thanks!

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    2 Answers


    1. In SQL Server, the terms **LEFT JOIN** and **LEFT OUTER JOIN** are used interchangeably. They both refer to the same type of join operation that retrieves all records from the left table and the matched records from the right table. If there are no matches, NULL values are returned for the columns of the right table. The inclusion of the word “OUTER” is optional, and many developers prefer to use **LEFT JOIN** for brevity. Nonetheless, it is essential to understand that both will produce the same result set, so you can confidently use either syntax based on your programming preference or coding standards in your projects.

      However, clarity in your SQL queries can enhance readability, especially for those who may be new to SQL or reviewing your code. Using **LEFT OUTER JOIN** can make it explicit that you are performing an outer join, which is beneficial in more complex queries involving multiple joins. In summary, while both terms yield the same outcomes in SQL Server, opting for one over the other can depend more on your audience and coding style rather than any functional difference in behavior.



    2. Hi there!

      Welcome to the world of SQL Server! It’s great that you’re diving into this topic. The difference between LEFT JOIN and LEFT OUTER JOIN can be a bit confusing at first, but don’t worry, I got you covered!

      In short, there is actually no difference between the two. They both produce the same results.

      When you use LEFT JOIN, it is just a shorthand for LEFT OUTER JOIN. The word “OUTER” is optional in this case.

      So, you can use either in your queries, and they’ll behave the same way. Both will return all the records from the left table (the first table in your join), and matched records from the right table (the second table). If there are no matches in the right table, you’ll just see NULL values in those columns.

      It’s always good to be aware of these terms, but in practice, you can use them interchangeably. Just keep an eye on your syntax and you’ll be fine!

      If you have more questions, feel free to ask. Happy coding!


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