Sqlite inner join on no match8/15/2023 If you are not sure how the DELETE statement works, the linked tutorial may well shed some light on the subject.ĭuplicate values inflate our output with repeating records and do not contribute to the results we obtain meaningfully. We can achieve that by writing the following code: DELETE FROM dept_manager_dup First, let’s remove the duplicates from the two tables. So, if you’ve read the tutorial on the duplicate records, there are a few things we want to delete. To clarify the concept, let’s look at an application. In SQL terms, this translates to retrieving all matching values of the two tables plus all values from the left table that do not match any values from the right table. That’s why, compared to the INNER JOIN, the result set, coloured in red, includes the rest of the area of the left table. Its output allows us to see all records from the table on the left side of the JOIN, including all matching rows of the two tables. The Venn diagram you see in the picture below, allows you to visualize how a LEFT JOIN in SQL works. Side note: If you don’t have the ‘ employees’ database, you can download it here. You can learn all this and more in our SQL course. Moreover, we will be handling duplicate records, so make sure you know a thing or two about it. If you have any idea what JOINS are and you are familiar with the INNER JOIN type, learning how to use the LEFT JOIN in SQL should be a walk in the park. Martin Ganchev 12 min read How does a LEFT JOIN in SQL work?
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