12/19/2023 0 Comments Multi left outer join in razorsql![]() The second table is employees, and you can create it using this query. You can get the query for creating the table here. The first table, departments, has the following data: id 4 Examples of LEFT OUTER JOIN The Dataset for Examples 1-3 Now that you know the syntax, the only thing left is to put it into practice. When the tables are joined, it goes without saying that you can choose any column from both tables in SELECT. You can see a visual example of this in our article on how the LEFT JOIN works. When no such values are in the right table, the returned values will be NULL. second table, or table_2) table where the joining condition is matched. The LEFT JOIN will return only values from the right (i.e. Then the query will look at the joining condition – in this case, where a value in column from table_2 matches a value from column from table_1. Why? Because this is the nature of LEFT JOIN – it returns all the rows from the left (i.e. It will first return all the rows from table_1, no matter the joining condition. So how does LEFT OUTER JOIN work? In the generic example above, the query will reference table_1 and left join it with table_2. Use the ON keyword to specify the joining condition.Use the LEFT JOIN keyword to reference the second table.The syntax of LEFT JOIN follows the standard JOIN syntax: The ‘Outer’ is implied, as there’s no other left join than a left outer join. When you see it, it simply means LEFT OUTER JOIN. ![]() This is because SQL accepts both LEFT OUTER JOIN and LEFT JOIN.Īs LEFT JOIN is shorter, it is used more often. You’ve probably seen SQL code examples where the tables are joined only with LEFT JOIN. Long answer: The full name of this type of join really is LEFT OUTER JOIN. What’s the Difference Between LEFT OUTER JOIN And LEFT JOIN? These types of JOINs are called outer joins.Ī LEFT JOIN is a type of outer join that outputs all rows from the left table and the matching rows from the right table. There are other JOIN types that can return rows from a joined table even if the row has no matching row in the other table. It’s a join type that returns only the matching rows from both joined tables. If you need a refresher on some concepts as we go along, remember our SQL JOIN Cheat Sheet. Let’s introduce LEFT OUTER JOIN then we’ll make it more interesting with practical examples. You’ll complete over 90 hands-on exercises – all based on real-world examples! Aside from the basics, it explains joining multiple tables and using self- and non-equi joins. To get a comprehensive recap of different types of JOINs, try our interactive SQL JOINs course. ![]()
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