An outer join returns a set of records or rows that include what an inner join would return but also includes other rows for which no corresponding match is found in the other table. Each of these outer joins refers to the part of the data that is being compared, combined, and returned. Sometimes nulls will be produced in this process as some data is shared while other data is not. A left outer join will return all the data in Table 1 and all the shared data so, the inner part of the Venn diagram example , but only corresponding data from Table 2, which is the right join.
In our example database, there are two products — oranges and tomatoes — on the 'left' Prices table that do not have a corresponding entry on the 'right' Quantities table. The other rows in the result are the same as the inner join. A right outer join returns Table 2's data and all the shared data, but only corresponding data from Table 1, which is the left join. Similar to the left join example, the output of a right outer join includes all rows of the inner join and two rows — broccoli and squash — from the 'right' Quantities table that do not have matching entries on the left.
A full outer join, or full join, which is not supported by the popular MySQL database management system, combines and returns all data from two or more tables, regardless of whether there is shared information.
When you use an inner join there is no difference between the on and where clauses. Both produce the same result as in the following:.
They produce different results as in the following:. You can see in the result, the first one returns all records from the left table and disregards the extra condition. Next Recommended Reading. Windows 10 Vs Windows Introduction In this article, I am going to explain what is the difference between Inner join and Left join with examples.
This is one of the very common SQL server interview questions. In general, tables are related to each other using foreign key constraints. Now, first we will create a Database and two tables to apply the joins for understanding.
Create database chittadb Now, select the script query then press F5 or click on Execute button to execute the above script. OR select emp. Name ,emp. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more.
Ask Question. Asked 11 years, 6 months ago. Active 2 years, 8 months ago. Viewed 70k times. Improve this question. This question has the better title of the two. Add a comment. Active Oldest Votes. The ON clause defines the relationship between the tables. If the ON clause fails you still get a row with columns from the left table but with nulls in the columns from the right table. Improve this answer.
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