Outer Join

What Does Outer Join Mean?

An outer join in SQL is a specific kind of query construction that deliberately allows for a wider array of results. The process of building specific queries in SQL to get database results is a highly technical one, and an outer join is an example of a type of detail learned and utilized by database researchers.


Techopedia Explains Outer Join

Someone who is writing a query can use a left or right outer join to include table results that only have a given component, rather than requiring multiple components to be present. A left outer join includes all rows in a table regardless of whether a specifically positioned column has results or not. By contrast, an inner join requires both components to be present.

Because outer joins provide for more diversity, they are often useful in searches that are less rigid and do not require strict adherence to the principle of having consistent data from multiple search components.


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Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.