In this post, we will understand the difference between left outer join, right outer join, and full outer join.
Left Outer Join
It fetches all the rows from the table on the left.
It is same as ‘Inner Join + all the unmatched rows from the left table’.
The data that isn’t matched on the right table is lost.
Example:
SELECT [column_1, column_2, ….] FROM table_1 LEFT OUTER JOIN table_2 ON table_1.matching_column = table_2.matching_column
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Right Outer Join
It fetches all the rows of the table on the right.
It is similar to performing ‘Inner Join + all of the unmatched rows from the right table’.
The unmatched data from the left table is lost.
Example:
SELECT [column_1, column_2, ….] FROM table_1 RIGHT OUTER JOIN table_2 ON table_1.matching_column = table_2.matching_column
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全外連接
它從兩個表中獲取所有的行。
它類似于執行“內連接 + 左表中所有不匹配的行 + 右表中所有不匹配的行”。
在此操作中不會丟失任何數據。
示例：
SELECT [column_1, column_2, ….] FROM table_1 FULL OUTER JOIN table_2 ON table_1.matching_column = table_2.matching_column
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以上就是左、右和完全外連接之間的區別的詳細內容，更多請關注www.92cms.cn其它相關文章！
