Inner Join VS Outer Join 看图就行 有更新!

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Let's consider a common scenario of two tables: product prices and quantities. The common information in the two tables is product name, so that is the logical column to join the tables on. There are some products that are common in the two tables; others are unique to one of the tables and don't have a match in the other table.

An inner join on Products returns information about only those products that are common in both tables.