Summary: JOIN Statements总结：连接语句

Congratulations! You have completed this lesson. At this point in the course, you know:
恭喜！您已完成本课程。此时，您已经知道：

• A join combines the rows from two or more tables based on a relationship between certain columns in these tables.
  一个连接基于这些表中某些列之间的关系，将两个或多个表的行组合在一起。
• To combine data from three or more different tables, you simply add new joins to the SQL statement.
  要组合来自三个或更多不同表的数据，您只需在 SQL 语句中添加新的连接。
• There are two types of joins: inner join and outer join; and three types of outer joins: left outer join, right outer join, and full outer join.
  连接有两种类型：内连接和外连接；外连接有三种类型：左外连接、右外连接和全外连接。
• The most common type of join is the inner join, which matches the results from two tables and returns the selected elements from each table, only where corresponding elements in both the tables are the same.
  最常见的连接类型是内连接，它匹配两个表的结果，并返回每个表中被选择的元素，仅当两个表中对应的元素相同时。
• You can use an alias as shorthand for a table or column name.
  您可以使用别名作为表名或列名的一种简写。