左连接和左外连接有什么区别？ [重复]

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• LEFT JOIN vs. LEFT OUTER JOIN in SQL Server 17 answers

SQL Server 17答案中的LEFT JOIN与LEFT OUTER JOIN

I have created 2 tables as

我创建了2个表

CREATE TABLE table1(customerName VARCHAR(20),custid NUMBER ,order_id NUMBER ,price NUMBER );
CREATE TABLE table2(id NUMBER ,salary NUMBER );

Now, I tried to use the queries

现在,我尝试使用查询

SELECT t1.customername,t1.custid,t2.salary FROM table1 t1 left join table2 t2 ON t1.custid = t2.id;
SELECT t1.customername,t1.custid,t2.salary FROM table1 t1 left outer join table2 t2 ON t1.custid = t2.id;

But I get the same output. Is there any difference between them internally in their working ? or are both same!?

但我得到了相同的输出。他们的工作内部有什么区别吗?或者都是一样的!?

1 个解决方案

#1

The OUTER keyword is optional across most popular SQL distributions, which means there is absolutely no difference between a LEFT JOIN and a LEFT OUTER JOIN

OUTER关键字在大多数流行的SQL发行版中是可选的,这意味着LEFT JOIN和LEFT OUTER JOIN之间绝对没有区别。