1.左外连接left join / left outer join --左外连接left join/left outer joinselect*fromA1select*fromA2--下面2句的结果一样:select*fromA1leftjoinA2ONA1.ID=A2.IDselect*fromA1LEFTOUTERJOINA2ONA1.ID=A2.ID 结果: 2.右外连接right join / right outer join --右外连接right join/right outer join...
其中,外连接分为:左外连接(LEFT OUTER JOIN)、右外连接(RIGHT OUTER JOIN)、全外连接(FULL OUTER JOIN),其中外连接的“OUTER”关键字可以省略不写。 例:表A有列ID,值为: 1 2 3 4 表B有列ID,值为: 3 4 5 6 1.内连接(显示左右两表能完全匹配的数据): select A.ID, B.ID from A INNER JOIN ...
SQL Server implements logical join operations, as determined by Transact-SQL syntax: Inner join Left outer join Right outer join Full outer join Cross join הערה For more information on join syntax, seeFROM clause plus JOIN, APPLY, PIVOT (Transact-SQL). ...
SELECT * FROM Table1 t1 FULL OUTER JOIN Table2 t2 ON t1.Col1 = t2.Col1 SELECT * FROM Table1 t1 FULL OUTER JOIN Table2 t2 ON t1.ID = t2.ID WHERE t1.ID IS NULL OR t2.ID IS NULL CROSS JOIN: 交叉连接不需要任何连接条件。这个会把两个表的的数据进行笛卡尔积操作。 SELECT * FROM...
The Left join (or left outer join) is one of the most commonly used join statement in SQL Server. A join lets us combine results from two or more tables into a single result set. The left join includes all the results from the left table and includes only the matching rows from the ...
SQL Server中的LEFT JOIN与LEFT OUTER JOIN 在SQL Server中,LEFT JOIN和LEFT OUTER JOIN是用来从左表中的每一行中返回数据,即使在右表中没有匹配的行。LEFT JOIN和LEFT OUTER JOIN是相同的,它们之间没有区别。 LEFT JOIN和LEFT OUTER JOIN的语法如下: 代码语言:txt 复制 SELECT column_name(s) FROM tab...
Example: Let us consider both our tables from the previous examples. Herestudentwill act as the left table andmarkswill act as the right table. All the rows from both tables are returned. This can be done using theFULL JOINclause using the below query. ...
SQL JOIN 的类型 左连接、内连接、完全连接、自连接和交叉连接是其他五种主要连接类型。 为了与数据库连接,我们必须在语句中显式或隐式地提供连接类型。 这是通过使用诸如“LEFT JOIN”、“INNER JOIN”和“FULL OUTER JOIN”等术语来实现的。 每个类别都有自己的一组应用程序。 希望下面的比较表可以帮助您识别它...
join操作 inner join:只返回连接条件匹配上的数据 outer join left:左表为基准 right:右表为基准 full:左右两表数据都会查询出 select e.empno, e.ename, e.deptno, d.dname from emp e join dept d on e.deptno = d.deptno; 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. HiveServer2 = HS2 Hive...
SQL OUTER JOIN – left outer join example The following query selects all customers and their orders: SELECTc.customerid, c.companyName, orderidFROMcustomers cLEFTJOINorders oONo.customerid = c.customeridORDERBYorderidCode language:SQL (Structured Query Language)(sql) ...