如何从MySQL结果中选择第一个和最后一个数据行？
您可以使用MIN()和选择第一个和最后一个数据行MAX()。语法如下-
SELECT * FROM yourTableName WHERE yourColumnName = (SELECT MIN(yourColumnName) FROM yourTableName) UNION SELECT * FROM yourTableName WHERE yourColumnName = (SELECT MAX(yourColumnName) FROM yourTableName) ;
为了理解上述语法，让我们创建一个表。创建表的查询如下-
mysql> create table FirstAndLastDataDemo -> ( -> EmployeeId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> EmployeeName varchar(20), -> EmployeeAge int -> );
示例
使用insert命令在表中插入一些记录。查询如下-
mysql> insert into FirstAndLastDataDemo(EmployeeName,EmployeeAge) values('John',23);
mysql> insert into FirstAndLastDataDemo(EmployeeName,EmployeeAge) values('Bob',13);
mysql> insert into FirstAndLastDataDemo(EmployeeName,EmployeeAge) values('Larry',24);
mysql> insert into FirstAndLastDataDemo(EmployeeName,EmployeeAge) values('Sam',14);
mysql> insert into FirstAndLastDataDemo(EmployeeName,EmployeeAge) values('Mike',31);
mysql> insert into FirstAndLastDataDemo(EmployeeName,EmployeeAge) values('James',18);
mysql> insert into FirstAndLastDataDemo(EmployeeName,EmployeeAge)
values('Maxwell',28);
mysql> insert into FirstAndLastDataDemo(EmployeeName,EmployeeAge) values('David',27);
mysql> insert into FirstAndLastDataDemo(EmployeeName,EmployeeAge) values('Chris',22);使用select语句显示表中的所有记录-
mysql> select *from FirstAndLastDataDemo;
输出结果
+------------+--------------+-------------+ | EmployeeId | EmployeeName | EmployeeAge | +------------+--------------+-------------+ | 1 | John | 23 | | 2 | Bob | 13 | | 3 | Larry | 24 | | 4 | Sam | 14 | | 5 | Mike | 31 | | 6 | James | 18 | | 7 | Maxwell | 28 | | 8 | David | 27 | | 9 | Chris | 22 | +------------+--------------+-------------+ 9 rows in set (0.00 sec)
这是获取第一行数据和最后一行数据的查询-
mysql> SELECT * -> FROM FirstAndLastDataDemo -> WHERE EmployeeId = (SELECT MIN(EmployeeId) FROM FirstAndLastDataDemo) -> UNION -> SELECT * -> FROM FirstAndLastDataDemo -> WHERE EmployeeId = (SELECT MAX(EmployeeId) FROM FirstAndLastDataDemo);
输出结果
+------------+--------------+-------------+ | EmployeeId | EmployeeName | EmployeeAge | +------------+--------------+-------------+ | 1 | John | 23 | | 9 | Chris | 22 | +------------+--------------+-------------+ 2 rows in set (0.00 sec)