根据 ID 从按降序排列的表中选择最上面的记录?
mysqlmysqli database
为此，使用 ORDER BY DESC 和 LIMIT 1。让我们首先创建表 −
mysql> create table DemoTable -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> UserName varchar(100), -> UserMessage text -> ); Query OK, 0 rows affected (1.17 sec)
使用 insert 命令在表中插入一些记录 −
mysql> insert into DemoTable(UserName,UserMessage) values('Adam','Hi');
Query OK, 1 row affected (0.92 sec)
mysql> insert into DemoTable(UserName,UserMessage) values('Chris','Awesome');
Query OK, 1 row affected (0.52 sec)
mysql> insert into DemoTable(UserName,UserMessage) values('Robert','Nice');
Query OK, 1 row affected (0.65 sec)
mysql> insert into DemoTable(UserName,UserMessage) values('David','Good Morning!!!');
Query OK, 1 row affected (0.12 sec)
使用 select 语句显示表中的所有记录 −
mysql> select *from DemoTable;
输出
这将产生以下输出 −
+----+----------+-----------------+ | Id | UserName | UserMessage | +----+----------+-----------------+ | 1 | Adam | Hi | | 2 | Chris | Awesome | | 3 | Robert | Nice | | 4 | David | Good Morning!!! | +----+----------+-----------------+ 4 rows in set (0.00 sec)
以下是从表中选择最顶部记录的查询 −
mysql> select *from DemoTable order by Id DESC limit 1;
输出
这将产生以下输出 −
+----+----------+-----------------+ | Id | UserName | UserMessage | +----+----------+-----------------+ | 4 | David | Good Morning!!! | +----+----------+-----------------+ 1 row in set (0.00 sec)
