查询 MySQL 数据库以回显最高自动递增数字?
mysqlmysqli database
让我们首先创建一个 ID 为 auto_increment 的表 −
mysql> create table DemoTable ( UserId int NOT NULL AUTO_INCREMENT PRIMARY KEY, UserName varchar(20) ); Query OK, 0 rows affected (0.56 sec)
使用 insert 命令在表中插入一些记录 −
mysql> insert into DemoTable(UserName) values('John');
Query OK, 1 row affected (0.11 sec)
mysql> insert into DemoTable(UserName) values('Larry');
Query OK, 1 row affected (0.35 sec)
mysql> insert into DemoTable(UserName) values('Chris');
Query OK, 1 row affected (0.13 sec)
mysql> insert into DemoTable(UserName) values('Bob');
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable(UserName) values('Carol');
Query OK, 1 row affected (0.17 sec)
mysql> insert into DemoTable(UserName) values('David');
Query OK, 1 row affected (0.15 sec)
mysql> insert into DemoTable(UserName) values('Robert');
Query OK, 1 row affected (0.20 sec)
以下是使用 select 语句显示表中的所有记录的查询 −
mysql> select *from DemoTable;
这将产生以下输出 −
+--------+----------+ | UserId | UserName | +--------+----------+ | 1 | John | | 2 | Larry | | 3 | Chris | | 4 | Bob | | 5 | Carol | | 6 | David | | 7 | Robert | +--------+----------+ 7 rows in set (0.00 sec)
以下查询用于回显最高自动递增数字 −
mysql> select *from DemoTable order by UserId desc limit 0,1;
这将产生以下输出，显示最高自动递增值 −
+--------+----------+ | UserId | UserName | +--------+----------+ | 7 | Robert | +--------+----------+ 1 row in set (0.00 sec)
