判断mysql字段是否为空

需要注意的是，如果不指定insecure选项，则会随机生成登陆密码，在E:\mysql-5.7.16-winx64\data文件夹下，有一个 hoegh.err 文件，其中hoegh是主机名，打开会看到：
2016-10-20T09:34:56.806257Z 1 [Note] A temporary password is generated for root@localhost: p-mcI:ijR6Xg，
其中 p-mcI:ijR6Xg即为随机密码。

然后，输入 mysqld --install安装MySQL服务

我们会看到界面出现：Server successfully installed，这就说明MySQL服务安装成功。

点击(此处)折叠或打开

E:\mysql-5.7.16-winx64\bin>
E:\mysql-5.7.16-winx64\bin>mysqld --install
Service successfully installed.
E:\mysql-5.7.16-winx64\bin>

5.启动MySQL服务

输入 net start mysql 回车，就会看到： MySQL 服务已经启动成功。尝试使用root用户登录数据库，并通过show databases命令查看数据库概要信息。

点击(此处)折叠或打开

E:\mysql-5.7.16-winx64\bin>
E:\mysql-5.7.16-winx64\bin>net start mysql
MySQL 服务正在启动 .
MySQL 服务已经启动成功。
E:\mysql-5.7.16-winx64\bin>mysql -u root
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.16 MySQL Community Server (GPL)
Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
4 rows in set (0.00 sec)
mysql>

6.修改root密码

安全起见，我们修改一下root密码。

点击(此处)折叠或打开

mysql>
mysql> alter user 'root'@'localhost' identified by 'root';
Query OK, 0 rows affected (0.00 sec)
mysql>
mysql> exit
Bye
E:\mysql-5.7.16-winx64\bin>mysql -u root -proot
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.7.16 MySQL Community Server (GPL)
Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
4 rows in set (0.00 sec)
mysql>