After installing Oracle, you cannot start Oracle with the Sqlplus command under DOS commands.

just like completing the JDK installation, you need to configure the environment variable java_home and path for the system to let the system know the Javac command inside the JDK. Similarly, there is a process required to install Oracle. When you install Oracle under normal conditions, the system Setup program automatically configures environment variables, but if an error occurs while configuring environment variables during installation, or if you remove the system to an Oracle-configured environment variable after the installation is successful, Causes the system not to recognize the Sqlplus command under DOS commands and cannot use it.

WORKAROUND: First locate your Oracle's installation directory D:\app\Administrator\product\11.2.0\dbhome_1\BIN to see if there is a sqlplus.exe. If present, do the following:
1) DOS command: Skip to install Oracle's D-disk directory->d:\sqlplus directly, but if every time you run Oracle all the hops are unscientific .... Therefore, it is recommended to configure the system environment variables using the following methods:

2) Configure Oracle System environment Variables : Right-click Computer, properties, advanced system settings, environment variables, PATH (double-click)
Path:c:\program Files\java\jdk1.8.0_111\bin; (The bin directory of the JDK) D:\app\Administrator\product\11.2.0\dbhome_1\BIN (Oracle's BIN directory)

Complete the configuration.

After installing Oracle, you cannot start Oracle with the Sqlplus command under DOS commands.