Connect the Oracle client to the Database Server

For beginners, there are always the following questions about the connection between client tools and database servers:

Do I have to install the Oracle database on a local machine?
If I have installed an Oracle database locally, why is it so stupid to configure a TNS to connect to the database?
If you do not need to install a database locally, how can this problem be solved?
What is the relationship between SQL * Plus, PL/SQL Developer, and Oracle databases?

To understand the relationship between the above questions and these terms, I will explain it in a clumsy analogy:
First, you need to understand two processes (Windows platform): the Oracle database process and the Oracle database service listening process. If you divide the installation phase according to the two processes, we can divide the installation phase into two phases: database background system installation and database creation, the database process and the database service listening process are created in two installation phases respectively.

After the installation in the first phase, Oracle database does not have the "real Database" function, because it is only a basic system capable of database management and cannot store data. Just like building a house, you need a land first to build a house, but it is not a house. If the Oracle database process is successfully started, how can this problem be solved? As we can see above, if I need to operate the database server, we only need the following conditions:

Know TNS, that is, database address information
Oracle Net software layer
Client application

TNS has enough knowledge. How can we make our system have the Oracle Net software layer? There are several ways:

Dedicated installation of Oracle Client software, which can be downloaded from the Oracle website
Install Oracle development tools, such as Form, Report, and Discoverer, because these software also includes the Oracle Net software layer.
Install the Oracle database with the Oracle Net software layer

What we need is a client application so that we can operate the database. SQL * Plus is an application tool that comes with many Oracle products, PL/SQL Developer is an Oracle client tool developed by a third-party company. Therefore, before using SQL * Plus or PL/SQL Developer to operate a database, we generally need to configure TNS, And to configure TNS, We need to install the Oracle Net software layer.

To sum up, we need to operate the Oracle database or develop database applications in the Oracle database environment. Our most common environment combination:

Install the Oracle Client software on the development machine so that it has the Oracle Net software layer, and then configure TNS to identify the database to be connected; install Oracle client development tools such as PL/SQL Developer. The Oracle database server system is installed on the company's server or "Far Away" and has nothing to do with developers, As long as TNS is configured.
Install the Oracle database on the development machine and the Oracle Net software layer. Configure TNS to identify the database connected to the local machine. Install the Oracle client development tool.

In this way, if you have no conditions to install an Oracle database on your machine, you can select the first solution, and then find a qualified database server or a company database server for learning, of course, the premise is to ensure network connection!