The term "install" may be a little improper for Oracle Instant Client, because the packages are all zipped and portable, there's no need to actually install on OS-level. Let's see what the official document says about the steps:
- Download the appropriate Instant Client packages for your platform.
- Unzip the packages into a single directory, e.g. C:\instant_client_19.
- Set your environment variable PATH on Windows) to the directory created in Step 2.
- Start your application.
That is to say, you must download Basic or Basic Lite Package first as a base for Oracle client. After that, you can download other packages for additional functions.
All downloads are zipped file. You have to unzip them to the destination of your client. Please unzip the Basic package first and proceed the others.
For Windows, you may add the instant client directory to PATH environment variable for your need.
The "application" means utilities or tools like SQL*Plus, Toad for Oracle, or PL/SQL Developer, etc.
Further reading: Difference between Oracle Client and Oracle Instant Client
In my opinion, you have to download at least two packages:
- Instant Client Package - Basic
- Instant Client Package - SQL*Plus
Additionally, you may download:
- Instant Client Package - JDBC Supplement
Take mine as an example, I unzipped all the above packages into C:\instant_client_19. Set the PATH environment variable. And use sqlplus to test the connection.
Please note that, some releases of Oracle instant client might require the latest Microsoft Visual C++ Redistributable to make them work.
Also, you may find out there's no tnsnames.ora and sqlnet.ora like the old days. Please use Easy Connect Naming Method instead to connect your databases.
If you insist to use Net Service Names (i.e. TNS, Local Naming), you have to create your own TNS_ADMIN environment variable.
If you met ORA-03134 in your tools (e.g. TOAD) when connecting to the database, you probably need to look for lower versions of Oracle Instant Client.
ORA-03134: Connections to this server version are no longer supported
Database tools like SQL developer, Toad for Oracle or PL/SQL developer may detect no TNS afterwards, you should additionally set up them properly.