Simple examples, showing how to connect to ORACLE DB, with Java ojdbc driver, and how to make inserts without polluting ORACLE environment.
It's important to understand that polluting the ORACLE environment, without closing the opened connection, at the end, it will lock the system.
The examples are:
HelloWorld: Just a simple query to tableDUAL;WrongWay: Inserts data in tableTEST_INSERT, in wrong way: opens the connection for each insert, without closing the connection. Because of that it's polluting the ORACLE environment with tons of SESSIONS_PER_USER, until the system resources run out!CorrectWay: Just closes the balanced connection with the open ones. At least it's not polluting the ORACLE environment; but it's unnecessary opening and closing the connection for each insert;GoodWay: Opens the connection to ORACLE only one time, closing it only one time at the end of the program;BetterWay: One connection, one commit.
Tested on:
macOS Mojave 10.14.6- java:
1.8.0_66 - javac:
1.8.0_66
- java:
Oracle Linux Server 7.5Oracle Database 18c Express Edition- java:
1.8.0_151 - javac
1.8.0_151
Download ojdbc7.jar from jdbc-drivers-12c-downloads and copy it in lib/ folder.
To run the examples WrongWay, CorrectWay, GoodWay, BetterWay, execute the script in sql/create-table_test_insert.sql; it will create the table TEST_INSERT in your DB.
Copy Configure/Credentials-template.java to Configure/Credentials.java and modify the credentials you need (url, user and password).
$ cd examples/HelloWorld
$ . ../../script/compile.sh
. ../../script/run.sh
To monitor the SESSIONS_PER_USER execute the query in sql/sessions_per_user.sql
MonitorWrongWay,: 61 SESSIONS_PER_USER polluting ORACLE environment:
MonitorCorrectWay: just 3 SESSIONS_PER_USER:
Don't use this repo in production, it's only an academic collection of examples; production is on another layer. Use at your own risk.
Donations are welcome at Bitcoin address: 1Java1MmYqF3hTQmvwjtT3k8Dbc6HHd7Tv
Isidoro Ghezzi