Because the computer does not have the Oracle server side installed, so after installing Plsql still cannot connect Oracle database, download an Oracle Client tool on the Internet, is green free install, decompression is good. I put my cloud on the plate.
Instantclient_11_2.zip This file is extracted and there is a network folder, if you do not create one yourself, to the network to create an admin folder, Then place the Oracle client's Network service name profile Tnsnames.ora file in the Admin folder.
Then open plsql, do not fill in the user name and password to cancel directly, find the tool (tools) in the Toolbar Preferences (preferences) there are 2 paths need to set one is Oracle Home I set the
E:\tools\instantclient_11_2 is your instantclient_11_2.zip. The other is the OCI library my settings are E:\tools\instantclient_11_2\ Oci.dll
Finally save the settings to exit and then open the normal connection login.
About Plsql connecting to an Oracle database