When connecting to PL/SQL, an "unable to resolve the connect identifier specified" error occurs in the oracle database (ORA-12154: TNS:could not resolve the connect identifier specified)
Solution to "Unable to parse the specified connection identifier":
First open plsql, click Cancel to enter the main interface
Then select the toolbar tools-->preferences..(as shown in the picture)
Configure the two pieces of information marked by the arrows in the picture below,
Click OK, close plsql and restart it
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