I'm totaly new in oracle, so sorry for my probably stupid question... I have two instances on oracle server, when I'm connecting to the server via sqlplus in default opens connection to instance X but I need to change instance to Y. How can I do that?

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    How exactly are you connecting via SQL*Plus? Normally, you'd do something like sqlplus user/password@TNS_alias in which case you'd have one TNS alias for X and one for Y. If you are telnetting to the database server and connecting without a TNS alias, your ORACLE_SID environment variable controls which SID is the default. You could change that every time but it probably makes more sense to specify a TNS alias explicitly. – Justin Cave Oct 29 '19 at 20:05

Assuming that you already went through the steps of connecting to your Oracle DB using SQL*PLUS, here is how to switch from one database to another within your instance:


The best way (in my opinion) to connect to an specific database would be to specify the DB your are connecting to in the connection string.



  • Switching the container is something different than switching the instance – a_horse_with_no_name Nov 12 '19 at 7:19

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