Kill connections to an Oracle Schema

You can kill all connections by running the code below. Just Replace SCHEMA with your schema name.

declare str varchar2(100);
begin
for SES in (select sid,serial# from v$session where username='SCHEMA'  )
loop
str := 'alter system disconnect session '|| '''' || to_char(SES.sid) ||','||to_char(SES.serial#)||'''' || ' ' || 'immediate';
execute immediate str;
end loop;
end;


To kill a single connection, first find the connection by running:

select * from v$session;

Then run:

alter system kill session 'sid,serial#';

where sid and serial# are extracted from your first query of v$session above.

How to run sqlplus

To run sqlplus you need 3 env var set. Set them as follows if they are not set already. ( you can check if they are set by doing "echo $ORACLE_SID" for example to see if your SID is set. )

export ORACLE_HOME=<your Oracle Home>
export PATH=%ORACLE_HOME%\bin;%PATH%
export ORACLE_SID=<your SID>

Then run the following at the command line to start sqlplus.
sqlplus /nolog

This starts sqlplus with no user logged in.