SQLPlus connection without tnsnames.ora

You can connect using sqlplus with user/pwd@tnsname, or with tnsname string directly as:

sqlplus  user/pwd@'(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=<host>)(PORT=1521)))(CONNECT_DATA=(SID=<sid>))'


This is cumbersome, and has a lot of problem on unix, since brackets "(" and ")" need backslashes.   Since Oracle 10g, there's a better way:  

  
sqlplus user/pwd@//host:1521/sid

I feel it's very useful, so noted down for future use.