PL/SQL declares a cursor implicitly for all SQL data manipulation statements, including quries that return only one row. However,queries that return more than one row you must declare an explicit cursor or use a cursor for loop.Explicit cursor is a cursor in which the cursor name is explicitly assigned...
Having clause is used when you want to specify a condition for a group function and it is written after group by clause. The where clause is used when you want to specify a condition for columns, single row functions except group functions and it is written before group by clause if it is used.
Instr('120000 12 0 .125',1,'.')output 13
By using distinct