Can be declared using or set of variable in Query of ORACLE SQL DEVELOPER or does this have to do with PL/SQL??????????
Also does this Example of SQL SERVER:
DECLARE @EmpIDVar INT
SET @EmpIDVar = 1234
WHERE EmployeeID = @EmpIDVar
Simplest form would be
select * from employees where employeeid = :EmpIDVar;
Execute in SQL Developer - we'll prompt you for the value.