select * from musicians
where dob = '$value' and dob = '$value'

SQL> select ename from emp where deptno = &dept_number;
Enter value for dept_number: 10
old   1: select ename from emp where deptno = &dept_number
new   1: select ename from emp where deptno = 10

ENAME
----------
CLARK
KING
MILLER

SQL>

SQL> select ename from emp
  2  where hiredate between to_date('&d1', 'dd.mm.yyyy')
  3                     and to_date('&d2', 'dd.mm.yyyy');
Enter value for d1: 01.01.1987
old   2: where hiredate between to_date('&d1', 'dd.mm.yyyy')
new   2: where hiredate between to_date('01.01.1987', 'dd.mm.yyyy')
Enter value for d2: 31.12.1987
old   3:                    and to_date('&d2', 'dd.mm.yyyy')
new   3:                    and to_date('31.12.1987', 'dd.mm.yyyy')

ENAME
----------
SCOTT
ADAMS

SQL>