Using Co-Related Subquery and an Aggregate Function to generate sequential numbers on the fly

Declare @t Table(Name Varchar(20),Age int)
Insert Into @t 
Select 'Name1', 20 Union All Select 'Name2', 21 Union All 
Select 'Name3', 22 Union All Select 'Name4', 23 Union All
Select 'Name5', 24

Select 
(
	Select Count(*) 
	From @t t2
    Where t2.Name <= t1.Name 
    And t2.Age <= t1.Age
 ) As Rn
 ,t1.Name
 ,t1.Age
From @t t1

Select 
(
	Select Max(1)
	From @t t2
    Where t2.Name <= t1.Name 
    And t2.Age <= t1.Age
 ) As Rn
 ,t1.Name
 ,t1.Age
From @t t1

Select 
(
	Select Sum(1)
	From @t t2
    Where t2.Name <= t1.Name 
    And t2.Age <= t1.Age
 ) As Rn
 ,t1.Name
 ,t1.Age
From @t t1

/* Result */
Rn	Name	Age
1	Name1	20
2	Name2	21
3	Name3	22
4	Name4	23
5	Name5	24