How to get only numbers in a column in SQL server? using ISNUMERIC function ?

Q  How to get only numbers in a column in SQL server ?

 Let me explain problem.
     I have a table like this in this table the column(Pin No) have invalid data when i write a query i want only correct pin number rows how to do that.

i will use ISNUMERIC function to achieve this result .

ID	User_name	Pin no
1	Todd	517408
2	sara	Pin no
3	Mark	pin 516
4	Kera	506789

create a table in sql server:-

create table user (id int ,User_Name varchar(20), pinno varchar(7))

Go

insert into user values (1 ,'Todd', '517408')

insert into user values (2, 'sara', 'Pin no')

insert into user values (3, 'Mark', 'pin 516')

insert into user values (4, 'Kera', '506789')

write a query to get only correct pin number rows

select * from usser

where ISNUMERIC(pinno)=1

ISNUMERIC function will return number rows = 1 reming all =0

eg. select id , Usser_Name ,pinno, ISNUMERIC(pinno) as num from usse