Check if field is numeric, then execute comparison on only those field in one statement?

Question

This may be simple, but I am no SQL whiz so I am getting lost. I understand that sql takes your query and executes it in a certain order, which I believe is why this query d

Answer 1

try this:

select * from purchaseorders
where try_cast(purchase_order_number as int) >= 7

Answer 2

does this work for you?

select * from purchaseorders
where (case when IsNumeric(purchase_order_number) = 1
       then cast(purchase_order_number as int)
       else 0 end) >= 7

Answer 3

You can do a select with a subselect

select * from (
select * from purchaseorders
where IsNumeric(purchase_order_number) = 1) as correct_orders
where cast(purchase_order_number as int) >= 7