Question

Problem:
Limit the value of a VARCHAR variable (or a column) to digits and ASCI characters, but allow variable length.
This script will not yield required result:

declare @var as VARCHAR (150)
select @var = '123ABC'

if (@var LIKE '[a-zA-Z0-9]{0,150}')
    print 'OK'
else
    print 'Not OK'  

Anyone have idea how to do this?

Answer 1

You can do this with the not carat ^, and a NOT LIKE expression.

So you say, where not like not non-alphanumeric 😉 This works for standard numbers & characters:

declare @var as VARCHAR (150)
select @var = '123ABC'

if (@var NOT LIKE '%[^a-zA-Z0-9]%')
    print 'OK'
else
    print 'Not OK'

Edit: Thanks Martin for the collation hint, if you want the characters like ý treated as non-alphanumeric add in the COLLATE as below

declare @var as VARCHAR (150)
select @var = '123ABCý'

if (@var NOT LIKE '%[^a-zA-Z0-9]%' COLLATE Latin1_General_BIN ) 
    print 'OK'
else
    print 'Not OK'