Question

I am using the substring function in a case statment to return all numbers between ‘B0’ – ‘B9’

WHEN SUBSTRING (postcode, 1, 2) like 'B[0-9]'

but i do not want to return the number ‘B5’ in this list. I can get it working as this

WHEN SUBSTRING (postcode, 1, 2) like 'B[0-4]'
WHEN SUBSTRING (postcode, 1, 2) like 'B[6-9]'

but is there a way to add this to one line like the following?

WHEN SUBSTRING (postcode, 1, 2) like 'B[0-9]' and not like 'B5'

EDIT:

how would you do this if you where dealing with numbers between 0-100 so the sql would be like

WHEN SUBSTRING (postcode, 1, 3) like 'B[0-9][0-9]'

but you did not want to include 16 and 17?

Answer 1

WHEN SUBSTRING (postcode, 1, 2) like 'B[012346789]' -- No "5"

LIKE patterns are awesome. Mini regex, if you will.

To carry this out to the tens place or more for numbers, you might want to consider putting these values into a table that you can use for a join, exists or in.

Or, since we’re treating the numeric portion of this column as though they were numbers and not a string, this is a sign that they might have been better stored as two columns: one for the alpha, one for the numeric.

Barring any change to your schema, you might remove the alpha characters ad-hoc so you can compare them to a range of numbers, for example:

where cast(replace(postcode, 'B', '') as int) between 0 and 15
    or cast(replace(postcode, 'B', '') as int) between 18 and 100

where cast(right(postcode, len(postcode) - 1) as int) between 0 and 15
    or cast(right(postcode, len(postcode) - 1) as int) between 18 and 100

These are just a couple of possibilities. You would know best how to massage your data.