concatenation function in Webi

Hi

I have Material field and some materials are 4 digit and some are 5 digits

Users want to see zero with 4 digit material code e.g 01234 but dont want to see zeros with 5 digit code.

I have concatenated the material with 0 in the beginning of every material but since it is also showing 0 with five digit material code as well which is not acceptable.

Is there a logic I can write while concatenate on the material field that it only add 0 in front of 4 digit material but not add anything before 5 digit

for example,

Field: Material Code:

01234 ( zero before the material code)

05678 ( zero before the material code)

01000 ( zero before the material code)

87694 (no zero before the material code)

Will appreciate the help.

Thanks