wild card and given value

hi all,

I am trying to fetch data from table PKHD which is based on certain criteria,

lets say matnr,

so wat i want is i want to write a select query that is kind of dynamic,

so when user provides matnr then query shud look for that matnr, when nt then query shud look for all matnr,

i believe i shud use range, problme is there wud many criteria nt only matnr hence i cannot write two queries checking if matnr is provided or nt,

will wait for ur expert opinion

thnaks,

RS