SQL Query Table Fields Concatenation

Hi Guys,

How do I concatenate 2 table fields?

This is my sample query

select tdsls400.*, tcmcs050.seri, tcmcs050.ffno
from tdsls400, tcmcs050.seri
where tdsls400.odat <= tdsls400.odat.t
and tdsls400.orno = tcmcs050.seri + tcmcs050.ffno

The fields that is in bold is the one that I want to combine/concatenate.

Any suggestion how to do it properly?

OR I want to trim a field how should I do it?

For example the field tdsls400.orno = "MLF1000001" how to trim this into like this "MLF1"?

Thank you in advance,