i have 2 drop down list the 1st ddl contains (deptno&deptname) dept no is a 4 digitco

[Balajiselvam]

i have 2 drop down list
the 1st ddl contains (deptno&deptnam e)
dept no is a 4 digitcode.
now we must find the substring of deptno ie first 2 digits and compare it with the last two digits of 2nd ddl
and display the common fields in the ddl2.it is being done to filter the values.
using C#
can u help me with dis.

[Samuel Jones]

I need to understand if the first ddl contains a string like "#### Name of Department" or if the numbers and names are in separate ddls.