Dear Experts

Table Zone has two fields as

Zone c(1)
Name c(30)

And data in table as follows

zone-----name
A---------Eric
B---------Bill
C---------Nomi
E---------Rich

Form’s Activate event has following codes

select zone
index on zone to zone1
go top
thisform.GRID1.RecordSource="zone"
thisform.grID1.COLUMN1.ControlSource="zone.zone"
thisform.GRID1.COLUMN2.ControlSource="zone.name"

Grid1 has Allowaddnew=.t.

I add data into zone table through grid but it accept duplicates

I want column1 must not accept duplicate values

Suppose Column1 has “B” then it must not allow “B” to enter.
What validation rule should I apply on column1?
Or there is some other methed exists?

Please help