Update a hstore field in PostgreSQL database

We support a system where custom fields in the system are stored as hstore fields. Like this

select query

select udf_data from inventory

Select allOpen in new window

""LocOver"=>"", "freight"=>"0", "3M Codes"=>"", "V_Partno"=>"110SP-60", "brokerage"=>"0", "Dentsply C"=>"""

Here is the data for one record. LocOver, freight, 3M Code, V_Partno, brokerge, Dentsply are the field names in the system

I want to update

I want to update the udf_data column with the values from inventory.part_no column from the udf_data V_Partno

So the update statement should be like this:

update customers
set udf_data = misc1
where udf_data ?| '{cust_type}'

But the hstore has a particular update statement like this:

update customers set udf_data = udf_data || '"cust_type"=>"test"'::hstore

Which does not work. Can anyone help?