Just I want to know how to enable the search by product name in the item number look up in the purchase order and sales order screen
You'll need a modification for that as this field is only a 'display' field. The actual product name is saved in a separate table per language. You can however search directly on the search name.
In AX2012 R3 you can use the keyword search for this.Only available for sales orders though.
just change the field name in lookup method like this:
You can use 'Search name' column for searching item using name
we did it by creating a view that has inventtable, ecoresproduct and ecoresproducttranslation tables respectively and then add range on the last table on langauageid with a value of your required language ... and then use this view in the form datasources with outerjoin link type with salesline or purchline tables.
and then, add the field from the view which will be searchable ...