How i prevent customer invoice no field data exist from updated when i transfer empty data to same field

Hi guys can any one help me in this task

I create field customer invoice no in Database B and Database A to give every group of sales invoice line unique number

this processes done IN Database B customer invoice no is sales invoice line table when this field is empty in same sales invoice no it remove value that found in database B


Database A Database B

Sales invoice line table Sales invoice line table

No customer invoice no No customer invoice no

so-30 so-30 300

When i transfer data from Database A to database B in table sales invoice line

it clear or remove 300 and become no value

How i put condition by code tell him

when import

if sales invoice line table .customer invoice no field has value

not updated

Are this possible by code please help me


Put a filiter on Field where value is blank

and update only those record …

Are this true

In before import trigger of this table i want to transfer it i write as following

setrange (CustomerInvoiceNo,"");

if find first

sales invoice line.modify