How to do a Dlookup on the table before inserting

[Syphonics via AccessMonster.com]

In my order form I have a button name "Total Amount". Upon click, different
fields values from my order form will be inserted into a table name
"Transactions"

One of the field that will be inserted is the InvoiceID field.
This InvoiceID field from my order form will be inserted into the table
"Transactions" under a field name "Descriptions"
Can I do a check on my table "transactions" under the field name
"descriptions" for the invoiceID upon clicking on the button "Total Amount".
Hence the command will be before the inserting.
And I need to use a wildcard because the "Descriptions" has a few other field
values as well.

Thank you