Update Record In Database If Exists Otherwise Insert

I am Working on a Query to Update Record in the Database if Exists Otherwise Insert. I have 2 tables in the database Receipt table and Inventory Account Table.

For Receipt Table there is Form which is used to Insert Data into the Receipt Table(SQL TABLE). Behind the Button Click Event with the Receipt Table Insertion Query I Write a Select Query to Get data from Inventory Account Table Group By Part Number and Location in a recordset.

Code:
objmyrecordset.Open "select [Part Number],sum([Quantity Received]) as TotalQuantity,[Move From] from [5_PO_RECEIPT_TABLE_DATABASE] group by [Part Number],[Move From] ", objMyConn, adOpenStatic

objmyrecordset.MoveFirst
Do
strSQL = "select Count(*) from [Inventory_Account_Move_Table] where [Part Number] = '" & objmyrecordset![Part Number] & "' and [Location]= '" & objmyrecordset![Move From] & "';"

[Code] .......

I used the Above Code to Complete my task. The Problem is It is Adding the Correct Values into the Inventory Account Table But It is Not Updating the Previous Records. it sum all the Values in Receipt Table based on Part Number and Location but it insert this record in New Line. I want it to Update the Previous record for same part Number and Location.