Alternative to Index + Seek on Access/DAO Using SQL Server/ADO - sql-server

Question

I'm converting an Excel app from a local MS Access backend (with DAO) to SQL Server running on Azure (with ADO).
A common task I perform with DAO is the index + seek method to scan a large amount of input rows (~10,000, and using multi field indexes), check for matching records in the database, and update or add new records as required. The NoMatch property of the Seek method works very nicely when deciding to add or update.
This seems like it should be pretty simple with SQL Server, but I can't seem to find a good solution that lets me check for matches, add or update, and use multi column indexes.
Downloading the table to memory then doing a batch update would be fine, but ADO's Find method doesn't seem as good as index + seek, and it can't use multi columns. Connecting to SQL Server with an ADO provider that supports index seek would also work (Jet 4.0?) but I can't find examples of that either.
Am I missing something obvious? What is the best way to check and add or update large number of rows to SQL Server? Thanks
Edit:
Here's a simple example of the operation I'm doing currently in Access/DAO:
Set rs = db.OpenRecordset("TableName", dbOpenTable)
With rs
.Index = "MultiFieldIndex"
'Loop through the input data
For i = 1 To 10000
.Seek "=", Criteria1, Criteria2
If Not .NoMatch Then
'Found a match, just update specific fields
!Field1 = a
!Field2 = b
Else
'No match found, add a new record then populate
.AddNew
!Field3 = c
!Field4 = d
End If
.Update
Next i
End With
Whats the best way to do something like this only with SQL? I'd still probably start with loading a disconnected recordset of the full target table, but not sure how to update a few thousand records when I don't know if I'll need to update or add new, or the values of the input criteria. How do I find the rows I need to update/check without index + seek?
OR can I create a temp table in memory with only the input data then somehow just 'merge' that table to the database and the db will figure out how to update or add?
I feel like this should be a pretty basic procedure, but maybe I'm just missing some fundamental SQL concept?
Thanks for all the help!

Answer 1

The solution would be to write an SQL query
create procedure dbo.prc_TableNameUpdIns (#parm1 int, #parm2 int)
AS
IF EXISTS (SELECT * from MyTable WHERE A = #parm1 AND B = #parm2)
UPDATE ...
ELSE
INSERT....
GO
(you could use merge but I advise against it)
And you call the SP by creating an AdoConnection (in VBA)
dim myAdoConnection as ADOConnection
dim X as Integer, Y as Integer
X = 7
Y = 8
'SET the myAdoConnection
'Calling the proc
myAdoConnection.prc_TableNameUpdIns X, Y
Processing as much code as possible in the SQL is much preferable. The only time you need to do this type of ADO manipulation is when you need to update the form only and not necessarily the database itself.
About ADO connection
And research the subject some more, this is only a pointer