Block transaction group update (not insert)

Hi guys,

I have a table in SQL that i would like to update in Ignition. I would like to update a block of data (10 rows, multiple columns) every time.
I set up a block group how i thought i would need to. With a block of tags linked to a column name in my table.

The problem i have is i think Ignition requires a block_id in the table to figure out which rows it needs to update. But i don’t have/want a block_id and row_id in my table.
I want to use the SerialNum as the key.

How can i do this in a block group? I noticed there is a custom update entry but i don’t really know the syntax for something like:

WHERE SerialNum = (PieceSerial tag)