In MS Access 2010, I am building an update query (using the Query Designer).
I would like to pass the name of the column to update as a variable, at run time.
I have tried writing the SQL and running the query in VBA. This seemed like the easiest way… however the SQL to complete the update becomes quite messy. I would prefer to do this in the query builder GUI .
Is it possible?
I have so far tried entering field names into the query builder:
expr1:[field_name]
Although Access prompts me for “Field_name” This results in “Cannot update ‘field_name’; field not updateable.
Also, I tried this method:
Expr1: "'" & [field_name] & "'"
which results in “‘” & [field_name] & “‘” is not a valid name; check for punctuation.. etc
Below is a screen capture the query I am trying to build.

Access’ db engine will not allow you to use a parameter as the name of the target field for your
UPDATEstatement.If you try a user-defined function instead of a parameter to provide the field name, the result will be the same … no joy.
It seems the db engine will not resolve object names when it executes a SQL statement. That limitation applies not just to field names, but table names as well. IOW, the following query will fail with an error message that it “cannot find the input table or query ‘give me a table name’“.
While that isn’t exactly the same as your situation, I suspect the reason may be. The db engine is too limited about resolving object names when it plans/executes queries.