I didn't know exactly where to put this because it is primarily about SQL.

I have three tables that I am going to be using for this part.

RawData
Reconciled
Errors

Basically, I need to insert rows that didn't meet the criteria and put the whole row (with over 25-35 fields) plus one field that I want to concatenate the errors encountered. For example, id, field1, field2,... , fldErr. I would concatenate the error like 1,2,5,7 and save it all in flderr.

How would I write the sql for this insert if I want to insert one row from the RawData table into the Errors table?

Well just create an append query in the query designer and on the field line for fldErr you put something like:
Errs: [Field1] & ", " & [Field2] & ", " & [Field3]

HTH
Premy