Re: Q: Does any ANSI-SQL standard address multi-column updates ?

>> Does anyone have information or a site where I can learn more about
which ANSI-SQL standard or level formalizes/blesses/requires multi-column updates using multi-column lookup? <<

The SQL-99 standard has syntax for a row constructor in the UPDATE statement; you can get a book on SQL-99 from Amazon.com or Fatbrain.com for details. Working from memory, it is something like:

 UPDATE Target

    SET ROW (a,b,c,..)

• (SELECT x,y,z, ... FROM Source WHERE ...) WHERE ...;