Upsert operations update rows if they already exist in a table, and insert new rows they do not already exist. Specified an Upsert operation in an APPLY statement using the expression:
INSERT FOR MISSING UPDATE ROWS;
An Upsert operation fails only if both the update and the insert fail.
Also, the following specification is usually included for Upsert operations in anticipation of missing rows:
IGNORE MISSING UPDATE ROWS