Declaring an alias for the target table

If the name that you declare as the alias is also a keyword of the UPDATE statement, you must use the AS keyword to clarify the syntax:

UPDATE stock AS set 
   SET unit_price = unit_price * 0.94;

The following UPDATE statement references the qualified name of a table in the target clause and in two subqueries:

UPDATE nmosdb@wnmserver1:test 
SET name=(SELECT name FROM test 
   WHERE test.id = nmosdb@wnmserver1:test.id) 
WHERE EXISTS( 
SELECT 1 FROM test WHERE test.id = nmosdb@wnmserver1:test.id 
);

The next UPDATE statement is logically equivalent to the previous example, but declares r_t an alias for the qualified table name:

UPDATE nmosdb@wnmserver1:test r_t 
SET name=(SELECT name FROM test 
   WHERE test.id = r_t.id) 
WHERE EXISTS( 
   SELECT 1 FROM test WHERE test.id = r_t.id 
);