sql - Update query statement

Question

I found out something strange which works

Update **X** SET field = 'bla'
from **X**

..which doesn't really make sense

Answer 1

This general syntax is usually used for joining tables when updating (i.e., you want to update column c1 in table t1 based on column c2 in table t2). The general for is

UPDATE 
    t1
SET 
    t1.c1 = t2.c2, -- Just an example
    t1.c3 = 'something else' -- etc...
FROM 
    t1
[INNER | LEFT] JOIN t2 ON join_condition

On you example, you don't have a join clause, so it may look a bit funny, but as you noted, this is valid syntax.