update Informix table with joins

Question

Is this the correct syntax for an Informix update?

update table1
set table1.code = 100
from table1 a, table2 b, table3 c
where a.key = c.key
a.no = b.no
a.ke         


        

Answer 1

For Informix SE 7.25...

1. UPDATE ... FROM ... syntax does not exist
2. You also "Cannot modify table or view used in subquery" which is given when using Rockallite's answer

Another solution would be to break it down into two queries:

First, get the ROWIDs for the required records (filtered on multiple tables):

SELECT a.ROWID
  FROM table1 a, table2 b, table3 c
 WHERE a.key = c.key
   AND a.no = b.no
   AND a.key = c.key
   AND a.code = 10
   AND b.tor = 'THE'
   AND a.group = 4183
   AND a.no IN ('1111','1331','1345')

Put the result into a comma separated string.

Then, update only those records for the main table where the ROWID was found in the first query:

UPDATE table1 a
   SET a.code = 100
WHERE a.ROWID in ([comma separated ROWIDs found above])