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.key = c.key
a.code = 10
b.tor = 'THE'
a.group = 4183
a.no in ('1111','1331','1345')
I get the generic -201 'A syntax error has occurred' message, but I can't see what's wrong.
The following answer is only valid for Informix versions before 11.10, in later versions it will raise a syntax error. For 11.10 and later versions, see this answer.
Your syntax error is table1.code:
SET table1.code = 100
You need to reference the table by the assigned alias. In this case, change it to:
SET a.code = 100
Full code
UPDATE table1
SET a.code = 100
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')