using WHERE with SET in an UPDATE - mysql

Question

I am new user with MySQL 5.6 and trying to UPDATE a table using NAVICAT
I trying to condition the SET statement with a WHERE. It seems I have taken the wrong approach. Can someone point me in the right direction?
UPDATE vacation_watch
INNER JOIN property_names
ON vacation_watch.Mstrfromproperty = property_names.MstrLink
INNER JOIN property_names_subnames
ON property_names_subnames.NameLink = property_names.NameLink
SET vacation_watch.Watch_Requester_Last = property_names.Name_Last,
vacation_watch.Watch_Requester_First = property_names.Name_First,
vacation_watch.Watch_Requester_Phone = property_names.Name_Phone,
vacation_watch.Emergency_Contact_Name = property_names_subnames.Sub_Name_Last WHERE property_names_subnames.Sub_Name_Type = "KEYHOLDER"
vacation_watch.Emergency_Contact_Phone = property_names_subnames.Sub_Name_Phone WHERE property_names_subnames.Sub_Name_Type = "EMERGENCY"

Answer 1

You are using two WHERE clauses and in the wrong way.
What you are looking for is actual conditional SQL. There is already an answer on SO that could help you achieving what you want to do here.
Furthermore, there can only be only one WHERE clause that applies on the global level, not at field level.
Something like:
UPDATE vacation_watch
INNER JOIN property_names
ON vacation_watch.Mstrfromproperty = property_names.MstrLink
INNER JOIN property_names_subnames
ON property_names_subnames.NameLink = property_names.NameLink
SET vacation_watch.Watch_Requester_Last = property_names.Name_Last,
vacation_watch.Watch_Requester_First = property_names.Name_First,
vacation_watch.Watch_Requester_Phone = property_names.Name_Phone,
vacation_watch.Emergency_Contact_Name =
CASE WHEN property_names_subnames.Sub_Name_Type = "KEYHOLDER"
THEN property_names_subnames.Sub_Name_Last
END
vacation_watch.Emergency_Contact_Phone =
CASE WHEN property_names_subnames.Sub_Name_Type = "EMERGENCY"
THEN property_names_subnames.Sub_Name_Phone
END
could work. I hope I got what you wanted to do correctly and my syntax is correct as I just wrote it in a text editor and didn't test it.