SQL query Exists AND NOT Exists - mysql

Question

I have a table where I need to insert the data from a view which has 2 conditions :
1) Insert those data in a table where pk is unavailable in a transaction table but is available in the view 2) if pk is there but data is different from the view then insert those data also
Insert into table A
a,
b,
c,
d
SELECT
a,
b,
c,
d
from View sa
WHERE not Exists
(Select * FROM table A q
where SA.a = q.a )
OR
CASE WHEN Exists
(Select * FROM table A q
where SA.a = q.a
AND
SA.b <> q.b
OR SA.c <> q.c
OR SA.d <> q.d
)
Any help appreciated!

Answer 1

I believe this is the proper format for your INSERT with SELECT for Netezza. I removed the invalid CASE expression and there should be no other syntax errors, but not sure about the logic:
Insert into tableA (a,b,c,d) (
SELECT a,b,c,d
from View sa
WHERE not Exists
(Select * FROM tableA q
where SA.a = q.a
)
OR Exists
(Select * FROM tableA q2
where SA.a = q2.a
AND SA.b <> q2.b
OR SA.c <> q2.c
OR SA.d <> q2.d
)
)
Edit: I think it may have been complaining about the re-use of the q table alias.

Answer 2

As a general rule, correlated subqueries are not for Netezza. Obviously you can use them in many cases, but often at the cost of turning an MPP platform into a serial processor. Bad.
You can rewrite your insert a number of ways, but this seems the clearest to me. I have no idea what this logic is trying to do, but I replicated it nonetheless. You may have an issue if view contains duplicates; this can be addressed with a little more knowledge of your data.
insert into tableA (
a
,b
,c
,d
)
select
viw.a
,viw.b
,viw.c
,viw.d
from
view viw
join tableA tba on
(viw.a = tba.a)
or (
viw.a = tba.a
and viw.b <> tba.b
or viw.c <> tba.c
or viw.d <> tba.d
)
You could remove the possibility of view duplicates by inserting into tableA from an actual table and use the rowids found there. Perhaps something like this:
create temporary table temp_view as
select * from view
distribute on (some_key);
Then collect rowids to insert like so:
insert into tableA (
a
,b
,c
,d
)
with mar as ( --Match 'a' records.
select
viw.rowid insert_rowid
from
temp_view viw
join tableA tba using (a)
), mnb as ( --Match against 'b'
select
viw.rowid
from
temp_view viw
join tableA tba on
viw.a = tba.a
and viw.b <> tba.b
or viw.c <> tba.c
or viw.d <> tba.d
), rws as ( --All rowids.
select * from mar
union select * from mnb
)
select
a
,b
,c
,d
from
temp_view viw
join rws on rws.insert_rowid = viw.rowid;