How to include a JOIN after the WHERE? - sql

Question

I need to execute a statement that follows a given Prefix.
We use a certain program, it features a 'Search Folder'. Into the Search folder, I can define an SQL query. The Folder has a built-in part of the query, which I can not modify.
The built-in part is:
Prefix Artikelfilter: SELECT * FROM CMKAT.ART WHERE 1=1 AND
Now I would like to perform the following search query:
select * from CMKAT.ART
join CMKAT.AEZ on art.artKEYI = aez.aezartkeyi
join pro on pro.prokeyi = aez.aezprokeyi
left outer join psz on pro.prokeyi = psz.pszprokeyi
WHERE psz.pszprokeyi is null
AND pro.proetykeyi = 1;
Of course, the 'SELECT *...' part is redundant, but how can I get the query to work? The JOINs are after the WHERE.
I know the developers solved this issues by creating Views, and making the selection from the view, not directly in the query.
Edit:
Exception: JdbcAccess.execute failed (ORA-00904: "KVTBEZC": ungültige ID
).
SQL:
<prefix>
SELECT /* filter art */ artkeyi, artkavkeyi, artvnrs FROM art JOIN
kav ON art.artkavkeyi = kav.kavkeyi JOIN kvt ON kav.kavkvtkeyi =
kvt.kvtkeyi JOIN kat ON kav.kavkatkeyi = kat.katkeyi WHERE
(artkavkeyi IN (587, 3075, 7, 8, 592)) AND
</prefix>
1 = 0 union all select *
from cmkat.art join cmkat.aez on art.artkeyi = aez.aezartkeyi join
pro on pro.prokeyi = aez.aezprokeyi left join psz on pro.prokeyi =
psz.pszprokeyi where psz.pszprokeyi is null and pro.proetykeyi = 1
AND katkeyi = 4 AND (katspes IN (0, 3, 1, 2))/* join-dummy */ ORDER BY
artkeyi, kvtbezc (DATABASE_EXECUTE_FAILED)

Answer 1

I guess you need right query like this:
If exists (SELECT 1 FROM CMKAT.ART WHERE 1=1)
Begin
(
Select *
From CMKAT.ART
Inner join CMKAT.AEZ on art.artKEYI = aez.aezartkeyi
Inner join pro on pro.prokeyi = aez.aezprokeyi
Left Outer join psz on pro.prokeyi = psz.pszprokeyi
WHERE psz.pszprokeyi is null AND pro.proetykeyi = 1;
)
END

Answer 2

I'd construct the SQL this way:
SELECT *
FROM CMKAT.ART
WHERE 1=1 AND EXISTS (Select 1
From CMKAT.AEZ, pro
left outer join psz on pro.prokeyi = psz.pszprokeyi
Where aez.aezartkeyi = art.artKEYI and pro.prokeyi = aez.aezprokeyi and psz.pszprokeyi is null AND pro.proetykeyi = 1
);

Answer 3

I don't know if your tool allows such construction, but you could cheat it using union all:
select * from cmkat.art where 1 = 1 and 1 = 0
union all
select cmkat.art.*
from cmkat.art
join cmkat.aez on art.artkeyi = aez.aezartkeyi
join pro on pro.prokeyi = aez.aezprokeyi
left join psz on pro.prokeyi = psz.pszprokeyi
where psz.pszprokeyi is null and pro.proetykeyi = 1;
First line removes data of original query because of 1 = 0 condition so we get only data from second part of union.
Unfortunately you can obtain only columns of art table because your tool does not allow to change selected data. But you can change it selecting some columns from joined tables instead of art columns.