June 17, 2013 at 4:46 pm
Hi.
I am fairly new to SQL Server and have come across this SQL Server Query at work and I am trying to understand their logic here.
Is there a more tidy way to re-write this query, I am not even sure if it is return the desired unique results or if it is return a cartisian product.
anyway professionals here is the code I am trying to work with
SELECT distinct a1.Netbios_Name0,
c1.SerialNumber0,
a1.Operating_System_Name_and0,
b1.Publisher0,
b1.DisplayName0,
b1.Version0,
b1.InstallDate0,
c1.TimeStamp
FROM v_R_System a1
inner join v_add_remove_programs b1
on a1.ResourceID = b1.ResourceID
inner join v_GS_PC_BIOS c1
on a1.ResourceID = c1.ResourceID
left outer join v_GS_CCM_RECENTLY_USED_APPS d1
on b1.ResourceID = d1.ResourceID
and b1.GroupID = d1.GroupID
GROUP BY a1.Netbios_Name0,
c1.SerialNumber0,
a1.Operating_System_Name_and0,
b1.Publisher0,
b1.DisplayName0,
b1.Version0,
b1.InstallDate0,
c1.TimeStamp
ORDER BY 1;
June 18, 2013 at 2:26 am
Hi
What don't you understand about it?
Looks like the GROUP BY is not needed (Unless its in an effort to eliminate duplicates)
Andy
==========================================================================================================================
A computer lets you make more mistakes faster than any invention in human history - with the possible exceptions of handguns and tequila. Mitch Ratcliffe
June 18, 2013 at 2:48 am
.... and the ORDER BY 1 means ORDER BY the first column expression the SELECT Statement.
Just adding this because I didn't know that not a long while ago...
June 18, 2013 at 8:37 am
Arthur Kirchner (6/18/2013)
.... and the ORDER BY 1 means ORDER BY the first column expression the SELECT Statement.Just adding this because I didn't know that not a long while ago...
To add to this, it is also a bad practice. You should not order by the ordinal position, instead you should order by the name of the column. It eliminates confusion and possible issues down the road. If the column order changes, the results will be ordered incorrectly unless you also remember to change the order by. :w00t:
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June 18, 2013 at 2:00 pm
Hi
I may be wrong, but I can't see a reason for this join
left outer join v_GS_CCM_RECENTLY_USED_APPS d1
on b1.ResourceID = d1.ResourceID
and b1.GroupID = d1.GroupID
June 18, 2013 at 4:48 pm
Hi all
yes i agree, i am not sure about the left out join thats what has confused me a bit.
would this query provide the same results?
SELECT distinct a1.Netbios_Name0,
c1.SerialNumber0,
a1.Operating_System_Name_and0,
b1.Publisher0,
b1.DisplayName0,
b1.Version0,
b1.InstallDate0,
c1.TimeStamp
FROMv_R_System a1,
v_add_remove_programs b1,
v_gs_PC_bios c1,
v_gs_ccm_recently_used_apps d1
where a1.resourceid = b1.resourceid
and a1.resourceid = c1.resourceid
and b1.resourceid = d1.resourceid
and b1.groupid = d1.groupid
ORDER BY a1.netbios_name0;
June 18, 2013 at 6:37 pm
Oracle765 (6/18/2013)
Hi allyes i agree, i am not sure about the left out join thats what has confused me a bit.
would this query provide the same results?
SELECT distinct a1.Netbios_Name0,
c1.SerialNumber0,
a1.Operating_System_Name_and0,
b1.Publisher0,
b1.DisplayName0,
b1.Version0,
b1.InstallDate0,
c1.TimeStamp
FROMv_R_System a1,
v_add_remove_programs b1,
v_gs_PC_bios c1,
v_gs_ccm_recently_used_apps d1
where a1.resourceid = b1.resourceid
and a1.resourceid = c1.resourceid
and b1.resourceid = d1.resourceid
and b1.groupid = d1.groupid
ORDER BY a1.netbios_name0;
Given that it appears that the v_gs_ccm_recently_used_apps table isn't used to filter or return any results in the original, I would say that it could be removed from the query altogether.
In your query above you are changing the outer join to this table an inner join. This may affect (reduce) the rows returned.
June 18, 2013 at 7:27 pm
Hi micky t.
I have done that and all seems fine now
thanks everyone.
not sure how to close this as resolved
June 19, 2013 at 1:52 am
mickyT (6/18/2013)
Oracle765 (6/18/2013)
Hi allyes i agree, i am not sure about the left out join thats what has confused me a bit.
would this query provide the same results?
SELECT distinct a1.Netbios_Name0,
c1.SerialNumber0,
a1.Operating_System_Name_and0,
b1.Publisher0,
b1.DisplayName0,
b1.Version0,
b1.InstallDate0,
c1.TimeStamp
FROMv_R_System a1,
v_add_remove_programs b1,
v_gs_PC_bios c1,
v_gs_ccm_recently_used_apps d1
where a1.resourceid = b1.resourceid
and a1.resourceid = c1.resourceid
and b1.resourceid = d1.resourceid
and b1.groupid = d1.groupid
ORDER BY a1.netbios_name0;
Given that it appears that the v_gs_ccm_recently_used_apps table isn't used to filter or return any results in the original, I would say that it could be removed from the query altogether.
In your query above you are changing the outer join to this table an inner join. This may affect (reduce) the rows returned.
Be careful those are old ANSI-89 Joins, its much better to use the ANSI-92 Joins
==========================================================================================================================
A computer lets you make more mistakes faster than any invention in human history - with the possible exceptions of handguns and tequila. Mitch Ratcliffe
June 19, 2013 at 6:11 am
What any means is that the FROM clause is just listing the tables and not the relationships between them and relies on the WHERE clause for its joining criteria.
Old Style
Select
A.somecol,
B.othercol
FROM
A,
B
WHERE
A.foreignkey = B.primaryKey
AND
A.somecol = 'somevalue'
New Style
Select
A.somecol,
B.othercol
FROM
A
INNER JOIN
B on B.primaryKey = A.foreignKey
WHERE
A.somecol = 'somevalue'
June 19, 2013 at 1:45 pm
Oracle765 (6/18/2013)
Hi allyes i agree, i am not sure about the left out join thats what has confused me a bit.
Read this http://msdn.microsoft.com/en-us/library/ms191472(v=sql.105).aspx
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