How to reduce x select to 1 select? - postgresql

I have the following 3 selects and I want to improve performance, what can I do?
select object into lastUpdate
from data
where predicate = '#lastUpdate'
and subject = 'subject1';
select object into latitude
from data
where predicate = '#latitude'
and subject = 'subject1';
select object into longitude
from data
where predicate = '#longitude'
and subject = 'subject1';
Thank you

You can use a JOIN:
select lu.object, lat.object, lon.object
into lastupdate, latitude, longitude
from data lu
left join data lat on lat.subject = lu.subject and lat.predicate = '#latitude'
left join data lon on lon.subject = lu.subject and lon.predicate = '#longitude'
where lu.subject = 'subject1'
and lu.predicate = '#lastUpdate';

Related

How could i improve this Linq code instead of more joins?

I have this Linq code as below:
from objpath in Path
join objOriginalStation in Station on objpath.OriginalStationID equals objOriginalStation.StationID
join objDestinationStation in Station on objpath.DestinationStationID equals
objDestinationStation.StationID
join objVia1Station in Station on objpath.Via1StationID equals objVia1Station.StationID
join objVia2Station in Station on objpath.Via2StationID equals objVia2Station.StationID
select new ViewModels.PathViewModel
{
PathID = objpath.PathID,
SubnetworkID = objpath.SubnetworkID,
Distance = objpath.Distance,
DestinationStationID = objpath.DestinationStationID,
OriginalStationID = objpath.OriginalStationID,
Via1StationID = objpath.Via1StationID,
Via2StationID = objpath.Via2StationID,
Version = objpath.Version,
OriginalStationName = objOriginalStation.StationName,
DestinationStationName = objDestinationStation.StationName,
Via1StationName = objVia1Station.StationName,
Via2StationName = objVia2Station.StationName,
};
but I thought it's not perfect and I want to improve it, anybody has suggestion?

How to select from subquery if column contains a specific value in postgre

I would like to ask if it is possible to select again from a result set if a column contains a specific value?
For example, from the below query I want to select it as subquery and check if that subquery's first column contains both 2 and 3 result. Otherwise, no values should be return.
select e.evaluator_id, ROUND(avg(cast(e.rating_score as int))::numeric,1)::varchar, c.q_category_name
from tms.t_evaluation e
inner join tms.m_q_category c
on e.nendo=c.nendo
and e.q_category_id = c.q_category_id
and c.delete_flg = '0'
inner join tms.m_q_subcategory qs
on e.q_category_id = qs.q_category_id
and e.q_subcategory_id = qs.q_subcategory_id
and c.nendo = qs.nendo
and qs.delete_flg = '0'
where e.nendo = '2018'
and e.empl_id = 'empl05'
and e.delete_flg = '0'
and e.evaluator_id in ('2' , '3')
group by e.empl_id, e.nendo, e.q_category_id,
c.q_category_name, e.evaluator_id, e.history_no
Result contains both 2 and 3 in first column. Is this possible?
select e.evaluator_id, ROUND(avg(cast(e.rating_score as int))::numeric,1)::varchar, c.q_category_name
from tms.t_evaluation e
inner join tms.m_q_category c
on e.nendo=c.nendo
and e.q_category_id = c.q_category_id
and c.delete_flg = '0'
inner join tms.m_q_subcategory qs
on e.q_category_id = qs.q_category_id
and e.q_subcategory_id = qs.q_subcategory_id
and c.nendo = qs.nendo
and qs.delete_flg = '0'
where e.nendo = '2018'
and e.empl_id = 'empl05'
and e.delete_flg = '0'
and e.evaluator_id in (select case when evaluator_id=2 or evaluator_id=3 then evaluator_id else null from t_evaluation order by evaluator_id asc)
group by e.empl_id, e.nendo, e.q_category_id,
c.q_category_name, e.evaluator_id, e.history_no

Implementing Concat + RANK OVER SQL Clause in C# LINQ

I need to implement the following T-SQL clause ....
SELECT
CONCAT( RANK() OVER (ORDER BY [Order].codOrder, [PackedOrder].codPackedProduct ), '/2') as Item,
[Order].codOrder as [OF],
[PackedOrder].codLine as [Ligne],
[PackedOrder].codPackedProduct as [Material], ----------------------
[Product].lblPProduct as [Product],
[PackedProduct].lblPackedProduct as [MaterialDescription],
[PackedOrder].codPackedBatch as [Lot],
[Product].codCustomerColor as [ReferenceClient],
[PackedOrder].nbrPackedQuantity as [Quantity],
[PackedOrder].nbrLabelToPrint as [DejaImprime]
FROM [Order] INNER JOIN PackedOrder
ON [Order].codOrder = PackedOrder.codOrder INNER JOIN Product
ON [Order].codProduct = Product.codProduct INNER JOIN PackedProduct
ON PackedOrder.codPackedProduct = PackedProduct.codPackedProduct
Where [Order].codOrder = 708243075
So Far, I'm able to do:
var result =
from order1 in Orders
join packedorder1 in PackedOrders on order1.codOrder equals packedorder1.codOrder
join product1 in Products on order1.codProduct equals product1.codProduct
join packedproduct1 in PackedProducts on packedorder1.codPackedProduct equals packedproduct1.codPackedProduct
where order1.codOrder == _order.codOrder
select new FinishedProductPrintingM
{
OF = order1.codOrder,
Ligne = packedorder1.codLine,
Material = packedorder1.codPackedProduct,
Produit = product1.codProductType,
MaterialDescription = packedproduct1.lblPackedProduct,
Lot = packedorder1.codPackedBatch,
RéférenceClient = product1.codCustomerColor,
Quantité = packedorder1.nbrPackedQuantity,
Déjàimprimé = packedorder1.nbrLabelPrinted
};
Please let me know if its possible or not. I need to display the Items in such a way.Please feel free to add your valuable comments.
I am not aware how to use concat and Rank over function in LINQ.
Can anyone help me to convert my SQL query into LINQ?

Returning distinct columns from left outer join in db2

SELECT
nzy.NZPYYD
,nzy.NZZSYG
,nzy.NZJRYG
,acn.ANITCD
FROM
ACNTRA acn
LEFT OUTER JOIN NZYTFL nzy
ON (
nzy.NZCNO1 = acn.ANCNO1
AND nzy.NZCNO2 = acn.ANCNO2
AND nzy.NZCNO3 = acn.ANCNO3
AND nzy.NZCNO4 = acn.ANCNO4
AND nzy.NZCNO5 = acn.ANCNO5
AND nzy.NZSLKI = acn.ANSLKI
AND nzy.NZDLTM = ''
)
WHERE
acn.ANDLTM = ''
AND acn.ANTKCD = '1029'
AND nzy.NZTXKB = 1
The problem here is it gives 2 rows result.I want to get one unique row from the result of left outer join .Any help?
If both rows are identical, try
SELECT DISTINCT
nzy.NZPYYD
,nzy.NZZSYG
,nzy.NZJRYG
,acn.ANITCD
If not, you can try to SUM(), CONCAT(), MAX() or whatever the column with different values.
Difficult to be more precise without a sample output.

How to join the tables in linq to sql?

Table1 :
userid name address
1 venkat srinagr
2 venkatesh sainagar
Table2:
id userid lat lon
1 1 14.000 15.000
2 2 14.3526 15.3698
by passing "venkat" as parameter then need to pull all matching records and his userid,name,lat,lon.
in above table1 "venkat" contains in both rows then need to pull 2 records.how to get userid,name,lat,lon for all matching rows..
for sigle record i am able to get.but there are multiple rows how to get please tell me....
var result = from p in cxt.Table2
where p.Table1.Name.Contains(name)
select new
{
p.Users.User_Id,p.Users.Name,p.Latitude,p.Longitude
};
Im sure someone will say this is not the most effective way but this is how i would do it.
string InputString = "venkat";
var tab =(from a in db.tablea
from b in db.tableb
where a.userid == b.userid && a.name == InputString
select new
{
UserID = a.userid,
Username = a.name,
Latitude = b.lat,
Longditude = b.lon
}).FirstOrDefault();
FirstOrDefault() is only if you want to force only one output or null,
if you want a collection of some sort, then just remove it.