I want to set the to_tsvector language (e.g.: 'French') so it uses the proper dictionary when rendering the FTS vector.
Table messages has a locale_id column, which is on the locales table. Which I then need to join the locales table to the languages table on locale_id to get the actual language name. But I'm getting an ambiguous ; error:
select * from to_tsvector(t3.language, t1.message)
inner join message as t1
inner join locales as t2 on (t1.locale_id = t2.id)
inner join languages as t3 on (t2.language_id = t3.id);
ERROR: syntax error at or near ";" LINE 1: ....id)
inner join languages as t3 on (t2.language_id = t3.id);
newer code:
select to_tsvector(t3.language, t1.message)
from message as t1
inner join locales as t2 on (t1.locale_id = t2.id)
inner join languages as t3 on (t2.language_id = t3.id);
original fix:
select * from to_tsvector(t3.language, t1.message)
inner join message as t1 on 1 = 1 /* an ON join criteria is mandatory here even if you are doing an implicit cross join */
inner join locales as t2 on (t1.locale_id = t2.id)
inner join languages as t3 on (t2.language_id = t3.id);
Related
I have three table valued parameters passed into an SP. These all contain data to filter a query. I want to join them to a table as below but only if there is data in a table valued parameter
SELECT DISTINCT TOP (1000)
Person.col1,
Person.col2,
FROM dbo.Person INNER JOIN
#tbl1 t1 ON Person.col3 = t1.val INNER JOIN
#tbl2 t2 ON Person.col4 = t2.val INNER JOIN
#tbl3 t3 ON Person.col5 = t3.val
I am aware I can do a Left Outer Join but I don't want results with NULL values. The top 1000 necessary as there is a lot of data and scanning the whole table causes performance issues
Try use coalesce to cater nulls check
SELECT DISTINCT TOP (1000)
Person.col1,
Person.col2,
FROM dbo.Person INNER JOIN
#tbl1 t1 ON coalesce(Person.col3, '111') = t1.val INNER JOIN
#tbl2 t2 ON coalesce(Person.col4 , '111')= t2.val INNER JOIN
#tbl3 t3 ON coalesce(Person.col5, '111') = t3.val
I have three table, table_1 (id), table_2(id), table_pivot(tbl1_id, tbl2_id). When I use query like this:
select *
from public.table_1 t1
left join public.table_pivot tp on tp.tbl1_id = t1.id and tp.user_id = 1
left join public.table_2 t2 on t2.id = tp.tbl2_id;
Data from table_1 is show. But when I use where condition. Like this:
select *
from public.table_1 t1
left join public.table_pivot tp on tp.tbl1_id = t1.id
left join public.table_2 t2 on t2.id = tp.tbl2_id
where tp.user_id = 1;
Data from table_1 not show.
I hope advance can help explain why?
Thanks.
Including a where clause on an outer joined table, effectively converts the join into an inner join. If there are no matching values in table_pivot, then
you will get no results at all. This is standard sql.
I'm trying to get lateral to work in a Postgres 9.5.3 query.
select b_ci."IdOwner",
ci."MinimumPlaces",
ci."MaximumPlaces",
(select count(*) from "LNK_Stu_CI" lnk
where lnk."FK_CourseInstanceId" = b_ci."Id") as "EnrolledStudents",
from "Course" c
join "DBObjectBases" b_c on c."Id" = b_c."Id"
join "DBObjectBases" b_ci on b_ci."IdOwner" = b_c."Id"
join "CourseInstance" ci on ci."Id" = b_ci."Id",
lateral (select ci."MaximumPlaces" - "EnrolledStudents") x
I want the right-most column to be the result of "MaximumPlaces" - "EnrolledStudents" for that row but am struggling to get it to work. At the moment PG is complaining that "EnrolledStudents" does not exist - which is exactly the point of "lateral", isn't it?
select b_ci."IdOwner",
ci."MinimumPlaces",
ci."MaximumPlaces",
(select count(*) from "LNK_Stu_CI" lnk
where lnk."FK_CourseInstanceId" = b_ci."Id") as "EnrolledStudents",
lateral (select "MaximumPlaces" - "EnrolledStudents") as "x"
from "Course" c
join "DBObjectBases" b_c on c."Id" = b_c."Id"
join "DBObjectBases" b_ci on b_ci."IdOwner" = b_c."Id"
join "CourseInstance" ci on ci."Id" = b_ci."Id"
If I try inlining the lateral clause (shown above) in the select it gets upset too and gives me a syntax error - so where does it go?
Thanks,
Adam.
You are missing the point with LATERAL. It can access columns in tables in the FROM clause, but not aliases defined in SELECT clause.
If you want to access alias defined in SELECT clause, you need to add another query level, either using a subquery in FROM clause (AKA derived table) or using a CTE (Common Table Expression). As CTE in PostgreSQL acts as an optimization fence, I strongly recommend going with subquery in this case, like:
select
-- get all columns on the inner query
t.*,
-- get your new expression based on the ones defined in the inner query
t."MaximumPlaces" - t."EnrolledStudents" AS new_alias
from (
select b_ci."IdOwner",
ci."MinimumPlaces",
ci."MaximumPlaces",
(select count(*) from "LNK_Stu_CI" lnk
where lnk."FK_CourseInstanceId" = b_ci."Id") as "EnrolledStudents",
from "Course" c
join "DBObjectBases" b_c on c."Id" = b_c."Id"
join "DBObjectBases" b_ci on b_ci."IdOwner" = b_c."Id"
join "CourseInstance" ci on ci."Id" = b_ci."Id"
) t
Can someone explain this to me?
I have two huge tables on which I wish to LEFT JOIN, but I think it would be more efficient to filter at the 'on' rather than the 'where'.
Select * from Table1 t1 left join Table2 t2 on t1.Id = t2.Id and t1.Enabled = 1
Rather than
Select * from Table1 t1 left join Table2 t2 on t1.Id = t2.Id where t1.Enabled = 1
The above results are not the same. No matter what I put in as filtering, it stays unaffected:
Select * from Table1 t1 left join Table2 t2 on t1.Id = t2.Id and t1.Enabled = 1
yields exactly the same results as
Select * from Table1 t1 left join Table2 t2 on t1.Id = t2.Id and t1.Enabled = 0
Also, Table1 might only have a few records where Enabled = 1, so it would be inefficient to join millions of records first and then filter to find only 10.
I can do a sub select first, but I somehow I feel it is not the right way:
Select * from (Select * from Table1 where Enabled = 1) a left join Table2 t2 on a.Id = t2.Id
Types of Joins
Left outer join All rows from the first-named table (the "left"
table, which appears leftmost in the JOIN clause) are included.
Unmatched rows in the right table do not appear.
When you move the condition to the where then t1.Enabled = 1 is applied
Do you have actual performance problems with the first query?
I have a following script to get the total unit but it gives me an error
Cannot perform an aggregate function on an expression containing an aggregate or a subquery.
Do I need to calculate SUM(ta.Qty) outside the main table?
SELECT
ta.ProductName
, SUM(ta.Total)
, SUM(SUM(ta.Qty) * ta.Unit)
FROM
tableA tA
INNER JOIN
tableB tB on tA.ID = tb.TableAID
INNER JOIN
tableC tc on ta.ID = tc.TableAID
INNER JOIN
tableD td on td.ID = tb.TableBID
GROUP BY
ta.ProductName
Here is a query in the AdventureWorks database that produces the same error (but might make some sense):
SELECT v.Name AS Vendor, SUM(SUM(p.ListPrice*d.OrderQty)+h.Freight)
FROM Production.Product p
INNER JOIN Purchasing.PurchaseOrderDetail d ON p.ProductID = d.ProductID
INNER JOIN Purchasing.PurchaseOrderHeader h ON h.PurchaseOrderID = d.PurchaseOrderID
INNER JOIN Purchasing.Vendor v ON v.BusinessEntityID = h.VendorID
GROUP BY v.Name
And here are two ways that I could rewrite that query to avoid the error:
SELECT v.Name AS Vendor, SUM(x.TotalAmount+h.Freight)
FROM (
SELECT PurchaseOrderID, SUM(p.ListPrice*d.OrderQty) AS TotalAmount
FROM Production.Product p
INNER JOIN Purchasing.PurchaseOrderDetail d ON p.ProductID = d.ProductID
GROUP BY PurchaseOrderID
) x
INNER JOIN Purchasing.PurchaseOrderHeader h ON h.PurchaseOrderID = x.PurchaseOrderID
INNER JOIN Purchasing.Vendor v ON v.BusinessEntityID = h.VendorID
GROUP BY v.Name
SELECT v.Name AS Vendor, SUM(x.TotalAmount+h.Freight)
FROM Purchasing.PurchaseOrderHeader h
INNER JOIN Purchasing.Vendor v ON v.BusinessEntityID = h.VendorID
CROSS APPLY (
SELECT SUM(p.ListPrice*d.OrderQty) AS TotalAmount
FROM Production.Product p
INNER JOIN Purchasing.PurchaseOrderDetail d ON p.ProductID = d.ProductID
WHERE d.PurchaseOrderID=h.PurchaseOrderID
) x
GROUP BY v.Name
The first query uses derived tables and the second one uses CROSS APPLY.