I want to optimze the follwing query, to not use subquery to get max value:
select c.ida2a2 from table1 m, table2 c
where c.ida3a5 = m.ida2a2
and (c.createstampa2 < (select max(cc.createstampa2)
from table2 cc where cc.ida3a5 = c.ida3a5));
Any idea? Please let me know if you want to get more info.
This may be a more efficient way to write the query:
select c.ida2a2
from table1 m join
(select c.*, MAX(createstampa2) over (partition by ida3a5) as maxcs
from table2 c
) c
on c.ida3a5 = m.ida2a2
where c.createstampa2 < maxcs
I'm pretty sure Oracle optimizes this correctly (filtering the rows before the join). If you wanted to be clearer:
select c.ida2a2
from table1 m join
(select c.*
from (select c.*, MAX(createstampa2) over (partition by ida3a5) as maxcs
from table2 c
) c
where c.createstamp2 < c.maxcs
) c
on c.ida3a5 = m.ida2a2
Related
I have an inner join result that I want to save it by using with as but received an error. I'm using snowflake.
My code:
with t as (select *
from
(select ID, PRICE from DB.TABLE1
WHERE PRICE IS NOT NULL and ID = '1111') A
inner join
(select ID, BID, ACCEPTED from DB.TABLE2
WHERE BID IS NOT NULL and ID = '1111') B
ON A.ID = B.ID);
Error: SQL compilation error: syntax error line 8 at position 25 unexpected ';'.
If I only run the inner join
select *
from
(select ID, PRICE from DB.TABLE1
WHERE PRICE IS NOT NULL and ID = '1111') A
inner join
(select ID, BID, ACCEPTED from DB.TABLE2
WHERE BID IS NOT NULL and ID = '1111') B
ON A.ID = B.ID
I got this result
ID, PRICE,ID,BIDS,ACCEPTED
1111,180,1111,200,FALSE
1111,180,1111,180,FALSE
1111,180,1111,180,FALSE
1111,180,1111,100,TRUE
Any idea why I got the error message?
You use with to essentially create an alias (called a common table expression) for the query that can then be used in that specific query. All you've done is create the alias without using it. You need something like:
with t as (select *
from
(select ID, PRICE from DB.TABLE1
WHERE PRICE IS NOT NULL and ID = '1111') A
inner join
(select ID, BID, ACCEPTED from DB.TABLE2
WHERE BID IS NOT NULL and ID = '1111') B
ON A.ID = B.ID)
select * from t
Although obviously you'd usually do more complex work than that or else you'd just write the base query without using with
WITH is syntax used to introduced a common table expression. This is an expression used within a single query. It is a lot like a subquery in the FROM clause, except that it can be referenced more than once.
So a correct usage would be:
with t as (
select . . .
)
select count(*)
from t;
In other words, you need to follow the with with something that uses the CTE. Otherwise, you want to store the results in a real table -- temporary or otherwise.
To use CTE, join should be made after creating the tables.
with t as
(select ID, PRICE from DB.TABLE1
WHERE PRICE IS NOT NULL and ID = '1111') ,
t1 as
(select ID, BID, ACCEPTED from DB.TABLE2
WHERE BID IS NOT NULL and ID = '1111')
select *
from t
inner join
t1
on t.ID = t1.ID;
How can we use reference of main query result set as a source table in subquery
Table A, Table C
Select
(Select * From a)
From
(Select tabA.*
From A tabA
Join C tabC
On tabA.id = tabC.id) as a
I got invalid object a error here
Presumably, you want a common table expression (CTE):
with a as (
select tabA.*
from A tabA Join
C tabC
on tabA.id = tabC.id
)
Select (Select * from a)
From a;
That said, your query makes no sense. The scalar subquery is probably going to be returning an error, either because of the number of rows or number of columns.
if you using sqlserver than modified your query based on below query.
select * from
(select A.* from TableA A inner join TableB B on A.EmployeeID = B.EmployeeID ) a
I need to execute a query something like below.
SELECT TO_CHAR(ROWNUM),
A.Name,
B.Order,
(SELECT * FROM (
SELECT ROUND(LAST_ORDER_AMOUNT,5) FROM ORDERS WHERE ID=A.id AND REQUEST_LEVEL='N' ORDER BY O_DATE DESC)
WHERE ROWNUM =1) AS AMOUNT
FROM Table1 A LEFT JOIN Table2 B
ON A.TYPE_CODE = B.ENTITY_TYPE
But this gives me A.ID is invalid error in oracle. I need to get the first record from inner query as it will return multiple records.
Can someone please let me know how can i bind these tables to achieve my goal.
Thank you in advance.
You can rewrite subquery using WITH clause, not exactly sure on syntax but should be something like following.
WITH AmountQuery
AS (
SELECT ID
,ROUND(LAST_ORDER_AMOUNT, 5) AS AmountValue
,ROW_NUMBER() OVER ( ORDER BY O_DATE DESC ) AS RN
FROM ORDERS
WHERE REQUEST_LEVEL = 'N'
)
SELECT TO_CHAR(ROWNUM)
,A.Name
,B.Order
,C.AmountValue
FROM Table1 A
LEFT JOIN Table2 B
ON A.TYPE_CODE = B.ENTITY_TYPE
LEFT JOIN AmountQuery C
ON a.ID = c.ID
AND c.RN = 1
here is SQLFiddle to show how it works.
http://sqlfiddle.com/#!4/696b6/36
Probably, LIMIT will do the job for you selecting just one record from the subquery (It worked for me in MySQL. I do not have Oracle, but I think it may be similar). Try something like this:
SELECT TO_CHAR(ROWNUM),
A.Name,
B.Order,
COALESCE( C.AMOUNT ) as AMOUNT,
FROM Table1 A LEFT JOIN Table2 B
ON A.TYPE_CODE = B.ENTITY_TYPE
LEFT JOIN ( SELECT ROUND(LAST_ORDER_AMOUNT,5) AS AMOUNT FROM ORDERS WHERE REQUEST_LEVEL='N' ORDER BY O_DATE DESC ) C ON C.ID = A.id
group by A.id;
I am trying to change my sub-query in to a join where it selects only one record in the sub-query. It seems to run the sub-query for each found record, taking over a minute to execute:
select afield1, afield2, (
select top 1 b.field1
from anothertable as b
where b.aForeignKey = a.id
order by field1
) as bfield1
from sometable as a
If I try to only select related records, it doesn't know how to bind a.id in the nested select.
select afield1, afield2, bfield1
from sometable a left join (
select top 1 id, bfield, aForeignKey
from anothertable
where anothertable.aForeignKey = a.id
order by bfield) b on
b.aForeignKey = a.id
-- Results in the multi-part identifier "a.id" could not be bound
If I hard code values in the nested where clause, the select duration drops from 60 seconds to under five. Anyone have any suggestions on how to join the two tables while not processing every record in the inner table?
EDIT:
I ended up adding
left outer join (
select *, row_number() over (partition by / order by) as rank) b on
b.aforeignkey = a.id and b.rank = 1
went from ~50 seconds to 8 for 22M rows.
Try this:
WITH qry AS
(
SELECT afield1,
afield2,
b.field1 AS bfield1,
ROW_NUMBER() OVER(PARTITION BY a.id ORDER BY field1) rn
FROM sometable a LEFT JOIN anothertable b
ON b.aForeignKey = a.id
)
SELECT *
FROM qry
WHERE rn = 1
Try this
select afield1,
afield2,
bfield1
from sometable a
left join
(select top 1 id, bfield, aForeignKey from anothertable where aForeignKey in(a.id) order by bfield) b on b.aForeignKey = a.id
Not quite sure how to ask this, but I have 2 tables that are related in a 1 to many relationship, I need to select all records in the "1" table that have less than three records in the "many' table.
select b.foreignkey,count(b.foreignkey) as bidcount
from b
where b.foreignkey in (select a.id from a) and bidcount< 3
group by b.foreignkey
this doesn't work at all I know but I am at a loss how to do this.
I need to in the end select all the records from the "a" table based on this criteria. Sorry if that is confusing!
Just using your code, not tested:
SELECT
b.foreignkey,
count(b.foreignkey) as bidcount
FROM
b
WHERE
b.foreignkey IN (SELECT a.id FROM a)
GROUP BY
b.foreignkey
HAVING
count(b.foreignkey) < 3
Try this:
SELECT t1.id,COUNT(t2.parentId)
FROM table1 as t1
INNER JOIN table2 as t2
ON t1.id = t2.parentId
GROUP BY t1.id
HAVING COUNT(t2.parentId) < 3
You didn't mention which version of SQL Server you're using - if you're on SQL Server 2005 or newer, you could use this CTE (Common Table Expression):
;WITH ChildRows AS
(
SELECT A.Id, COUNT(b.Id) AS 'BCount'
FROM
dbo.TableA A
INNER JOIN
dbo.TableB B ON B.TableAId = A.Id
)
SELECT A.*, R.BCount
FROM dbo.TableA A
INNER JOIN ChildRows R ON A.Id = R.Id
The inner SELECT lists the Id columns from TableA and the count of the child rows associated with those (using the INNER JOIN to TableB) - and the outer SELECT just builds on top of that result set and shows all fields from table A (and the count from the B table)
if you want to return all fields of your (1) table in one query, I suggest you consider using CROSS APPLY:
SELECT t1.* FROM table_1 t1
CROSS APPLY (SELECT COUNT(*) cnt FROM Table_Many t2 WHERE t2.fk = t1.pk) a
where a.cnt < 3
in some particular cases, based on your indices and db structure, this query may run 4 times faster than the GROUP BY method
you have posted this question in sql server, I have a answer in oracle database system (don't know whether it will run in sql server as well or not)
this is as follow-
select [desired column list] from
(select b.*, count(*) over (partition by b.foreignkey) c_1
from b
where b.foreignkey in (select a.id from a) )
where c_1 < 3 ;
i hope it should work on sql server as well...
if not please let me update ..