My database name is test, I have a table named HaveGoal.
I am querying this:
SELECT Rel.total
FROM (SELECT H.number, H.teamname, SUM(H.numberofgoals) AS total
FROM HaveGoal H GROUP BY H.number,H.teamname) AS Rel
WHERE Rel.total = (SELECT MAX(Rel.total) FROM Rel)
It gives:ERROR 1146 (42S02): Table 'test.Rel' doesn't exist
It seems that the last subselect cannot reference a nested query defined in the FROM clause.
In this case you have multiple solutions :
Duplicate the first subselect inside the second (and hope that performance will not be too poor)
Define a view to make the nested query available everywhere
As you are looking for the maximum, you could sort data and take only the first line
If you where not on MySQL, you could use the WITH statement
Duplicating will work in any situation :
SELECT Rel.total
FROM (
SELECT H.number, H.teamname, SUM(H.numberofgoals) AS total
FROM HaveGoal H
GROUP BY H.number,H.teamname
) AS Rel
WHERE Rel.total = (
SELECT MAX(Rel2.total)
FROM (
SELECT H.number, H.teamname, SUM(H.numberofgoals) AS total
FROM HaveGoal H
GROUP BY H.number,H.teamname
) AS Rel2
)
Taking the first line after sorting is much shorter, but the MAX is implied :
SELECT Rel.total
FROM (
SELECT H.number, H.teamname, SUM(H.numberofgoals) AS total
FROM HaveGoalTest H
GROUP BY H.number,H.teamname
) AS Rel
ORDER BY total DESC
LIMIT 1
Related
Using ms-sql 2008 r2; am sure this is very straightforward. I am trying to identify where a unique value {ISIN} has been linked to more than 1 Identifier. An example output would be:
isin entity_id
XS0276697439 000BYT-E
XS0276697439 000BYV-E
This is actually an error and I want to look for other instances where there may be more than one entity_id linked to a unique ISIN.
This is my current working but it's obviously not correct:
select isin, entity_id from edm_security_entity_map
where isin is not null
--and isin = ('XS0276697439')
group by isin, entity_id
having COUNT(entity_id) > 1
order by isin asc
Thanks for your help.
Elliot,
I don't have a copy of SQL in front of me right now, so apologies if my syntax isn't spot on.
I'd start by finding the duplicates:
select
x.isin
,count(*)
from edm_security_entity_map as x
group by x.isin
having count(*) > 1
Then join that back to the full table to find where those duplicates come from:
;with DuplicateList as
(
select
x.isin
--,count(*) -- not used elsewhere
from edm_security_entity_map as x
group by x.isin
having count(*) > 1
)
select
map.isin
,map.entity_id
from edm_security_entity_map as map
inner join DuplicateList as dup
on dup.isin = map.isin;
HTH,
Michael
So you're saying that if isin-1 has a row for both entity-1 and entity-2 that's an error but isin-3, say, linked to entity-3 in two separe rows is OK? The ugly-but-readable solution to that is to pre-pend another CTE on the previous solution
;with UniqueValues as
(select distinct
y.isin
,y.entity_id
from edm_security_entity_map as y
)
,DuplicateList as
(
select
x.isin
--,count(*) -- not used elsewhere
from UniqueValues as x
group by x.isin
having count(*) > 1
)
select
map.isin
,map.entity_id
from edm_security_entity_map as map -- or from UniqueValues, depening on your objective.
inner join DuplicateList as dup
on dup.isin = map.isin;
There are better solutions with additional GROUP BY clauses in the final query. If this is going into production I'd be recommending that. Or if your table has a bajillion rows. If you just need to do some analysis the above should suffice, I hope.
I would like to do something like this:
CNT=2;
//[edit]
select avg(price) from (
select first :CNT p.Price
from Price p
order by p.Date desc
);
This does not work, Firebird does not allow :cnt as a parameter to FIRST. I need to average the first CNT newest prices. The number 2 changes so it can not be hard-coded.
This can be broken out into a FOR SELECT loop and break when a count is reached. Is that the best way though? Can this be done in a single SQL statement?
Creating the SQL as a string and running it is not the best fit either. It is important that the database compile my SQL statement.
You don't have to use CTE, you can do it directly:
select avg(price) from (
select first :cnt p.Price
from Price p
order by p.Date desc
);
You can use a CTE (Common Table Expression) (see http://www.firebirdsql.org/refdocs/langrefupd21-select.html#langrefupd21-select-cte) to select data before calculate average.
See example below:
with query1 as (
select first 2 p.Price
from Price p
order by p.Date desc
)
select avg(price) from query1
I'm not sure what this type of query is called so I've been unable to search for it properly. I've got two tables, Table A has about 10,000 rows. Table B has a variable amount of rows.
I want to write a query that gets all of Table A's results but with an added column, the value of that column is a boolean that says whether the result also appears in Table B.
I've written this query which works but is slow, it doesn't use a boolean but rather a count that will be either zero or one. Any suggested improvements are gratefully accepted:
SELECT u.number,u.name,u.deliveryaddress,
(SELECT COUNT(productUserid)
FROM ProductUser
WHERE number = u.number and productid = #ProductId)
AS IsInPromo
FROM Users u
UPDATE
I've run the query with actual execution plan enabled, I'm not sure how to show the results but various costs are:
Nested Loops (left semi join): 29%]
Clustered Index scan (User Table): 41%
Clustered Index Scan (ProductUser table): 29%
NUMBERS
There are 7366 users in the users table and currently 18 rows in the productUser table (although this will change and could be in the thousands)
You can use EXISTS to short circuit after the first row is found rather than COUNT-ing all matching rows.
SQL Server does not have a boolean datatype. The closest equivalent is BIT
SELECT u.number,
u.name,
u.deliveryaddress,
CASE
WHEN EXISTS (SELECT *
FROM ProductUser
WHERE number = u.number
AND productid = #ProductId) THEN CAST(1 AS BIT)
ELSE CAST(0 AS BIT)
END AS IsInPromo
FROM Users u
RE: "I'm not sure what this type of query is called". This will give a plan with a semi join. See Subqueries in CASE Expressions for more about this.
Which management system are you using?
Try this:
SELECT u.number,u.name,u.deliveryaddress,
case when COUNT(p.productUserid) > 0 then 1 else 0 end
FROM Users u
left join ProductUser p on p.number = u.number and productid = #ProductId
group by u.number,u.name,u.deliveryaddress
UPD: this could be faster using mssql
;with fff as
(
select distinct p.number from ProductUser p where p.productid = #ProductId
)
select u.number,u.name,u.deliveryaddress,
case when isnull(f.number, 0) = 0 then 0 else 1 end
from Users u left join fff f on f.number = u.number
Since you seem concerned about performance, this query can perform faster as this will cause index seek on both tables versus an index scan:
SELECT u.number,
u.name,
u.deliveryaddress,
ISNULL(p.number, 0) IsInPromo
FROM Users u
LEFT JOIN ProductUser p ON p.number = u.number
WHERE p.productid = #ProductId
In a table I have records with id's 2,4,5,8. How can I receive a list with values 1,3,6,7. I have tried in this way
SELECT t1.id + 1
FROM table t1
WHERE NOT EXISTS (
SELECT *
FROM table t2
WHERE t2.id = t1.id + 1
)
but it's not working correctly. It doesn't bring all available positions.
Is it possible without another table?
You can get all the missing ID's from a recursive CTE, like this:
with recursive numbers as (
select 1 number
from rdb$database
union all
select number+1
from rdb$database
join numbers on numbers.number < 1024
)
select n.number
from numbers n
where not exists (select 1
from table t
where t.id = n.number)
the number < 1024 condition in my example limit the query to the max 1024 recursion depth. After that, the query will end with an error. If you need more than 1024 consecutive ID's you have either run the query multiple times adjusting the interval of numbers generated or think in a different query that produces consecutive numbers without reaching that level of recursion, which is not too difficult to write.
SELECT DISTINCT a.s_id, select2Result.s_id, select2Result."mNrPhone",
select2Result."dNrPhone"
FROM "Table1" AS a INNER JOIN
(
SELECT b.s_id, c."mNrPhone", c."dNrPhone" FROM "Table2" AS b, "Table3" AS c
WHERE b.a_id = 1001 AND b.s_id = c.s_id
ORDER BY b.last_name) AS select2Result
ON a.a_id = select2Result.student_id
WHERE a.k_id = 11211
It returns:
1001;1001;"";""
1002;1002;"";""
1002;1002;"2342342232123";"2342342"
1003;1003;"";""
1004;1004;"";""
1002 value is repeated twice, but it shouldn't because I used DISTINCT and no other table has an id repeated twice.
You can use DISTINCT ON like this:
SELECT DISTINCT ON (a.s_id)
a.s_id, select2Result.s_id, select2Result."mNrPhone",
select2Result."dNrPhone"
...
But like other persons have told you, the "repeated records" are different really.
The qualifier DISTINCT applies to the entire row, not to the first column in the select-list. Since columns 3 and 4 (mNrPhone and dNrPhone) are different for the two rows with s_id = 1002, the DBMS correctly lists both rows. You have to write your query differently if you only want the s_id = 1002 to appear once, and you have to decide which auxilliary data you want shown.
As an aside, it is strongly recommended that you always use the explicit JOIN notation (which was introduced in SQL-92) in all queries and sub-queries. Do not use the old implicit join notation (which is all that was available in SQL-86 or SQL-89), and especially do not use a mixture of explicit and implicit join notations (where your sub-query uses the implicit join, but the main query uses explicit join). You need to know the old notation so you can understand old queries. You should write new queries in the new notation.
First of all, the query displayed does not work at all, student_id is missing in the sub-query. You use it in the JOIN later.
More interestingly:
Pick a certain row out of a set with DISTINCT
DISTINCT and DISTINCT ON return distinct values by sorting all rows according to the set of columns to be distinct, then it picks the first row from every set. It sorts by all rows for a general DISTINCT and only the specified rows for DISTINCT ON. Here lies the opportunity to pick certain rows out of a set over other.
For instance if you prefer rows with not-empty "mNrPhone" in your example:
SELECT DISTINCT ON (a.s_id) -- sure you didn't want a.a_id?
,a.s_id AS a_s_id -- use aliases to avoid dupe name
,s.s_id AS s_s_id
,s."mNrPhone"
,s."dNrPhone"
FROM "Table1" a
JOIN (
SELECT b.s_id, c."mNrPhone", c."dNrPhone", ??.student_id -- misssing!
FROM "Table2" b
JOIN "Table3" c USING (s_id)
WHERE b.a_id = 1001
-- ORDER BY b.last_name -- pointless, DISTINCT will re-order
) s ON a.a_id = s.student_id
WHERE a.k_id = 11211
ORDER BY a.s_id -- first col must agree with DISTINCT ON, could add DESC though
,("mNrPhone" <> '') DESC -- non-empty first
ORDER BY cannot disagree with DISTINCT on the same query level. To get around this you can either use GROUP BY instead or put the whole query in a sub-query and run another SELECT with ORDER BY on it.
The ORDER BY you had in the sub-query is voided now.
In this particular case, if - as it seems - the dupes come only from the sub-query (you'd have to verify), you could instead:
SELECT a.a_id, s.s_id, s."mNrPhone", s."dNrPhone" -- picking a.a_id over s_id
FROM "Table1" a
JOIN (
SELECT DISTINCT ON (b.s_id)
,b.s_id, c."mNrPhone", c."dNrPhone", ??.student_id -- misssing!
FROM "Table2" b
JOIN "Table3" c USING (s_id)
WHERE b.a_id = 1001
ORDER BY b.s_id, (c."mNrPhone" <> '') DESC -- pick non-empty first
) s ON a.a_id = s.student_id
WHERE a.k_id = 11211
ORDER BY a.a_id -- now you can ORDER BY freely