This query is MySql
select
a.id,
a.name,
a.vehicle,
a.amt,
a.date
(select id
from tbl1
where date < a.date and vehicle = a.vehicle
LIMIT 0,1) as prv
FROM
root_tbl a
WHERE
amt <> 0
I need this query in SQL Server. Could you please assist me.
LIMIT is not supported by SQL Server.
If you want to get the first x rows of a table, you have to use TOP, as in SELECT TOP (10) * FROM tbl1.
To do an offset equivalent, there are a few techniques, such as a subquery adding ROW_NUMBER() to the result set, and in the parent query filtering by for the desired offset.
SELECT *
FROM (
SELECT
id,
ROW_NUMBER() OVER (ORDER BY id) AS RowNum
FROM tbl1
) T
WHERE RowNum BETWEEN 51 AND 75 -- Similar to LIMIT 50,25
For your specific query, you seem to just need a TOP to be most efficient, so the following should work for your query.
select
a.id,
a.name,
a.vehicle,
a.amt,
a.date
(select top (1) id from tbl1 where date < a.date and vehicle=a.vehicle)as prv
FROM tbl1 a
Related
Actually I'm working with the following table fsa_areas:
Note that each area has a responsible
Now, what I need to do, is to order the same table as following:
Note that now the results are ordered by the the responsible with more areas and at the end the responsible with less areas.
Is there a way to order them in that way?
You can use a COUNT subquery in the ORDER BY clause:
select a.*
from fsa_areas a
order by (select count(*) from fsa_areas a1 where a1.Responsible = a.Responsible) desc
Another way is to get the count in a derived table and join the base table to it
select a.*
from (
select Responsible, count(*) as cnt
from fsa_areas
group by Responsible
) r
join fsa_areas a using(Responsible)
order by r.cnt desc
In MySQL 8 you can use COUNT() as window function:
select *, count(*) over (partition by Responsible) as cnt
from fsa_areas
order by cnt desc
I have a query SELECT * FROM grades WHERE userid = 4123;
I want to limit this query
I have a query SELECT * FROM grades WHERE userid = 4123 LIMIT(2);
This works great but if I want this limit to be dynamic from another query.
SELECT COUNT(id) FROM count_table WHERE course = 131;
doing this gives me a syntax error
SELECT * FROM grades WHERE userid = 4123 LIMIT (SELECT COUNT(id) FROM count_table WHERE course = 131);
if this is not possible at all, then is there an alternative way to achieve this?
please help.!
You can do it in MySQL 8.x using the ROW_NUMBER() function.
Assuming you order the rows by some column (I guessed the column ID... change it as needed), you can do:
select
g.*
from (
select
*,
row_number() over(order by id) as rn -- change ordering as needed
from grades
) g
join (
SELECT COUNT(id) as cnt FROM count_table WHERE course = 131
) c on g.rn <= c.cnt
I have the following query working
SELECT newTable.Score, COUNT(1) AS Total, COUNT(1) / t.count * 100 AS `Frequency`
FROM mytable newTable
CROSS JOIN (SELECT COUNT(1) AS count FROM mytable) t
GROUP BY newTable.Score
ORDER BY Frequency DESC
However, two things I don't understand from the MySQL docs:
1) I don't understand why there isn't a comma, or a join type, specified in the from clause.
Reading the MySQL docs, this seems necessary.
2) What does the 't' represent in the CROSS JOIN clause?
Any advice appreciated.
The t is the same as the newTable - it is an alias name for the table and the temporary table that the subquery builds.
It is easier to read when the optional as keyword is used
SELECT newTable.Score, COUNT(1) AS Total, COUNT(1) / t.count * 100 AS `Frequency`
FROM mytable as newTable
CROSS JOIN (SELECT COUNT(1) AS count FROM mytable) as t
GROUP BY newTable.Score
ORDER BY Frequency DESC
An alias name replaces the original name of the table with a new one to be used in your query. And you need to give subqueries a name to refer to them in your query too.
Here is my data. I want to take 6 rows, but I want all HeadlineCategoryId's to be unique in my result list. If I select the top 6 I would take 2 rows from HeadlineCategoryID 20 (6,2). Do you have any suggestions about it?
SELECT a.*
FROM tableName a
INNER JOIN
(
SELECT HeadlineCategoryID, MAX(Creation) max_date
FROM TableName
GROUP BY HeadlineCategoryID
) b ON a.HeadlineCategoryID = b.HeadlineCategoryID AND
a.Creation = b.max_date
ORDER BY a.Creation DESC -- << specify here how are you going to sort
LIMIT 6 -- the records you want to get
UPDATE 1
SELECT a.*
FROM tableName a
INNER JOIN
(
SELECT HeadlineCategoryID, MAX(NewsID) max_id
FROM TableName
GROUP BY HeadlineCategoryID
) b ON a.HeadlineCategoryID = b.HeadlineCategoryID AND
a.NewsID = b.max_id
ORDER BY a.Creation DESC -- << specify here how are you going to sort
LIMIT 6 -- the records you want to get
It looks like you want the six most recent records, but unique by HeadlineCategoryId. If so, this will work:
select top 6 NewsId, Creation, HeadlineCategoryId
from (select t.*,
row_number() over (partition by HeadlineCategoryId order by Creation desc) as seqnum
from t
) t
where seqnum = 1
As a note . . . This question originally indicated that it was using SQL Server, not MySQL. The solution in MySQL is not as simple. Here is one method with not exists:
select NewsId, Creation, HeadlineCategoryId
from t
where not exists (select 1
from t t2
where t2.HeadlineCategoryId = t.HeadlineCategoryId and
t2.id < t.id)
limit 6
The not exists portion is saying "where there is no other record with a larger id for a given headline category".
Is it possible to pull 2 results from a sub query in a sql statement?
I have:
"SELECT
(SELECT bid FROM auction_bids WHERE itemID=a.id ORDER BY bid DESC LIMIT 1) as topbid,
a.* FROM auction_items a ORDER BY a.date DESC LIMIT 15"
The part where it returns the topbid, i'd also like it to pull not only bid (as topbid) but also date (as topdate) as well. How can I do that? Do I need another sub query or can it pull both in one?
Dependent subquery (depending on some values outside, like a.id in your case) is not a very efficient way to find maximum values in subsets.
Instead use a subquery with GROUP BY:
SELECT b.topbid, b.topdate, a.*
FROM auction_items a
LEFT JOIN
( SELECT itemID, MAX(bid) as topbid, MAX(date) as topdate
FROM auction_bids
GROUP BY itemID ) b
ON a.id = b.itemID
ORDER BY a.date DESC
LIMIT 15