I'm quite new to SQL Server. Now I came across a query like this:
SELECT country FROM Hovercraft.Orders GROUP BY country ORDER BY ASC
There is no column name given in the order by clause. Is this possible? SSMS says no.
Jörg
It's probably a misprint - you have to specify what you are ordering by; this can be a column name, an expression or the number of a column in the output. It's most likely that the query you have seen was one of the latter, that simply omitted the column number 1 - like so:
SELECT country FROM Hovercraft.Orders GROUP BY country ORDER BY 1 ASC
- so this would order by the contents of the first column of output (ie. country).
I agree with #Mahmoud Gamal. But, also, it's possible to write such hack like this -
SELECT o.country, const_column = 1
FROM Hovercraft.Orders o
GROUP BY o.country
ORDER BY const_column ASC
In this case, sorting will be performed, but rows' order will not be changed.
On MS SQL 2005:
On MS SQL 2012:
This is not possible !..
Order by clause always require column name or column number .
Would you please response me why you want this kind of situation , I think you are working with dynamic query or else please let me know.
As per SQL Standard this not possible.
Thanks.
Related
Actually I am building a Skype like tool wherein I have to show last 10 distinct users who have logged in my web application.
I have maintained a table in sql-server where there is one field called last_active_time. So, my requirement is to sort the table by last_active_time and show all the columns of last 10 distinct users.
There is another field called WWID which uniquely identifies a user.
I am able to find the distinct WWID but not able to select the all the columns of those rows.
I am using below query for finding the distinct wwid :
select distinct(wwid) from(select top 100 * from dbo.rvpvisitors where last_active_time!='' order by last_active_time DESC) as newView;
But how do I find those distinct rows. I want to show how much time they are away fromm web apps using the diff between curr time and last active time.
I am new to sql, may be the question is naive, but struggling to get it right.
If you are using proper data types for your columns you won't need a subquery to get that result, the following query should do the trick
SELECT TOP 10
[wwid]
,MAX([last_active_time]) AS [last_active_time]
FROM [dbo].[rvpvisitors]
WHERE
[last_active_time] != ''
GROUP BY
[wwid]
ORDER BY
[last_active_time] DESC
If the column [last_active_time] is of type varchar/nvarchar (which probably is the case since you check for empty strings in the WHERE statement) you might need to use CAST or CONVERT to treat it as an actual date, and be able to use function like MIN/MAX on it.
In general I would suggest you to use proper data types for your column, if you have dates or timestamps data use the "date" or "datetime2" data types
Edit:
The query aggregates the data based on the column [wwid], and for each returns the maximum [last_active_time].
The result is then sorted and filtered.
In order to add more columns "as-is" (without aggregating them) just add them in the SELECT and GROUP BY sections.
If you need more aggregated columns add them in the SELECT with the appropriate aggregation function (MIN/MAX/SUM/etc)
I suggest you have a look at GROUP BY on W3
To know more about the "execution order" of the instruction you can have a look here
You can solve problem like this by rank ordering the results by a key and finding the last x of those items, this removes duplicates while preserving the key order.
;
WITH RankOrdered AS
(
SELECT
*,
wwidRank = ROW_NUMBER() OVER (PARTITION BY wwid ORDER BY last_active_time DESC )
FROM
dbo.rvpvisitors
where
last_active_time!=''
)
SELECT TOP(10) * FROM RankOrdered WHERE wwidRank = 1
If my understanding is right, below query will give the desired output.
You can have conditions according to your need.
select top 10 distinct wwid from dbo.rvpvisitors order by last_active_time desc
Why are column ordinals legal for ORDER BY but not for GROUP BY? That is, can anyone tell me why this query
SELECT OrgUnitID, COUNT(*) FROM Employee AS e GROUP BY OrgUnitID
cannot be written as
SELECT OrgUnitID, COUNT(*) FROM Employee AS e GROUP BY 1
When it's perfectly legal to write a query like
SELECT OrgUnitID FROM Employee AS e ORDER BY 1
?
I'm really wondering if there's something subtle about the relational calculus, or something, that would prevent the grouping from working right.
The thing is, my example is pretty trivial. It's common that the column that I want to group by is actually a calculation, and having to repeat the exact same calculation in the GROUP BY is (a) annoying and (b) makes errors during maintenance much more likely. Here's a simple example:
SELECT DATEPART(YEAR,LastSeenOn), COUNT(*)
FROM Employee AS e
GROUP BY DATEPART(YEAR,LastSeenOn)
I would think that SQL's rule of normalize to only represent data once in the database ought to extend to code as well. I'd want to only right that calculation expression once (in the SELECT column list), and be able to refer to it by ordinal in the GROUP BY.
Clarification: I'm specifically working on SQL Server 2008, but I wonder about an overall answer nonetheless.
One of the reasons is because ORDER BY is the last thing that runs in a SQL Query, here is the order of operations
FROM clause
WHERE clause
GROUP BY clause
HAVING clause
SELECT clause
ORDER BY clause
so once you have the columns from the SELECT clause you can use ordinal positioning
EDIT, added this based on the comment
Take this for example
create table test (a int, b int)
insert test values(1,2)
go
The query below will parse without a problem, it won't run
select a as b, b as a
from test
order by 6
here is the error
Msg 108, Level 16, State 1, Line 3
The ORDER BY position number 6 is out of range of the number of items in the select list.
This also parses fine
select a as b, b as a
from test
group by 1
But it blows up with this error
Msg 164, Level 15, State 1, Line 3
Each GROUP BY expression must contain at least one column that is not an outer reference.
There is a lot of elementary inconsistencies in SQL, and use of scalars is one of them. For example, anyone might expect
select * from countries
order by 1
and
select * from countries
order by 1.00001
to be a similar queries (the difference between the two can be made infinitesimally small, after all), which are not.
I'm not sure if the standard specifies if it is valid, but I believe it is implementation-dependent. I just tried your first example with one SQL engine, and it worked fine.
use aliasses :
SELECT DATEPART(YEAR,LastSeenOn) as 'seen_year', COUNT(*) as 'count'
FROM Employee AS e
GROUP BY 'seen_year'
** EDIT **
if GROUP BY alias is not allowed for you, here's a solution / workaround:
SELECT seen_year
, COUNT(*) AS Total
FROM (
SELECT DATEPART(YEAR,LastSeenOn) as seen_year, *
FROM Employee AS e
) AS inline_view
GROUP
BY seen_year
databases that don't support this basically are choosing not to. understand the order of the processing of the various steps, but it is very easy (as many databases have shown) to parse the sql, understand it, and apply the translation for you. Where its really a pain is when a column is a long case statement. having to repeat that in the group by clause is super annoying. yes, you can do the nested query work around as someone demonstrated above, but at this point it is just lack of care about your users to not support group by column numbers.
I'm using SQL Server 2012 and I was wondering if there is a way to select, for example, the third result from a query. I have looked into LIMIT and OFFSET but I'm not 100% sure if it applies to SQL Server, however I've been told that there is something to do what I want in SQL Server 2012.
SELECT *
FROM YourTable
ORDER BY OrderingColumn ASC
OFFSET 2 ROWS /*Skip first 2 rows*/
FETCH NEXT 1 ROWS ONLY
Note: You cannot use OFFSET ... FETCH without doing an ORDER BY first
I would recommend
select * from table ORDER BY OrderingColumn ASC LIMIT n,1
This is a quirk of limit where if you give it a range, it only returns that range. It works in MySQL too.
Can’t you just select the second index? This is the way i would take say the third post in my table.
//index 3
$index3 = DB::query(‘SELECT * from posts’)[2];
Then you will have an array that is ready to go for you.
I am using where in condition in SQL Server. I want to get result without order, because I gave a list into the 'where in' condition.
For example
select * from blabla where column in ('03.01.KO61.01410',
'03.02.A081.15002',
'03.02.A081.15016',
'03.02.A081.15003',
'02.03.A081.57105')
How can I do?
If you want the rows returned such that they're in the same order as the items in your IN, you need to find some way to specify that in an ORDER BY clause - the only way to get SQL Server to define an order. E.g.:
select * from blabla where column in ('03.01.KO61.01410',
'03.02.A081.15002',
'03.02.A081.15016',
'03.02.A081.15003',
'02.03.A081.57105')
order by
CASE column
when '03.01.KO61.01410' then 1
when '03.02.A081.15002' then 2
when '03.02.A081.15016' then 3
when '03.02.A081.15003' then 4
when '02.03.A081.57105' then 5
end
Due to my experience, SQL Server randomly order the result set for WHERE-IN Clause if you does not specify how to order it.
So, if you want to order by your WHERE-IN conditions, you must define some data item to order it as you passed. Otherwise, SQL Server will randomly order your resultset.
You're already doing it - if you don't explicitly specify an order by using ORDER BY, then there is no implied order.
If you want to totally randomize the output, you could add an ORDER BY NEWID() clause:
SELECT (list of columns)
FROM dbo.blabla
WHERE column IN ('03.01.KO61.01410', '03.02.A081.15002',
'03.02.A081.15016', '03.02.A081.15003', '02.03.A081.57105')
ORDER BY NEWID()
If you have an autoincrement id in your table, use it in an order clause. And if you don't, consider adding one...
Try this:
CREATE TYPE varchar20_list_type AS TABLE (
id INT IDENTITY PRIMARY KEY,
val VARCHAR(20) NOT NULL UNIQUE
)
DECLARE #mylist varchar20_list_type
INSERT #mylist (val) VALUES
('03.01.KO61.01410'),
('03.02.A081.15002'),
('03.02.A081.15016'),
('03.02.A081.15003'),
('02.03.A081.57105')
SELECT
*
FROM
blabla
JOIN #mylist AS t
ON
blabla.col = t.val
ORDER BY
t.id
More information from http://www.sommarskog.se/arrays-in-sql-2008.html
By the way, this can be easily done in PostgreSQL with VALUES: http://www.postgresql.org/docs/9.0/static/queries-values.html
I will re-write my doubt to be more easy to understand.
I have one table named SeqNumbers that have only one column of data named PossibleNumbers, that has value from 1 to 10.000.
Then I have another Table named Terminals and one of the columns have the serial numbers of the terminals. What I want is get all the SerialNumbers that not exists in the Terminals table from 1 to 10.000.
I've created the SeqNumbers table only to do this... maybe there's another solution without using it... that's fine to me.
The query I have is:
SELECT PossibleNumbers from SeqNumbers
Where PossibleNumbers NOT IN (SELECT SerialNumbers from Terminals)**
Basically I want to list ALL serial numbers of terminals that doesn't exists in the database.
This Query works fine I think... but the problem is that I don't want all results in a single column.. I want these results displayed in 4 or 5 columns.
For my purpose I can only use the results from the query like that. I cannot use programmatically methods to do that.
Hope this is more clear now... Thanks for all the help...
select x, x+1000 from tablename
Will that do it for you?
If I'm reading this right, you'd probably have to do a self join; something like:
SELECT
LeftValues.ColA,
RightValues.ColA AS ColB
FROM YourTable LeftValues
LEFT JOIN YourTable RightValues ON LeftValues.ColA = RightValues.ColA - 1000
WHERE LeftValues.ColA < 1000
Note: Use the JOIN that makes sense for you (left if you are willing to accept NULLs in ColB, inner if you only want them where both values exist)
You can use a scripting language to parse the MySQL results to format it anyway you like. Are you using PHP to access the database? If so, let me know and I can cook one up for you.
I just saw your new updated question. In this case the order of the columns will be ordered by your SELECT statement and you can also sort too. Here is an example:
SELECT Column1, Column2 FROM my_table ORDER BY Column1, Column2 ASC