Related
I have pictures in a database which I now need to extract. The image column is of type varbinary(max).
I tried several examples using either a JOIN or subquery to no avail. The query developed would work if it wasn't for the image. Using DISTINCT and MAX(date) still can't eliminnate the older image. Many IDs have multiple pictures. Using the Max(Date) would extract the most recent date, but adding in the picture eliminates all the filtering.
The query looks like this:
SELECT DISTINCT ID, Image, DateModified, GETDate()
FROM images
WHERE
TYPE = 'B'
ID Image DateMod Type
1 0x789 01-02-2014 B
1 0x791 11-12-2015 B <-- this is a tgt record
2 0x675 12-01-2015 A
5 0x324 06-26-2015 B <-- this is a tgt record
If I use MAX(DateModified), that forces a GROUP BY and it still doesn't eliminate the older images. I need the newest Type 'B' image for each ID. I am working on SQL Server 2012.
What I need for output is
image, ID, DateModified, TodaysDate (GetDate)
Pretty sure you want something like this.
with SortedResults as
(
select ID
, Image
, DateMod
, Type
, ROW_NUMBER() over (partition by ID order by DateMod desc) as RowNum
from images
where Type = 'B'
)
select ID
, Image
, DateMod
, GetDate()
from SortedResults
where RowNum = 1
Try following query
SELECT
I.[Image],
I.DateMod,
GetDate()
FROM
(
SELECT
ID,
MAX(DateModified) AS DateModified
FROM
images
WHERE
[TYPE] = 'B'
GROUP BY
ID
) A INNER JOIN
images I ON A.ID = I.ID AND A.DateModified = I.DateModified
The problem is likely twofold:
1) You are confusing the logical order of the clauses used in SQL Server.
2) Your DISTINCT is the culprit.
I suggest you study and memorize the Logical order of SQL Clauses so that you understand logically how SQL Server is reading your prescribed query. For simplicity, start with the Classic list, which is used in many places.
Classic Complete
FROM | FROM
WHERE | ON
GROUP BY | JOIN
HAVING | WHERE
SELECT | GROUP BY
ORDER BY | WITH CUBE, WITH ROLLUP
| HAVING
| SELECT
| DISTINCT
| ORDER BY
| TOP
Already we can see why your query is returning the results wrong, since SQL Server is not smashing the column sets together but rather smashing distinct rows across your columns.
Your example list:
ID Image DateMod Type
1 0x789 01-02-2014 B
1 0x791 11-12-2015 B <-- this is a tgt record
2 0x675 12-01-2015 A
5 0x324 06-26-2015 B <-- this is a tgt record
Has unique rows and therefore returns all of the records. Clearly, DISTINCT is the problem.
One solution is to keep your predicate the same and use the GROUP BY clause to smash sets of columns and use the MAX() aggregate function to return the largest value.
;WITH C AS
( SELECT ID
, MAX(DateMod) AS DateModified
, CONVERT(VARCHAR(10), GETDATE(), 110) AS [Current_Time]
FROM #Images
WHERE Type = 'B'
GROUP BY ID, Type)
SELECT C.ID, B.Image, C.DateModified, C.[Current_Time]
FROM C
LEFT OUTER JOIN (SELECT ID, DateMod, Image FROM #Images) B ON C.ID = B.ID
AND C.DateModified = B.DateMod
-- results
ID Image DateModified Current_Time
1 0x3078373931 11-12-2015 07-16-2016
5 0x3078333234 06-26-2015 07-16-2016
I have a strange behaviour with a SQL Server query/function.
I have a table with 3 columns (actually there are more columns, but these 3 are relevant for this task). The columns are FileId, UserId and TimeCreated. It is possible, that one user can create the same FileId multiple times, and I want to know, which was the newest created file.
I am doing it with this WHERE clause:
WHERE TimeCreated IN (SELECT MAX(TimeCreated)
FROM table
GROUP BY FileId, UserId)
In my opinion this should be correct, but for some groups, it returns multiple rows, even if the TimeCreated is different.
Here is one result as an example:
TimeCreated | UserId | FileId
------------------------------------------------------
2016-01-18 00:00:00.000 | UserA | FileA
2016-01-18 06:00:00:000 | UserA | FileA
But it should only return the row with '2016-01-18 06:00:00:000' as TimeCreated value.
I don't understand what is going wrong, because there are a lot more entries, which have UserA (as UserId) AND FileA (as FileId) but different TimeCreated values but it only returns this two rows (so in some way, it is quite working) and like I said, for some groups it is ok, but sometimes it returns two rows with the same UserId and FileId but different TimeCreated values. And when this happens it's always two rows and not more.
The TimeCreated is a DateTimeOffset(7), UserId is a string as well as FileId. Maybe this is important to know...
Does someone have an explanation why this is happening?
You should use this syntax instead:
;WITH CTE as
(
SELECT
*,
row_number() over (partition by FileId, UserId ORDER BY TimeCreated DESC)rn
FROM <table>
)
SELECT * FROM CTE
WHERE rn = 1
What's going wrong is that your inner select returns more than one value. It returns the maximum of TimeCreated for each combination FileId and UserID in the table.
One way to solve it is this:
...
FROM table t1
INNER JOIN
(
select FileId, UserId, max(TimeCreated) as maxTimeCreated
from table
group by FileId, UserId)
)
t2 ON t1.TimeCreated = t2.maxTimeCreatedAND t1.UserId = t2.USerId AND T1.FileId = t2.FileId
However, if you post your table structure and desired results, someone might show you a better way.
You are not joining the subquery by UserId, so your lower TimeCreated may correspond to another user file.
from table t1
where TimeCreated = (select max(TimeCreated)
from table
where table.UserId = t1.UserId
and table.FileId = t1.FileId )
I have a TSQL query that I am trying to group data on. The table contains records of users and the access keys they hold such as site admin, moderator etc. The PK is on User and access key because a user can exist multiple times with different keys.
I am now trying to display a table of all users and in one column, all of the keys that user holds.
If bob had three separate records for his three separate access keys, result should only have One record for bob with all three of is access levels.
SELECT A.[FirstName],
A.[LastName],
A.[ntid],
A.[qid],
C.FirstName AS addedFirstName,
C.LastName AS addedLastName,
C.NTID AS addedNTID,
CONVERT(VARCHAR(100), p.TIMESTAMP, 101) AS timestamp,
(
SELECT k.accessKey,
k.keyDescription
FROM TFS_AdhocKeys AS k
WHERE p.accessKey = k.accessKey
FOR XML PATH ('key'), TYPE, ELEMENTS, ROOT ('keys')
)
FROM TFS_AdhocPermissions AS p
LEFT OUTER JOIN dbo.EmployeeTable as A
ON p.QID = A.QID
LEFT OUTER JOIN dbo.EmployeeTable AS C
ON p.addedBy = C.QID
GROUP BY a.qid
FOR XML PATH ('data'), TYPE, ELEMENTS, ROOT ('root');
END
I am trying to group the data by a.qid but its forcing me to group on every column in the select which will then not be unique so it will contain the duplicates.
Whats another approach to handle this?
Currently:
UserID | accessKey
123 | admin
123 | moderator
Desired:
UserID | accessKey
123 | admin
moderator
Recently, I was working on something and had a similar problem. Like your query, I had an inner 'for xml' with joins in the outer 'for xml'. It turned out it worked better if the joins were in the inner 'for xml'. The code is pasted below. I hope this helps.
Select
(Select Institution.Name, Institution.Id
, (Select Course.Courses_Id, Course.Expires, Course.Name
From
(Select Course.Courses_Id, Course.Expires, Courses.Name
From Institutions Course Course Join Courses On Course.Courses_Id = Courses.Id
Where Course.Institutions_Id = 31) As Course
For Xml Auto, Type, Elements) As Courses
From Institutions Institution
For Xml Auto, Elements, Root('Institutions') )
As I don't have the definitions for the other tables you have I just make a sample test data and you can follow this to answer yours.
Create statement
CREATE TABLE #test(UserId INT, AccessLevel VARCHAR(20))
Insert sample data
INSERT INTO #test VALUES(123, 'admin')
,(123, 'moderator')
,(123, 'registered')
,(124, 'moderator')
,(124, 'registered')
,(125, 'admin')
By using ROW_NUMBER() you can achieve what you need
;WITH C AS(
SELECT ROW_NUMBER() OVER(PARTITION BY UserId ORDER BY UserId) As Rn
,UserId
,AccessLevel
FROM #test
)
SELECT CASE Rn
WHEN 1 THEN UserId
ELSE NULL
END AS UserId
,AccessLevel
FROM C
Output
UserId AccessLevel
------ -----------
123 admin
NULL moderator
NULL registered
124 moderator
NULL registered
125 admin
I need to get some items from database with top three comments for each item.
Now I have two stored procedures GetAllItems and GetTopThreeeCommentsByItemId.
In application I get 100 items and then in foreach loop I call GetTopThreeeCommentsByItemId procedure to get top three comments.
I know that this is bad from performance standpoint.
Is there some technique that allows to get this with one query?
I can use OUTER APPLY to get one top comment (if any) but I don't know how to get three.
Items {ItemId, Title, Description, Price etc.}
Comments {CommentId, ItemId etc.}
Sample data that I want to get
Item_1
-- comment_1
-- comment_2
-- comment_3
Item_2
-- comment_4
-- comment_5
One approach would be to use a CTE (Common Table Expression) if you're on SQL Server 2005 and newer (you aren't specific enough in that regard).
With this CTE, you can partition your data by some criteria - i.e. your ItemId - and have SQL Server number all your rows starting at 1 for each of those "partitions", ordered by some criteria.
So try something like this:
;WITH ItemsAndComments AS
(
SELECT
i.ItemId, i.Title, i.Description, i.Price,
c.CommentId, c.CommentText,
ROW_NUMBER() OVER(PARTITION BY i.ItemId ORDER BY c.CommentId) AS 'RowNum'
FROM
dbo.Items i
LEFT OUTER JOIN
dbo.Comments c ON c.ItemId = i.ItemId
WHERE
......
)
SELECT
ItemId, Title, Description, Price,
CommentId, CommentText
FROM
ItemsAndComments
WHERE
RowNum <= 3
Here, I am selecting up to three entries (i.e. comments) for each "partition" (i.e. for each item) - ordered by the CommentId.
Does that approach what you're looking for??
You can write a single stored procedure which calls GetAllItems and GetTopThreeeCommentsByItemId, takes results in temp tables and join those tables to produce the single resultset you need.
If you do not have a chance to use a stored procedure, you can still do the same by running a single SQL script from data access tier, which calls GetAllItems and GetTopThreeeCommentsByItemId and takes results into temp tables and join them later to return a single resultset.
This gets two elder brother using OUTER APPLY:
select m.*, elder.*
from Member m
outer apply
(
select top 2 ElderBirthDate = x.BirthDate, ElderFirstname = x.Firstname
from Member x
where x.BirthDate < m.BirthDate
order by x.BirthDate desc
) as elder
order by m.BirthDate, elder.ElderBirthDate desc
Source data:
create table Member
(
Firstname varchar(20) not null,
Lastname varchar(20) not null,
BirthDate date not null unique
);
insert into Member(Firstname,Lastname,Birthdate) values
('John','Lennon','Oct 9, 1940'),
('Paul','McCartney','June 8, 1942'),
('George','Harrison','February 25, 1943'),
('Ringo','Starr','July 7, 1940');
Output:
Firstname Lastname BirthDate ElderBirthDate ElderFirstname
-------------------- -------------------- ---------- -------------- --------------------
Ringo Starr 1940-07-07 NULL NULL
John Lennon 1940-10-09 1940-07-07 Ringo
Paul McCartney 1942-06-08 1940-10-09 John
Paul McCartney 1942-06-08 1940-07-07 Ringo
George Harrison 1943-02-25 1942-06-08 Paul
George Harrison 1943-02-25 1940-10-09 John
(6 row(s) affected)
Live test: http://www.sqlfiddle.com/#!3/19a63/2
marc's answer is better, just use OUTER APPLY if you need to query "near" entities (e.g. geospatial, elder brothers, nearest date to due date, etc) to the main entity.
Outer apply walkthrough: http://www.ienablemuch.com/2012/04/outer-apply-walkthrough.html
You might need DENSE_RANK instead of ROW_NUMBER/RANK though, as the criteria of a comment being a top could yield ties. TOP 1 could yield more than one, TOP 3 could yield more than three too. Example of that scenario(DENSE_RANK walkthrough): http://www.anicehumble.com/2012/03/postgresql-denserank.html
Its better that you select the statement by using the row_number statement and select the top 3 alone
select a.* from
(
Select *,row_number() over(partition by column)[dup]
) as a
where dup<=3
I want to learn how to combine two db tables which have no fields in common. I've checked UNION but MSDN says :
The following are basic rules for combining the result sets of two queries by using UNION:
The number and the order of the columns must be the same in all queries.
The data types must be compatible.
But I have no fields in common at all. All I want is to combine them in one table like a view.
So what should I do?
There are a number of ways to do this, depending on what you really want. With no common columns, you need to decide whether you want to introduce a common column or get the product.
Let's say you have the two tables:
parts: custs:
+----+----------+ +-----+------+
| id | desc | | id | name |
+----+----------+ +-----+------+
| 1 | Sprocket | | 100 | Bob |
| 2 | Flange | | 101 | Paul |
+----+----------+ +-----+------+
Forget the actual columns since you'd most likely have a customer/order/part relationship in this case; I've just used those columns to illustrate the ways to do it.
A cartesian product will match every row in the first table with every row in the second:
> select * from parts, custs;
id desc id name
-- ---- --- ----
1 Sprocket 101 Bob
1 Sprocket 102 Paul
2 Flange 101 Bob
2 Flange 102 Paul
That's probably not what you want since 1000 parts and 100 customers would result in 100,000 rows with lots of duplicated information.
Alternatively, you can use a union to just output the data, though not side-by-side (you'll need to make sure column types are compatible between the two selects, either by making the table columns compatible or coercing them in the select):
> select id as pid, desc, null as cid, null as name from parts
union
select null as pid, null as desc, id as cid, name from custs;
pid desc cid name
--- ---- --- ----
101 Bob
102 Paul
1 Sprocket
2 Flange
In some databases, you can use a rowid/rownum column or pseudo-column to match records side-by-side, such as:
id desc id name
-- ---- --- ----
1 Sprocket 101 Bob
2 Flange 101 Bob
The code would be something like:
select a.id, a.desc, b.id, b.name
from parts a, custs b
where a.rownum = b.rownum;
It's still like a cartesian product but the where clause limits how the rows are combined to form the results (so not a cartesian product at all, really).
I haven't tested that SQL for this since it's one of the limitations of my DBMS of choice, and rightly so, I don't believe it's ever needed in a properly thought-out schema. Since SQL doesn't guarantee the order in which it produces data, the matching can change every time you do the query unless you have a specific relationship or order by clause.
I think the ideal thing to do would be to add a column to both tables specifying what the relationship is. If there's no real relationship, then you probably have no business in trying to put them side-by-side with SQL.
If you just want them displayed side-by-side in a report or on a web page (two examples), the right tool to do that is whatever generates your report or web page, coupled with two independent SQL queries to get the two unrelated tables. For example, a two-column grid in BIRT (or Crystal or Jasper) each with a separate data table, or a HTML two column table (or CSS) each with a separate data table.
This is a very strange request, and almost certainly something you'd never want to do in a real-world application, but from a purely academic standpoint it's an interesting challenge. With SQL Server 2005 you could use common table expressions and the row_number() functions and join on that:
with OrderedFoos as (
select row_number() over (order by FooName) RowNum, *
from Foos (nolock)
),
OrderedBars as (
select row_number() over (order by BarName) RowNum, *
from Bars (nolock)
)
select *
from OrderedFoos f
full outer join OrderedBars u on u.RowNum = f.RowNum
This works, but it's supremely silly and I offer it only as a "community wiki" answer because I really wouldn't recommend it.
SELECT *
FROM table1, table2
This will join every row in table1 with table2 (the Cartesian product) returning all columns.
select
status_id,
status,
null as path,
null as Description
from
zmw_t_status
union
select
null,
null,
path as cid,
Description from zmw_t_path;
try:
select * from table 1 left join table2 as t on 1 = 1;
This will bring all the columns from both the table.
If the tables have no common fields then there is no way to combine the data in any meaningful view. You would more likely end up with a view that contains duplicated data from both tables.
To get a meaningful/useful view of the two tables, you normally need to determine an identifying field from each table that can then be used in the ON clause in a JOIN.
THen in your view:
SELECT T1.*, T2.* FROM T1 JOIN T2 ON T1.IDFIELD1 = T2.IDFIELD2
You mention no fields are "common", but although the identifying fields may not have the same name or even be the same data type, you could use the convert / cast functions to join them in some way.
why don't you use simple approach
SELECT distinct *
FROM
SUPPLIER full join
CUSTOMER on (
CUSTOMER.OID = SUPPLIER.OID
)
It gives you all columns from both tables and returns all records from customer and supplier if Customer has 3 records and supplier has 2 then supplier'll show NULL in all columns
Select
DISTINCT t1.col,t2col
From table1 t1, table2 t2
OR
Select
DISTINCT t1.col,t2col
From table1 t1
cross JOIN table2 t2
if its hug data , its take long time ..
SELECT t1.col table1col, t2.col table2col
FROM table1 t1
JOIN table2 t2 on t1.table1Id = x and t2.table2Id = y
Joining Non-Related Tables
Demo SQL Script
IF OBJECT_ID('Tempdb..#T1') IS NOT NULL DROP TABLE #T1;
CREATE TABLE #T1 (T1_Name VARCHAR(75));
INSERT INTO #T1 (T1_Name) VALUES ('Animal'),('Bat'),('Cat'),('Duet');
SELECT * FROM #T1;
IF OBJECT_ID('Tempdb..#T2') IS NOT NULL DROP TABLE #T2;
CREATE TABLE #T2 (T2_Class VARCHAR(10));
INSERT INTO #T2 (T2_Class) VALUES ('Z'),('T'),('H');
SELECT * FROM #T2;
To Join Non-Related Tables , we are going to introduce one common joining column of Serial Numbers like below.
SQL Script
SELECT T1.T1_Name,ISNULL(T2.T2_Class,'') AS T2_Class FROM
( SELECT T1_Name,ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) AS S_NO FROM #T1) T1
LEFT JOIN
( SELECT T2_Class,ROW_NUMBER() OVER(ORDER BY (SELECT NULL)) AS S_NO FROM #T2) T2
ON t1.S_NO=T2.S_NO;
select * from this_table;
select distinct person from this_table
union select address as location from that_table
drop wrong_table from this_database;
Very hard when you have to do this with three select statments
I tried all proposed techniques up there but it's in-vain
Please see below script. please advice if you have alternative solution
select distinct x.best_Achiver_ever,y.Today_best_Achiver ,z.Most_Violator from
(SELECT Top(4) ROW_NUMBER() over (order by tl.username) AS conj, tl.
[username] + '-->' + str(count(*)) as best_Achiver_ever
FROM[TiketFollowup].[dbo].N_FCR_Tikect_Log_Archive tl
group by tl.username
order by count(*) desc) x
left outer join
(SELECT
Top(4) ROW_NUMBER() over (order by tl.username) as conj, tl.[username] + '-->' + str(count(*)) as Today_best_Achiver
FROM[TiketFollowup].[dbo].[N_FCR_Tikect_Log] tl
where convert(date, tl.stamp, 121) = convert(date,GETDATE(),121)
group by tl.username
order by count(*) desc) y
on x.conj=y.conj
left outer join
(
select ROW_NUMBER() over (order by count(*)) as conj,username+ '--> ' + str( count(dbo.IsViolated(stamp))) as Most_Violator from N_FCR_Ticket
where dbo.IsViolated(stamp) = 'violated' and convert(date,stamp, 121) < convert(date,GETDATE(),121)
group by username
order by count(*) desc) z
on x.conj = z.conj
Please try this query:
Combine two tables that have no common columns:
SELECT *
FROM table1
UNION
SELECT *
FROM table2
ORDER BY orderby ASC