Very new to SQL programming so apologies if my terminology is a little off.
I need some help combining a few tables, however I'm worried that it's not even possible!! (but what do I know)
So I have 1 table that is just a list of feeds. A, B, C, D etc (15 rows in total) and each feed has other information attached to it such as Full name, location etc etc. I am only interested in the Feed column.
Each feed then has a corresponding data table which contains a list of records. Eg Feed A data is contained in TableA, Feed B data is contains in TableB and so on.
Basically what I need is a combined table that shows the list of Feeds in the 1st Column ( So A, B, C, D…..) and then a second column which counts the records from each separate data table corresponding to that feed.
So the end result would look something like this:
Feed No of Records
A 4 (from TableA)
B 7 (from TableB)
C 8 (from TableC)
D 1 (from TableD)
Possible?
Any help on sql code would be much appreciated.
Thanks
Related
In SQL Server what is the correct way to retrieve data that is in alphabetical order from the same table on 2 different shards?
Right now on the db I am working on there is a table that exists on 2 different shards. I need to be able to select the data from each table in alphabetical order in batches of 5. So for example.
In Shard1 we have a table with 6 items of data
A,
A,
A,
A,
A,
A
In Shard2 we have a table with 4 items of data
A2,
B2,
C2,
D2,
When I run my query the first time I need to return
A,
A,
A,
A,
A
When I run it the next time it should return
A,
A2,
B2,
C2,
D2
I have been looking through documentation but unclear what to do. The reason is that this seems not possible because there would have to be some sort of middle component that would have to keep track of the alphabetical order of each table in separate databases. I know it is easy to execute operations that alphabetize on 1 table in 1 database, but across databases and tables seems not possible. What is the correct way to do this with sql server? Or this even possible?
It's not fully clear what you're asking about since sharding isn't a concrete feature in SQL Server.
That being said, let's assume you have two separate SQL Server instances, with the same table, and you've setup a Linked Server between them. You can combine the two sets of data with a UNION or UNION ALL (depending on if you want to remove or keep duplicates in the dataset, respectively) within a subquery and then order them alphabetically like so:
SELECT TOP 5 -- Top 5 alphabetically
ItemId
FROM
(
SELECT ItemId
FROM dbo.Items -- Local instance's copy of the table
UNION -- Removing duplicates (as per your example)
SELECT ItemId
FROM LinkedServerName.DatabaseName.dbo.Items -- Remote instance's copy of the table
) AS Items
ORDER BY ItemId
I am a bit stuck and would appreciate some help.
I have the following data structure as shown in the image below.
So I want to link C and D basically apply the list to list. And if possible how would I do this in ef core. I did try a different query
SELECT * FROM A a
JOIN B b on a.PKA= B.PKB
But I only get the multiplication of list every record from table B got a pair for every record of table A. One more question if records in table C don't have the same number of record in table D it values should be null
I really need to know the query to display another field which is I want to name it as "number_difference" between 2 tables that required a numeric (in this case as a quantity).
I have 2 tables that totally same, let say, I modify the value from table A so some value in table A different with table B. And I want to join it into 1 table that display rows that some values were modified. I already get the result by this query :
**
select a.T1, a.T2 a.T3 ... from A where not exists (select * from B
where a.T1=b.T1 and a.T2=b.T2 and a.T3=b.T3)
**
This query works well. But, I want to add more field, the difference number between this 2 field (quantity) in 2 different tables. So let say, a.T3 and b.T3 are quantities. And want to display it as "number_difference" next to field (T2) which I display. Sorry I can't post images, they say I need at least 10 reputation to post. Please help me master, how can I make it everytime I use join/inner join it always display soo many rows that I only need the rows which a value from 1 table I have modified.
Thanks in advance.
You can get something like this
Select * From A Where A.id not in( Select Id from B)
or
Select A.* From A left join B on A.id = B.id Where A.id <> B.id
If you are specifically targeting a situation with two identical tables, where one underwent UPDATE operations only (no INSERT), and you want to identify those records which were modified, then:
select a.* from a, b where a.id=b.id and ( a.c1!=b.c1 or a.c2!=b.c2)
Okay, so I've got two tables. One table (table 1) contains a column Books_Owned_ID which stores a series of numbers in the form of 1,3,7. I have another table (table 2) which stores the Book names in one column and the book ID in another column.
What I want to do is create an SQL code which will take the numbers from Books_Owned_IDand display the names of those books in a new column. Like so:
|New Column |
Book 1 Name
Book 2 Name
Book 3 Name
I can't wrap my head around this, it's simple enough but all the threads I look on get really confusing.
Table1 contains the following columns:
|First_Name| Last_Name| Books_Owned_ID |
Table2 contains the following columns:
|Book_Name|Book_ID|
You need to do an inner join. This is a great example/reference for these
SELECT Book_Name FROM Table2
INNER JOIN Table1
ON Table1.Books_Owned_ID = Table2.Book_ID
EDIT SQL Fiddle
I will work on getting the column comma split working. It wont be a lot extra for this.
EDIT 2 See this answer to build a function to split your string. Then you can do this:
SELECT Book_Name FROM Table2
WHERE Book_ID IN(SELECT FN_ListToTable(',',Table1.Books_Owned_ID) FROM Table1 s)
The core of this centers around data normalisation... Each fact is stored only once (and so is "authoritative"). You should also get into the habit of only storing a single fact in any field.
So, imagine the following table layouts...
Books
Id, Name, Description
Users
Id, Username, EmailAddress, PasswordHash, etc....
BooksOwned
UserId, BookId
So if a single user owns multiple books, there will be multiple entries in the BooksOwned table...
UserId, BookID
1, 1
1, 2
1, 3
Indicates that User 1 owns books 1 through 3.
The reason to do it this way is that it makes it much easier to query in future. You also treat BookId as an Integer instead of a string containing a list - so you don't need to worry about string manipulation to do your query.
The following would return the name of all books owned by the user with Id = 1
SELECT Books.Name
FROM BooksOwned
INNER JOIN Books
ON BooksOwned.BookId = Books.Id
WHERE BooksOwned.UserId = 1
You need a function which takes a comma separated list and returns a table. This is slow and fundamentally a bad idea. Really all this does is convert this way of doing it to be like the data model I describe below. (see ProfessionalAmateur's answer for an example of this).
If you are just starting change your data model. Make a linking table. Like this:
Okay, so I've got two tables. One table (table 1) contains a column Books_Owned_ID which stores a series of numbers in the form of 1,3,7. I have another table (table 2) which stores the Book names in one column and the book ID in another column.
What I want to do is create an SQL code which will take the numbers from Books_Owned_IDand display the names of those books in a new column. Like so:
Person Table
|First_Name| Last_Name| Person_ID |
Book Table
|Book_Name|Book_ID|
PersonBook Table
|PersonID|BookID|
This table can have more than one row for each person.
Lets suppose that I have a table A with couple of columns. I work with tables, where there is no index on the entries, since they are 'historical' tables. I use one specific column, though, to sort of identify my things. Lets call this ID.
If you'd make a query like the one below, sometimes you'd get one line back, other cases a few.
SELECT * FROM A WHERE ID = '<something>'
Lets say I have two more tables, B and C. Both have ID columns, like A.
Also, some of the IDs in A, are also in B OR C. IDs existing in B CANNOT exist in C. And ALL IDs in A EXIST in either B OR C.
B and C contain extra information, which I'd like to join to A at the same SELECT.
My problem is, that they would only provide extra information. I do not want extra lines in my output..
To make it more clear: my selection from A returns a hundred lines of output.
When I left/right/inner join B table, I —probably— will have less lines as output. Same thing with joining C.
AND FINALLY, my question is:
Is there a way to join table B only on those IDs, which exist in B and vice versa? (And it I would want it in the same SELECT.... statement.)
If you don't want extra lines in your output, you could do something like this:
select *
from A join
(select B.*
from B
group by B.id
) B
on A.id = B.id;
This would choose arbitrary values from B for each id and join them back to A. Is this what you want?
Well it seems like you should build some left join between A and two "Select MAX"s: one from table B, the other one from table C.
And if you do not want 'duplicate' IDs from table A, a 'group by' on table A should help.