CatID parID catName
1 -1 A
2 1 B
3 2 C
4 3 D
I want to write a query which returns the parent child relationship in string format.
In the above table the catName has parentId -1, which means it has got no parent. B has parentID 1, which means that A is its parent.
So finaly the string is like this
A=>B=>c=>D
This is the way I want to generate a query.
I'll pass CatID, and it will traverse until it gets a -1.
declare #CatID int;
set #CatID = 4;
with C as
(
select parID,
cast(catName as varchar(max)) as catName
from YourTable
where CatID = #CatID
union all
select T.parID,
T.catName + '=>' + C.catName
from YourTable as T
inner join C
on T.CatID = C.parID
)
select catName
from C
where parID = -1
SE-Data
As a partial answer, it sounds like you need a recursive query. Here is a StackOverflow thread with some good information on recursive queries. As to how to use a query to turn it into a single string, I don't know... that part may be more optimized for a programming language.
you need to define function then call it in recursive loop.
You can use MPTT (Modified Preorder Tree Traversal) to store nested tree or hierarchical data.
this article describe how to get hierarchical "breadcrumb" within a single query.
Related
I have a product page on a webpage that shows categories of products. This is done with a listview populated from a database. The issue that I have is that the main supplier has demanded that their products are first in the category list. So what I need to do is run a query that will return the results, display those two categories first and then display the rest alphabetically.
So I've been trying to do this using a UNION ALL query like this:
SELECT cat, cat_id, image FROM prod_categories WHERE cat_id = 19 OR cat_id = 65
UNION ALL
SELECT cat, cat_id, image FROM prod_categories WHERE cat_id <> 19 AND cat_id <> 65
I thought with a union like this it would display the results of the first select query first, but it's not doing that.
I can add an 'order by cat' clause on the end, but obviously that only displays them in the correct order if the two categories I want to display come first alphabetically, which they don't.
If anyone has any ideas how to do this it would be greatly appreciated.
Thanks
How about this:
SELECT cat, cat_id, image FROM prod_categories
order by case when cat_id in (19, 65) then 1 else 2 end, cat_id
Cuts out the need to UNION altogether. Might even produce a more efficient execution plan (possibly...).
(using Transact-SQL for SQL Server - the exact syntax may have to be tinkered for MySql etc)
Try something like this.
SELECT cat, cat_id, image, 1 as [srt]
FROM prod_categories WHERE cat_id = 19 OR cat_id = 65
UNION ALL
SELECT cat, cat_id, image, 2 as [srt]
FROM prod_categories WHERE cat_id <> 19 AND cat_id <> 65
ORDER BY srt ASC, cat_id
Don't hard-code this into your query. What happens when the next supplier wants to come second? Or last? For that matter, you may want to list categories in some sort of "group", anyways.
Instead, you should be using an ordering table (or multiple). Something simple to get you started:
CREATE TABLE Category_Order (categoryId INTEGER -- fk to category.id, unique
priority INTEGER) -- when to display category
Then you want to insert the values for the current "special" categories:
INSERT INTO Category_Order (categoryId, priority) VALUES (19, 2147483647), (65, 0)
You'll also need an entry for rows that are not currently prioritized:
INSERT INTO Category_Order (categoryId, priority)
SELECT catId, -2147483648
FROM prod_categories
WHERE catID NOT IN (19, 65)
Which can then be queried like this:
SELECT cat, cat_id, image
FROM prod_categories
JOIN Category_Order
ON category_id = cat_id
ORDER BY priority DESC, cat
If you write a small maintenance program for this table, you can then push re-ordering duties off onto the correct business department. Reordering of entries can be accomplished by splitting the difference between existing entries, although you'll want a procedure to re-distribute if things get too crowded.
Note that, in the event your db supports a clause like ORDER BY priority NULLS LAST, the entries for non-prioritized categories are unnecessary, and you can simply LEFT JOIN to the ordering table.
How can I put a table name dynamically in a query?
Suppose I have a query as shown below:
Select a.amount
,b.sal
,a.name
,b.address
from alloc a
,part b
where a.id=b.id;
In the above query I want to use a table dynamically (part b if the database is internal, p_part b if the database if external).
I have a function that returns which database it is. Suppose the function is getdatabase();
select decode(getdatabase(),'internal','part b','external','p_part b')
from dual;
How can I use this function in my main query to insert the table name dynamically into the query?
I don't want to implement this using the primitive way of by appending strings to make a final query and then open cursor with that string.
I don't want to implement this with primitive way of by appending
strings to make a final query and then open cursor with that string .
That's really the only way you can do it. It's not possible to use a variable or function call for the table name when using a regular PL/SQL SQL block, you have to use dynamic SQL.
Refer to Oracle documentation for more details:
http://docs.oracle.com/cd/B10500_01/appdev.920/a96590/adg09dyn.htm
Here's an example from the doc:
EXECUTE IMMEDIATE 'SELECT d.id, e.name
FROM dept_new d, TABLE(d.emps) e -- not allowed in static SQL
-- in PL/SQL
WHERE e.id = 1'
INTO deptid, ename;
You can do this without dynamic SQL, assuming both tables (part and p_part) are available at compile time:
select a.amount
,b.sal
,a.name
,b.address
from alloc a
,part b
where a.id=b.id
and (select getdatabase() from dual) = 'internal'
UNION ALL
select a.amount
,b.sal
,a.name
,b.address
from alloc a
,p_part b
where a.id=b.id
and (select getdatabase() from dual) = 'external'
;
I've put the function call in a subquery so that it is run only once per call (i.e. twice, in this instance).
I have a stored procedure which uses the IN clause. In my ASP.NET application, I have a multiline textbox that supplies values to the stored procedure. I want to be able to order by the values as they were entered in the textbox. I found out how to do this easily in mySQL (using FIELD function), but not a SQL Server equivalent.
So my query looks like:
Select * from myTable where item in #item
So I would be passing in values from my application like '113113','112112','114114' (in an arbitrary order). I want to order the results by that list.
Would a CASE statement be feasible? I wouldn't know how many items are coming in the textbox data.
How are you parameterising the IN clause?
As you are on SQL Server 2008 I would pass in a Table Valued Parameter with two columns item and sort_order and join on that instead. Then you can just add an ORDER BY sort_order onto the end.
From KM's comment above...
I know you didn't state it is comma seperated, but if it was a CSV or even if you have it space seperated you could do the following.
DECLARE #SomeTest varchar(100) --used to hold your values
SET #SomeTest = (SELECT '68,72,103') --just some test data
SELECT
LoginID --change to your column names
FROM
Login --change to your source table name
INNER JOIN
( SELECT
*
FROM fn_IntegerInList(#SomeTest)
) n
ON
n.InListID = Login.LoginID
ORDER BY
n.SortOrder
And then create fn_IntegerInList():
CREATE FUNCTION [dbo].[fn_IntegerInList] (#InListString ntext)
RETURNS #tblINList TABLE (InListID int, SortOrder int)
AS
BEGIN
declare #length int
declare #startpos int
declare #ctr int
declare #val nvarchar(50)
declare #subs nvarchar(50)
declare #sort int
set #sort=1
set #startpos = 1
set #ctr = 1
select #length = datalength(#InListString)
while (#ctr <= #length)
begin
select #val = substring(#InListString,#ctr,1)
if #val = N','
begin
select #subs = substring(#InListString,#startpos,#ctr-#startpos)
insert into #tblINList values (#subs, #sort)
set #startpos = #ctr+1
end
if #ctr = #length
begin
select #subs = substring(#InListString,#startpos,#ctr-#startpos)
insert into #tblINList values (#subs, #sort)
end
set #ctr = #ctr +1
set #sort = #sort + 1
end
RETURN
END
This way your function creates a table that holds a sort order namely, SortOrder and the ID or number you are passing in. You can of course modify this so that you are looking for space rather then , values. Otherwise Martin has the right idea in his answer. Please note in my example I am using one of my tables, so you will need to change the name Login to whatever you are dealing with.
the same way you concatenate ('113113','112112','114114') to pass to the sql sentence in the where clausule you can concatenate
order by
case item
when '113113' then 1
when '112112' then 2
when '114114' then 3
end
to pass to your order by clausule
The query is this one:
SELECT FriendID FROM Relationships WHERE UserID = 1
INTERSECT
(SELECT FriendID FROM Relationships WHERE UserID = 2
UNION SELECT UserID FROM Relationships WHERE FriendID = 2)
(for the curious readers, please note that the friend relationship is not necessarily symmetrical in this scenario)
I've tried all the possible combination of parentheses with no luck.
If I omit the parentheses, there's no operator precedence in the sense that it reads it like 5+6*3 = 33, so if I put the union before the intersection, the query works fine. But what will I do when I will have to intersect two unions?
You can use temporary tables in such case.
Thanks to Larry Lustig (which pointed me this), I rewrote my query as follows
SELECT FriendID FROM Relationships WHERE UserID = 1
INTERSECT SELECT ID FROM
(SELECT FriendID AS ID FROM Relationships WHERE UserID = 2
UNION SELECT UserID AS ID FROM Relationships WHERE FriendID = 2)
And it works.
Sorry for this simple question .
I have a Stored Procedure that return an int value , I'm trying to call this sp from my asp.net linq to sql project .
int currentRating = db.sproc_GetAverageByPageId(pageId);
But i get this error :
Cannot implicitly convert type `'System.Data.Linq.ISingleResult<PsychoDataLayer.sproc_GetAverageByPageId> to 'int' .`
Edit 1
The solution that friends implied didn't work . All the time it return 0
For more information i put my stored procedure here :
ALTER procedure [dbo].[sproc_GetAverageByPageId](
#PageId int )
as
select (select sum(score) from votes where pageId = #PageId)/(select count(*) from votes where pageId=#PageId)
You should inspect the ReturnValue property.
Perhaps the following works better?
int currentRating = (int)db.sproc_GetAverageByPageId(pageId).ReturnValue;
Update: since your stored proc returns a resultset instead of using a return statement the actual data will be available as an element in the enumerable returned by db.sproc_GetAverageByPageId(pageId). If you inspect the ISingleResult<T> type, you'll see that it inherits IEnumerable<T> which indicates that you can enumerate the object to get to the data, each element being of type T.
Since the sproc does a SELECT SUM(*) ... we can count on the resultset to always contain one row. Thus, the following code will give you the first (and only) element in the collection:
var sumRow = db.sproc_GetAverageByPageId(pageId).Single();
Now, the type of sumRow will be T from the interface definition, which in your case is PsychoDataLayer.sproc_GetAverageByPageId. This type hopefully contains a property that contains the actual value you are after.
Perhaps you can share with us the layout of the PsychoDataLayer.sproc_GetAverageByPageId type?
Looks like you're actually after the ReturnValue. You may need to cast it to System.Data.Linq.ISingleResult if it isn't already, then cast ReturnValueto int.
This is actually returning an ISingleResult
int currentRating = (int) db.sproc_GetAverageByPageId(pageId).ReturnValue;
Change your sp to :
ALTER procedure [dbo].[sproc_GetAverageByPageId](
#PageId int )
as
return (select sum(score) from votes where pageId = #PageId)/(select count(*) from votes where pageId=#PageId)
one more thing you can do:
ALTER procedure [dbo].[sproc_GetAverageByPageId](#PageId int ) as
select (select sum(score) from votes where pageId = #PageId)/(SELECT * FROM votes where pageId=#PageId)
WRITE >>
"select * From"<< instead of "select Count(*)"
select (select sum(score) from votes where pageId = #PageId)/(SELECT * FROM votes where pageId=#PageId)
and after that:
int currentRating = (int)db.sproc_GetAverageByPageId(pageId).count();