So I need an SQL function that will concatenate a bunch of row values into one varchar.
I have the functions written but right now I'm focused on what is the better choice for performance.
The Scalar Function is
CREATE FUNCTION fn_GetPatients_ByRecipient (#recipient int)
RETURNS varchar(max)
AS
BEGIN
DECLARE #patients varchar(max)
SET #patients = ''
SELECT #patients = #patients + convert(varchar, Patient) + ';' FROM RecipientsPatients WHERE Recipient = #recipient
RETURN #patients
END
The Inline Function just returns a table of all the values instead of concatenating them.
CREATE FUNCTION fn_GetPatients_ByRecipient (#recipient int)
RETURNS TABLE
AS
RETURN
(
SELECT Patient FROM RecipientsPatients WHERE Recipient = #recipient
)
I would then take this table in a separate function and concatenate them together. I was thinking the second choice is best since I will be going row by row through a smaller data set. Any opinions on what I'm doing right/wrong would be appreciated.
Thanks
This problem of string concatenation in SQL Server has several solutions, and the pros and cons are discussed in Concatenating Row Values in Transact-SQL and other similar articles on the web.
My favourite solution is using the FOR XML PATH(' ') trick. The chain assignment method you use works fine, although is not officialy supported and hence may break in future. Your method should be among the fastest possible, if not the fastes, as long as the table valued function does not perform a full scan, ie. you have an index on Recipient that covers Patient (use include).
The only thing I would add is to declare both functions WITH SCHEMABINDING, this has side effects that improve performance.
See here for an example of using the FOR XML PATH trick
set nocount on;
declare #t table (id int, name varchar(20), x char(1))
insert into #t (id, name, x)
select 1,'test1', 'a' union
select 1,'test1', 'b' union
select 1,'test1', 'c' union
select 2,'test2', 'a' union
select 2,'test2', 'c' union
select 3,'test3', 'b' union
select 3,'test3', 'c'
SELECT p1.id, p1.name,
stuff((SELECT ', ' + x
FROM #t p2
WHERE p2.id = p1.id
ORDER BY name, x
FOR XML PATH('') ), 1,2, '') AS p3
FROM #t p1
GROUP BY
id, name
it returns
1 test1 a, b, c
2 test2 a, c
3 test3 b, c
Have a look at Adam Machanic's results from his Grouped String Concatenation Contest:
http://web.archive.org/web/20150328021904/http://sqlblog.com/blogs/adam_machanic/archive/2009/05/31/grouped-string-concatenation-the-winner-is.aspx
It has the code to show you the most efficient way to do this. Peter Larsson, who won the contest, used a combination of tricks including XML PATH to accomplish the task. There was some debate later about whether it was the most efficient solution based on subsequent tests of other submissions. Make sure you check the comments to know what scripts to look at in the zip file you can download there. Generally FOR XML PATH('') is the fastest though.
Related
I am working on a sql database which will provide with data some grid. The grid will enable filtering, sorting and paging but also there is a strict requirement that users can enter free text to a text input above the grid for example
'Engine 1001 Requi' and that the result will contain only rows which in some columns contain all the pieces of the text. So one column may contain Engine, other column may contain 1001 and some other will contain Requi.
I created a technical column (let's call it myTechnicalColumn) in the table (let's call it myTable) which will be updated each time someone inserts or updates a row and it will contain all the values of all the columns combined and separated with space.
Now to use it with entity framework I decided to use a table valued function which accepts one parameter #searchQuery and it will handle it like this:
CREATE FUNCTION myFunctionName(#searchText NVARCHAR(MAX))
RETURNS #Result TABLE
( ... here come columns )
AS
BEGIN
DECLARE #searchToken TokenType
INSERT INTO #searchToken(token) SELECT value FROM STRING_SPLIT(#searchText,' ')
DECLARE #searchTextLength INT
SET #searchTextLength = (SELECT COUNT(*) FROM #searchToken)
INSERT INTO #Result
SELECT
... here come columns
FROM myTable
WHERE (SELECT COUNT(*) FROM #searchToken WHERE CHARINDEX(token, myTechnicalColumn) > 0) = #searchTextLength
RETURN;
END
Of course the solution works fine but it's kinda slow. Any hints how to improve its efficiency?
You can use an inline Table Valued Function, which should be quite a lot faster.
This would be a direct translation of your current code
CREATE FUNCTION myFunctionName(#searchText NVARCHAR(MAX))
RETURNS TABLE
AS RETURN
(
WITH searchText AS (
SELECT value token
FROM STRING_SPLIT(#searchText,' ') s(token)
)
SELECT
... here come columns
FROM myTable t
WHERE (
SELECT COUNT(*)
FROM searchText
WHERE CHARINDEX(s.token, t.myTechnicalColumn) > 0
) = (SELECT COUNT(*) FROM searchText)
);
GO
You are using a form of query called Relational Division Without Remainder and there are other ways to cut this cake:
CREATE FUNCTION myFunctionName(#searchText NVARCHAR(MAX))
RETURNS TABLE
AS RETURN
(
WITH searchText AS (
SELECT value token
FROM STRING_SPLIT(#searchText,' ') s(token)
)
SELECT
... here come columns
FROM myTable t
WHERE NOT EXISTS (
SELECT 1
FROM searchText
WHERE CHARINDEX(s.token, t.myTechnicalColumn) = 0
)
);
GO
This may be faster or slower depending on a number of factors, you need to test.
Since there is no data to test, i am not sure if the following will solve your issue:
-- Replace the last INSERT portion
INSERT INTO #Result
SELECT
... here come columns
FROM myTable T
JOIN #searchToken S ON CHARINDEX(S.token, T.myTechnicalColumn) > 0
For the last few days, I've been reading an ebook on data structures and well, frankly speaking, many things are already gone from my head. Just reviewing them and trying to make clear again. I was going through hash tables and get to familiar with it again. So I know and heard, SQL Server uses hash tables internally and many of the threads of stackoverflow.com and forums.asp.net asked about creating hash tables in SQL Server as it stores temporary data. So let me give an example that I've used in a stored procedure using temp table: (Avoid it and it's too long. Just for an example)
1st:
CREATE PROCEDURE [dbo].[Orders]
#OrderLine int
AS
BEGIN
DECLARE #t1 TABLE(Date1 date,
OrderID VARCHAR(MAX),
EmployeeName VARCHAR(MAX),
DeliveryDate date,
StoreName VARCHAR(MAX),
DeliveryAddress VARCHAR(MAX),
ItemName VARCHAR(MAX),
Quantity FLOAT)
INSERT INTO #t1(Date1, OrderID, EmployeeName, DeliveryDate, StoreName, DeliveryAddress, ItemName, Quantity)
(SELECT DISTINCT
CONVERT(VARCHAR(11), DemandOrder.POCreationDate, 6) AS DemandOrderDate,
DemandOrder.OrderID, EmployeeDetails.EmployeeName,
CONVERT(DATE, DemandOrder.DeliveryDate) AS ExpectedDeliveryDate,
StoreDetails.StoreName,
DemandOrder.DeliveryAddress, Item.ItemName,
DemandOrderLine.Quantity
FROM
DemandOrder
INNER JOIN
DemandOrderLine ON DemandOrder.OrderID = DemandOrderLine.OrderID
INNER JOIN
Item on DemandOrderLine.ItemID=Item.ItemID
INNER JOIN
EmployeeDetails ON EmployeeDetails.EmployeeID = DemandOrder.EmployeeID
INNER JOIN
StoreDetails ON DemandOrderLine.StoreID = StoreDetails.StoreID
WHERE
DemandOrderLine.OrderLine = #OrderLine)
DECLARE #t2 TABLE(Approvedby VARCHAR(MAX))
INSERT INTO #t2(Approvedby)
(SELECT EmployeeDetails.EmployeeName
FROM EmployeeDetails
INNER JOIN DemandOrderLine ON DemandOrderLine.ApprovedBy = EmployeeDetails.EmployeeID)
SELECT DISTINCT
CONVERT(VARCHAR(11), Date1, 6) AS Date,
OrderID, EmployeeName,
CONVERT(VARCHAR(11), DeliveryDate, 6) AS ExpectedDeliveryDate,
StoreName, Approvedby, DeliveryAddress,
ItemName, Quantity
FROM
#t1
CROSS JOIN
#t2
END
Another one, from an example, that says in stored procedure, hash tables can't be used. So here it's:
2nd:
CREATE PROCEDURE TempTable AS ---- It's actually not possible in SP
CREATE table #Color
(
Color varchar(10) PRIMARY key
)
INSERT INTO #color
SELECT 'Red'
UNION
SELECT 'White'
UNION
SELECT 'green'
UNION
SELECT 'Yellow'
UNION
SELECT 'blue'
DROP TABLE #color
CREATE table #Color
(
Color varchar(10) PRIMARY key
)
INSERT INTO #color
SELECT 'Red'
UNION
SELECT 'White'
UNION
SELECT 'green'
UNION
SELECT 'Yellow'
UNION
SELECT 'blue'
DROP TABLE #color
GO
So my question is can I say the 1st one is an example of hash table as it uses temp tables and if not, why can't we use it in the stored procedure? Again, if it's created internally, why do we need to create a hash table again for working purposes (Though it has performance issues, just wondering to know if the above examples serve for the purpose). Thanks.
Note: I faced an interview last month and was discussing about it. That's why making sure if I was correct in my views.
Hash-based algorithms are important for any powerful database. These are used for aggregation and join operations. Hash-based joins have been there since version 7.0 -- which is really old (thanks to Martin Smith). You can read more about them in the documentation.
SQL Server 2014 introduced hash-based indexes for memory optimized tables (see here). These are an explicit use of hash tables. In general, though, the tree-based indexes are more powerful because they can be used in more situations:
For range lookups (including like).
For partial key matches.
For order by.
A hash index can only be used for an exact equality match (and group by).
I know im a little late to the party, but I dont think anyone has directly answered your original question.
The first is an example of a table variable and the second is an example of a local table, both are created in the tempdb
The difference between them is that a table variable is not created in memory and cant have a clustered index.
Also a local (hash) table will stick around until that single connection ends, while a table variable is only available for the batch its declared in.
A global table (using a double hash before it) will be available to all connections and persist until all connections using it are closed.
One final thing, the only reason you cant use that local table in a stored procedure is because it uses the same name twice, even though you've used drop table it evaluates it based on the creates in the batch first. So it wont execute anything and moan it already exists.
DECLARE #SEPERATOR as VARCHAR(1)
DECLARE #SP INT
DECLARE #VALUE VARCHAR(MAX)
SET #SEPERATOR = ','
CREATE TABLE #TempCode (id int NOT NULL)
/**this Region For Storing SiteCode**/
WHILE PATINDEX('%' + #SEPERATOR + '%', #Code ) <> 0
BEGIN
SELECT #SP = PATINDEX('%' + #SEPERATOR + '%' ,#Code)
SELECT #VALUE = LEFT(#Code , #SP - 1)
SELECT #Code = STUFF(Code, 1, #SP, '')
INSERT INTO #TempCode (id) VALUES (#VALUE)
END
I'm using Firebird 2.1.
There is a table: IDs, Labels
There can be multiple labels for the same ID:
10 Peach
10 Pear
10 Apple
11 Apple
12 Pear
13 Peach
13 Apple
Let's say I have a set of labels, ie.: (Apple, Pear, Peach).
How can I write a single select to return all IDs that have all labels associated in a given set? Preferably I'd like to specify the set in a string separated with commas, like: ('Apple', 'Pear', 'Peach') -› this should return ID = 10.
Thanks!
As asked, I'm posting my simpler version of piclrow's answer. I have tested this on my Firebird, which is version 2.5, but the OP (Steve) has tested it on 2.1 and it works as well.
SELECT id
FROM table
WHERE label IN ('Apple', 'Pear', 'Peach')
GROUP BY id
HAVING COUNT(DISTINCT label)=3
This solution has the same disadvantage as pilcrow's... you need to know how many values you are looking for, as the HAVING = condition must match the WHERE IN condition. In this respect, Ed's answer is more flexible, as it splits the concatenated value string parameter and counts the values. So you just have to change the one parameter, instead of the 2 conditions I and pilcrow use.
OTOH, if efficency is of concern, I would rather think (but I am absolutely not sure) that Ed's CTE approach might be less optimizable by the Firebird engine than the one I suggest. Firebird is very good at optimizing queries, but I don't really now if it is able to do so when you use CTE this way. But the WHERE + GROUP BY + HAVING should be optimizable by simply having an index on (id,label).
In conclusion, if execution times are of concern in your case, then you probably need some explain plans to see what is happening, whichever solution you choose ;)
It's easiest to split the string in code and then query
SQL> select ID
CON> from (select ID, count(DISTINCT LABEL) as N_LABELS
CON> from T
CON> where LABEL in ('Apple', 'Pear', 'Peach')
CON> group by 1) D
CON> where D.N_LABELS >= 3; -- We know a priori we have 3 LABELs
ID
============
10
If it is acceptable to create a helper stored procedure that will be called from the primary select then consider the following.
The Helper stored procedure takes in a delimited string along with the delimiter and returns a row for each delimited string
CREATE OR ALTER PROCEDURE SPLIT_BY_DELIMTER (
WHOLESTRING VARCHAR(10000),
SEPARATOR VARCHAR(10))
RETURNS (
ROWID INTEGER,
DATA VARCHAR(10000))
AS
DECLARE VARIABLE I INTEGER;
BEGIN
I = 1;
WHILE (POSITION(:SEPARATOR IN WHOLESTRING) > 0) DO
BEGIN
ROWID = I;
DATA = TRIM(SUBSTRING(WHOLESTRING FROM 1 FOR POSITION(TRIM(SEPARATOR) IN WHOLESTRING) - 1));
SUSPEND;
I = I + 1;
WHOLESTRING = TRIM(SUBSTRING(WHOLESTRING FROM POSITION(TRIM(SEPARATOR) IN WHOLESTRING) + 1));
END
IF (CHAR_LENGTH(WHOLESTRING) > 0) THEN
BEGIN
ROWID = I;
DATA = WHOLESTRING;
SUSPEND;
END
END
Below is the code to call, I am using Execute block to demonstrate passing in the delimited string
EXECUTE BLOCK
RETURNS (
LABEL_ID INTEGER)
AS
DECLARE VARIABLE PARAMETERS VARCHAR(50);
BEGIN
PARAMETERS = 'Apple,Peach,Pear';
FOR WITH CTE
AS (SELECT ROWID,
DATA
FROM SPLIT_BY_DELIMITER(:PARAMETERS, ','))
SELECT ID
FROM TABLE1
WHERE LABELS IN (SELECT DATA
FROM CTE)
GROUP BY ID
HAVING COUNT(*) = (SELECT COUNT(*)
FROM CTE)
INTO :LABEL_ID
DO
SUSPEND;
END
I have a product table with a tag column, each product has multiple tags stored in this format: "|technology|mobile|acer|laptop|" ...second product's tags could look like this "|computer|laptop|toshiba|"
I am using MS SQL Server 2008 and stored procedure, I would like to know how I could pass a string like "|computer|laptop|" and get both records returned as they both have the tag laptop in them and if I passed "|computer|" only the second record would return as it is the only one comtainning that tag.
What is the best way of doing this without performance penalties using stored procedure?
I have so far had no luck with different codes i have found on the internet, I really hope you guys can maybe help me with this, thank you.
I agree with the other posters that storing data in a column like that is going to cause headaches. You really want to store those tags in a child table so you can easily and efficiently join them. If it's an inherited system or something you can't refactor right away you can write a split function.
The typical sql split implementation uses a while loop and a table variable in a multi-statement TVF. Every iteration incurs more I/O and CPU overhead. Performance testing on SQL 2005 SP1 showed that this overhead is hidden from the I/O Stats and query plan. Profiling the code will reveal the true cost.
Rewriting that function into a inline TVF is much more efficient. The primary difference between an inline and multi-statement TVF is the Query Optimizer will merge the inline function into the query before processing; this eliminates the overhead from the function call. Also, since there is no table variable required, the additional I/O cost is eliminated. Finally, you avoid the costly iterative processing.
Here is the fastest, most scalable split function I could come up with including unit tests and summary.
This function requires a numbers table:
CREATE TABLE dbo.Numbers
(
NUM INT PRIMARY KEY CLUSTERED
)
;WITH Nbrs ( n ) AS
(
SELECT 1 UNION ALL
SELECT 1 + n FROM Nbrs WHERE n < 10000
)
INSERT INTO dbo.Numbers
SELECT n FROM Nbrs
OPTION ( MAXRECURSION 10000 )
The source of the function is here:
IF EXISTS (
SELECT 1
FROM dbo.sysobjects
WHERE id = object_id(N'[dbo].[ParseString]')
AND xtype in (N'FN', N'IF', N'TF'))
BEGIN
DROP FUNCTION [dbo].[ParseString]
END
GO
CREATE FUNCTION dbo.ParseString (#String VARCHAR(8000), #Delimiter VARCHAR(10))
RETURNS TABLE
AS
/*******************************************************************************************************
* dbo.ParseString
*
* Creator: MagicMike
* Date: 9/12/2006
*
*
* Outline: A set-based string tokenizer
* Takes a string that is delimited by another string (of one or more characters),
* parses it out into tokens and returns the tokens in table format. Leading
* and trailing spaces in each token are removed, and empty tokens are thrown
* away.
*
*
* Usage examples/test cases:
Single-byte delimiter:
select * from dbo.ParseString2('|HDI|TR|YUM|||', '|')
select * from dbo.ParseString('HDI| || TR |YUM', '|')
select * from dbo.ParseString(' HDI| || S P A C E S |YUM | ', '|')
select * from dbo.ParseString2('HDI|||TR|YUM', '|')
select * from dbo.ParseString('', '|')
select * from dbo.ParseString('YUM', '|')
select * from dbo.ParseString('||||', '|')
select * from dbo.ParseString('HDI TR YUM', ' ')
select * from dbo.ParseString(' HDI| || S P A C E S |YUM | ', ' ') order by Ident
select * from dbo.ParseString(' HDI| || S P A C E S |YUM | ', ' ') order by StringValue
Multi-byte delimiter:
select * from dbo.ParseString('HDI and TR', 'and')
select * from dbo.ParseString('Pebbles and Bamm Bamm', 'and')
select * from dbo.ParseString('Pebbles and sandbars', 'and')
select * from dbo.ParseString('Pebbles and sandbars', ' and ')
select * from dbo.ParseString('Pebbles and sand', 'and')
select * from dbo.ParseString('Pebbles and sand', ' and ')
*
*
* Notes:
1. A delimiter is optional. If a blank delimiter is given, each byte is returned in it's own row (including spaces).
select * from dbo.ParseString3('|HDI|TR|YUM|||', '')
2. In order to maintain compatibility with SQL 2000, ident is not sequential but can still be used in an order clause
If you are running on SQL2005 or later
SELECT Ident, StringValue FROM
with
SELECT Ident = ROW_NUMBER() OVER (ORDER BY ident), StringValue FROM
*
*
* Modifications
*
*
********************************************************************************************************/
RETURN (
SELECT Ident, StringValue FROM
(
SELECT Num as Ident,
CASE
WHEN DATALENGTH(#delimiter) = 0 or #delimiter IS NULL
THEN LTRIM(SUBSTRING(#string, num, 1)) --replace this line with '' if you prefer it to return nothing when no delimiter is supplied. Remove LTRIM if you want to return spaces when no delimiter is supplied
ELSE
LTRIM(RTRIM(SUBSTRING(#String,
CASE
WHEN (Num = 1 AND SUBSTRING(#String,num ,DATALENGTH(#delimiter)) <> #delimiter) THEN 1
ELSE Num + DATALENGTH(#delimiter)
END,
CASE CHARINDEX(#Delimiter, #String, Num + DATALENGTH(#delimiter))
WHEN 0 THEN LEN(#String) - Num + DATALENGTH(#delimiter)
ELSE CHARINDEX(#Delimiter, #String, Num + DATALENGTH(#delimiter)) - Num -
CASE
WHEN Num > 1 OR (Num = 1 AND SUBSTRING(#String,num ,DATALENGTH(#delimiter)) = #delimiter)
THEN DATALENGTH(#delimiter)
ELSE 0
END
END
)))
End AS StringValue
FROM dbo.Numbers
WHERE Num <= LEN(#String)
AND (
SUBSTRING(#String, Num, DATALENGTH(ISNULL(#delimiter,''))) = #Delimiter
OR Num = 1
OR DATALENGTH(ISNULL(#delimiter,'')) = 0
)
) R WHERE StringValue <> ''
)
For your case, you could use it like this:
--SAMPLE DATA
CREATE TABLE #products
(
productid INT IDENTITY PRIMARY KEY CLUSTERED ,
prodname VARCHAR(200),
tags VARCHAR(200)
)
INSERT INTO #products (prodname, tags)
SELECT 'toshiba laptop', '|laptop|toshiba|notebook|'
UNION ALL
SELECT 'toshiba netbook', '|netbook|toshiba|'
UNION ALL
SELECT 'Apple macbook', '|laptop|apple|notebook|'
UNION ALL
SELECT 'Apple mouse', '|apple|mouse'
--Actual solution
DECLARE #searchTags VARCHAR(200)
SET #searchTags = '|apple|laptop|' --This would the string that would get passed in if it were a stored procedure
--First we convert the supplied tags into a table for use later
--My (2005) dev box raised a severe error attempting to do the search in 1 step
--hence the temp table
CREATE TABLE #tags
(
tag VARCHAR(200) PRIMARY KEY CLUSTERED
)
INSERT INTO #tags --The function splits the string up into one record for each value
SELECT stringValue
FROM dbo.parsestring(#searchTags,'|') --SQL 2005 has a real problem joining to a TVF twice, apparently
SELECT DISTINCT p.*
FROM #products P --we join the products table with the function to get a row for each tag so we can compare with the temp table
CROSS APPLY (SELECT stringValue FROM dbo.parsestring(P.tags,'|')) T
WHERE EXISTS(SELECT * FROM #tags WHERE tag = T.stringValue) --we compare the rows with our temp table and if we get matches, the products are returned
/*This will return the Apple Macbook and the Toshiba Laptop because they both contain
the 'laptop' tag and the Apple mouse because it contains the 'apple' tag. The
toshiba netbook contains neither tag so it won't be returned.*/
But, with your tags in a separate table as suggested (1-many for a simplified example) It would look like this:
SELECT * FROM Products P
WHERE EXISTS (SELECT *
FROM tags T
INNER JOIN dbo.parsestring(#tags,'|') Q
ON T.tag = Q.StringValue
WHERE T.productid = P.productiId )
You have a many-to-many relationship between products and tags. The best way of doing this is to redesign your database. Create a table of tags and a junction table that links products with tags.
That's not a very good design. Combining like terms into one field and separating them with a delimiter such as a vertical bar does not scale well and it is very limiting.
I recommend you read up on how to design databases. The best book I ever bought regarding database design was Database Design for Mere Mortals by Michael Hernandez ISBN: 0-201-69471-9. Amazon Listing I noticed he has a second edition.
He walks you through the entire process of (from start to finish) of designing a database. I recommend you start with this book.
You have to learn to look at things in groups or chunks. Database design has simple building blocks just like programming does. If you gain a thorough understanding of these simple building blocks you can tackle any database design.
In programming you have:
If Constructs
If Else Constructs
Do While Loops
Do Until Loops
Case Constructs
With databases you have:
Data Tables
Lookup Tables
One to One relationships
One to Many Relationships
Many to Many relationships
Primary keys
Foreign keys
The simpler you make things the better. A database is nothing more than a place where you put data into cubbie holes. Start by identifying what these cubbie holes are and what kind of stuff you want in them.
You are never going to create the perfect database design the first time you try. This is a fact. Your design will go through several refinements during the process. Sometimes things won't seem apparent until you start entering data, and then you have an ahh ha moment.
The web brings it's own sets of challenges. Bandwith issues. Statelessness. Erroneous data from processes that start but never get finished.
make a split with CLR function return a table with the value or pass as xml and load it into a table varible an make a join
create procedure search
(
#data xml
)
AS
BEGIN
--declare #data xml
declare #LoadData table
(
dataToFind varchar(max)
)
--set #data= cast(
--'<data>
-- <item>computer</item>
-- <item>television</item>
--</data>' as xml)
insert into #LoadData
SELECT T2.Loc.value('.','varchar(max)')
FROM (select #data as data )T
CROSS APPLY data.nodes('/data/item') as T2(Loc)
select * from #LoadData--use for join
END
I would suggest you write an extra couplle of tables that with "proper design,
Populate those tables from the existing not well designed bit - this way y our search will work properly buy others using the old | pipe approach won't notice till you have time to refactor
Lets say we have a following table with two columns and following rows of data in SQLServer-2005:
Tiger 50
Wolf 4
Tiger 53
Lion 55
Elephant 54
Rhino 52
Lion 5
Can we have a sql query that result as following: Tiger,Wolf,Lion,Elephant,Rhino as a single string varchar output?Is it possible ?
using T-SQL not possible singe I am using the result in c# as a result of executescalar
Thank you in advance.
You can use for xml path to concatenate the values:
select distinct name + ', ' as [text()]
from #t
for xml path('')
-->
Elephant, Lion, Rhino, Tiger, Wolf,
Chop of the last 2 bytes if you don't like trailing ,'s.
Not sure why you can't use T-SQL, you can use this in combination with ExecuteScalar() just fine.
Sample data:
declare #t table (name varchar(max), id int)
insert into #t
select 'Tiger', 50
union all select 'Wolf', 4
union all select 'Tiger', 53
union all select 'Lion', 55
union all select 'Elephant', 54
union all select 'Rhino', 52
union all select 'Lion', 5
See How to return multiple values in one column (T-SQL)?
Use GROUP_CONCAT() with DISTINCT:
SELECT GROUP_CONCAT(DISTINCT colName) FROM tblName;
Assuming you are getting this from ExecuteScalar and using the resulting composite string in C#, then you are going to end up writing a sproc, or just having your code work with the datatable.
Can you provide more detail on why you can't use a sproc? A few good examples have been provided that would do fine with that, and you can still get your scalar result
The most efficient way is probably to use a User-Defined Aggregate, but you can also abuse the UPDATE statement:
DECLARE #Result varchar(500)
SET #Result = ''
UPDATE Animals
SET #Result = #Result + Name + ','
SELECT #Result
This is how Andomar's Answer was implemented.Thanks to Andomar's answer got to learn some thing new with this .
select distinct summaryColumn + ', '
as [text()] from tablename for
xml path('')