I am using FOR XML PATH in my stored procedure to concatenate rows.But it gives me performance issue.can any one please tell me a function that i can use instead of for xml path.
You can create a CLR Aggregate function to do concatenation.
Example here: http://www.mssqltips.com/sqlservertip/2022/concat-aggregates-sql-server-clr-function/
You can concatenate storing the string in a variable, just with a simple select.
Example concatenating with a comma:
DECLARE #MyConcatenateData VARCHAR(1000)
SELECT #MyConcatenateData = COALESCE(#MyConcatenateData + ',', '') + MyTextColumn
FROM MyTable
Related
In Sql Server you can run the following query to combine values from multiple rows into a single string variable.
DECLARE #x NVARCHAR(MAX) = N'';
SELECT TOP 5 #x = #x + name + ', '
FROM sys.objects
SELECT #x
Which results in
"sysrscols, sysrowsets, sysclones, sysallocunits, sysfiles1,"
Is there a way to do something similar in PostgreSql? I've tried creating a PostgreSql function that does a SELECT INTO stringVariable but that is only resulting in a single row's worth of values.
Not exactly. The code you have in SQL Server is not actually guaranteed to work. In Postgres, you would use:
select string_agg(name, ', ')
from sys.objects;
If you have a sys.objects table.
Note that in SQL Server, you should do the same thing:
select string_agg(name, ', ')
from sys.objects;
as demonstrated in this SQL Fiddle.
As a note: Your use of the variable is directly contradicted by the documentation:
If a SELECT statement returns more than one row and the variable references a non-scalar expression, the variable is set to the value returned for the expression in the last row of the result set.
That said, I know what you are doing actually works in practice. But I would recommend using string_agg() or in earlier versions using XML for string concatenation.
I have created a user defined table type with a single varchar(max) column with the hopes that I could call my function by passing in an actual query. Of course it didn't work.
My function looks like this:
create function tfnTableToString(#strings TVP_Strings READONLY)
returns varchar(max)
as
begin
return SUBSTRING((SELECT ',' + string FROM #strings FOR XML PATH('')), 2 , 9999)
end
go
As you can see, I'm am just trying to make the code a little simpler by refactoring the process of converting query results into a comma delimited string. Is there a way to do this or am I just stuck having to write the ugly SUBSTRING(... FOR XML PATH...) wherever I need it?
I am trying to remove double quotes " from a column in my SQL export and I get an error, after researching the proper way... this is one of the ways I have tried....
SELECT
'293453' as custnum,
REPLACE(Orders.Order_Comments, '"', '') as FULFILL1,
OrderDetails.OrderID as OrderID2, etc.
The resulting error is:
Your SQL is invalid: Argument data type text is invalid for argument 1 of replace function.
Your Orders.Order_Comments columns is of type text. You can't use the REPLACE() function with that data type. It only works with char/varchar/nchar/nvarchar.
To fix this, the best thing to do is ALTER the table to use a varchar(max) column. The text type is depcrecated, anyway. But, if that's not an option, you'll have to cast it in the query:
REPLACE(CAST(Orders.Order_Comments as varchar(max)), '"', '')
Note that this is potentially very slow.
Take a look at this answer: SQL Server find and replace in TEXT field
The text data type is not valid for use with replace, so you need to cast it as VARCHAR(MAX)
REPLACE(CAST(Orders.Order_Comments AS VARCHAR(MAX)), '"', '')
Try this:
select REPLACE(isnull(Orders.Order_Comments,''), '"', '') as order_comments
from orders
I'm trying to query a table with a column which is xml data with the query and value functions. When using regular string literals it's all okay, but if I put that in a stored procedure and try to use variables it doesn't work.
I suppose I'm not using the correct datatype, but after some searching I can't figure out what datatype the query function wants.
Example:
table contains
| Id | xmldata |
| 1 | <data><node>value</node></data> |
now, using the select query
select id
from table
where xmldata.query('/data/node').value('.', 'VARCHAR(50)') = 'value'
gets me the data I want. But, if I use this in a stored procedure and use a parameter #xpath varchar(100) and pass that to the query method as xmldata.query(#xpath)
i get the error
The argument 1 of the xml data type method "query" must be a string literal.
I guess varchar(100) is not correct, but what datatype can I use that would make MSSQL happy?
Update:
Okay, so. Apparently you can't pass a parameter to the query method "just like that", but one can use the sql:variable in conjunction with local-name to work a part of it out. So, for instance, this will work
declare #xpath VarChar(100)
set #xpath='node'
select objectData.query('/data/*[local-name() = sql:variable("#xpath")]')
.value('.', 'varchar(100)') as xmldata
from table
and value is selected in the column xmldata. But(!) it requires that the root node is the first value in the query function. The following will not work
declare #xpath VarChar(100)
set #xpath='/data/node'
select objectData.query('*[local-name() = sql:variable("#xpath")]')
.value('.', 'varchar(100)') as xmldata
from table
notice how the query path is "moved up" to the variable. I will continue my investigations..
A literal is the opposite of a variable. The message means that you cannot pass a variable as the first argument to query.
One way around that is dynamic SQL:
declare #sql varchar(max)
set #sql = 'select id from table where xmldata.query(''' + #path +
''').value(''.'', ''VARCHAR(50)'') = ''value'''
exec #sql
As you can see, dynamic SQL does not result in very readable code. I would certainly investigate alternatives.
EDIT: Your suggestion of local-name() works for node names.
declare #nodename varchar(max)
set #nodename = 'node'
...
where xmldata.query('//*[local-name()=sql:variable("#nodename")]')
.value('.', 'varchar(50)') = 'value'
There doesn't seem to be an equivalent for paths.
I am passing a comma-delimited list of values into a stored procedure. I need to execute a query to see if the ID of an entity is in the comma-delimited list. Unfortunately, I think I do not understand something.
When I execute the following stored procedure:
exec dbo.myStoredProcedure #myFilter=N'1, 2, 3, 4'
I receive the following error:
"Conversion failed when converting the varchar value '1, 2, 3, 4' to data type int."
My stored procedure is fairly basic. It looks like this:
CREATE PROCEDURE [dbo].[myStoredProcedure]
#myFilter nvarchar(512) = NULL
AS
SET NOCOUNT ON
BEGIN
-- Remove the quote marks so the filter will work with the "IN" statement
SELECT #myFilter = REPLACE(#myFilter, '''', '')
-- Execute the query
SELECT
t.ID,
t.Name
FROM
MyTable t
WHERE
t.ID IN (#myFilter)
ORDER BY
t.Name
END
How do I use a parameter in a SQL statement as described above? Thank you!
You could make function that takes your parameter, slipts it and returns table with all the numbers in it.
If your are working with lists or arrays in SQL Server, I recommend that you read Erland Sommarskogs wonderful stuff:
Arrays and Lists in SQL Server 2005
You need to split the string and dump it into a temp table. Then you join against the temp table.
There are many examples of this, here is one at random.
http://blogs.microsoft.co.il/blogs/itai/archive/2009/02/01/t-sql-split-function.aspx
Absent a split function, something like this:
CREATE PROCEDURE [dbo].[myStoredProcedure]
#myFilter varchar(512) = NULL -- don't use NVARCHAR for a list of INTs
AS
SET NOCOUNT ON
BEGIN
SELECT
t.ID,
t.Name
FROM
MyTable t
WHERE
CHARINDEX(','+CONVERT(VARCHAR,t.ID)+',',#myFilter) > 0
ORDER BY
t.Name
END
Performance will be poor. A table scan every time. Better to use a split function. See: http://www.sommarskog.se/arrays-in-sql.html
I would create a function that takes your comma delimited string and splits it and returns a single column table variable with each value in its own row. Select that column from the returned table in your IN statement.
I found a cute way of doing this - but it smells a bit.
declare #delimitedlist varchar(8000)
set #delimitedlist = '|1|2|33|11|3134|'
select * from mytable where #delimitedlist like '%|' + cast(id as varchar) + '|%'
So... this will return all records with an id equal to 1, 2, 33, 11, or 3134.
EDIT:
I would also add that this is not vulnerable to SQL injection (whereas dynamic SQL relies on your whitelisting/blacklisting techniques to ensure it isn't vulnerable). It might have a performance hit on large sets of data, but it works and it's secure.
I have a couple of blog posts on this as well, with a lot of interesting followup comments and dialog:
More on splitting lists
Processing list of integers