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.
Related
I am looking to get an order number from a column named KEY_Ref, this ref column have various contents, but some rows look like this
LINE_NO=15^ORDER_NO=176572^RELEASE_NO=1^
Now I am interested in getting the value for ORDER_NO (176572 in this case)
How would I (In SQL Server) go about getting this (Or other) value from the main string
The logic is always
key1=value1^key2=value2^key3=value3^
You can use string_split():
select t.*, s.orderno
from t outer apply
(select stuff(s.value, 1, 9, '') as orderno
from string_split(t.key_ref, '^') s
where s.value like 'ORDER_NO=%'
) s;
Here is a db<>fiddle.
this is going to be a bit lengthy answer however if your SQL server version doesn't support string_split function you may use this.
declare #str varchar(100) = 'LINE_NO=15^ORDER_NO=176572^RELEASE_NO=1^'
declare #substr1 varchar(50) = substring(#str,charindex('^',#str)+1,len(#str))
declare #substr2 varchar(50) = substring(#substr1,charindex('=',#substr1)+1,charindex('^',#substr1)-charindex('=',#substr1)-1)
select #substr2 as 'order number'
the final variable will produce the desired value and you must merge the above queries to a single query that can fetch the value from the table in a single select statement.
this will work only if the pattern doesn't deviate from the one you've mentioned.
I have a requirement where I need to check authorization in DB. However the authorization field contains comma-separated values. So, to extract and add a where clause I used CROSS-APPLY, as demonstrated at split-comma-separated-list, which is working fine.
The query goes something like
SELECT EmployeeID,
LTRIM(RTRIM(m.n.value('.[1]','varchar(8000)'))) AS Certs
FROM
(
SELECT EmployeeID,CAST('<XMLRoot><RowData>' + REPLACE(Certs,',','</RowData><RowData>') + '</RowData></XMLRoot>' AS XML) AS x
FROM some_table
)t
CROSS APPLY x.nodes('/XMLRoot/RowData')m(n)
Later I need to get the column "Certs" dynamically from another table. So, I added one more select with it to get the column name. But when I write that in REPLACE function, it returns the value i.e. column name. I need to treat it as a column name and get the values corresponding to it.
The modified query looks like
SELECT EmployeeID,
LTRIM(RTRIM(m.n.value('.[1]','varchar(8000)'))) AS Certs
(SELECT DatabaseColumnName FROM column_name_table WHERE ID = 98) YY ---Returns "Certs"
CROSS APPLY
FROM
(
SELECT EmployeeID,CAST('<XMLRoot><RowData>' + REPLACE(YY.DatabaseColumnName,',','</RowData><RowData>') + '</RowData></XMLRoot>' AS XML) AS x
FROM some_table
)t
CROSS APPLY x.nodes('/XMLRoot/RowData')m(n)
Any help is deeply appreciated!
Repeating my earlier comment: you need to use dynamic sql, and you need to be very careful with dynamic sql to avoid sql injection if this code is exposed to user input.
If the DatabaseColumnName will be the same for all EmployeeID, then you can get that column name and concatenate it to the executed sql like so:
declare #col sysname;
declare #sql nvarchar(max);
select #col = DatabaseColumnName from column_name_table where id = 98);
set #sql = '
SELECT EmployeeID,
LTRIM(RTRIM(m.n.value(''.[1]'',''varchar(8000)''))) AS '+#col+'
FROM
(
SELECT EmployeeID,CAST(''<XMLRoot><RowData>''
+ REPLACE('+#col+','','',''</RowData><RowData>'')
+ ''</RowData></XMLRoot>'' AS XML) AS x
FROM some_table
)t
CROSS APPLY x.nodes(''/XMLRoot/RowData'')m(n)
'
exec sp_executesql #sql;
Dynamic Sql Reference:
The curse and blessings of dynamic SQL - Erland Sommarskog
sp_executesql
If you want more options for splitting strings other than the method you are using now:
Splitting Strings:
Tally OH! An Improved SQL 8K “CSV Splitter” Function - Jeff Moden
Split strings the right way – or the next best way - Aaron Bertrand
Splitting Strings : A Follow-Up - Aaron Bertrand
Splitting Strings : Now with less T-SQL - Aaron Bertrand
string_split() in SQL Server 2016 : Follow-Up #1 - Aaron Bertrand
I'm attempting to validate some column headings before the import of a monthly data set. I've set up an Execute SQL Task that's supposed to retrieve the column headings of the prior month's table and store it in Header_Row as a single string with the field names separated by commas. The query runs just fine in SQL Server, but when running in SSIS, it throws the following error:
"The type of the value (Empty) being assigned to variable 'User:Header_Row' differs from the current variable type (String)."
1) Does this mean that I'm not getting anything back from my query?
2) Is there another method I should be using in SSIS to get the query results I'm looking for?
3) Is there an issue with me using the variable reference in my query as a portion of a string? I think the answer is yes, but would like to confirm, as my variable was still empty after changing this.
Original Query:
SELECT DISTINCT
STUFF((
SELECT
',' + COLUMN_NAME
FROM
db_Analytics.INFORMATION_SCHEMA.COLUMNS aa
WHERE
TABLE_NAME = 'dt_table_?'
ORDER BY
aa.ORDINAL_POSITION
FOR
XML PATH('')
), 1, 1, '') AS Fields
FROM
db_Analytics.INFORMATION_SCHEMA.COLUMNS a;
EDIT: After changing the variable to cover the full table name, I have a new error saying "The value type (__ComObject) can only be converted to variables of the type Object."
Final Query:
SELECT DISTINCT
CAST(STUFF((
SELECT
',' + COLUMN_NAME
FROM
db_Analytics.INFORMATION_SCHEMA.COLUMNS aa
WHERE
TABLE_NAME = ?
ORDER BY
aa.ORDINAL_POSITION
FOR
XML PATH('')
), 1, 1, '') As varchar(8000)) AS Fields
FROM
db_Analytics.INFORMATION_SCHEMA.COLUMNS a;
You are attempting to parameterize your query. Proper query parameterization is useful for avoiding SQL Injection attacks and the like.
Your query is looking for a TABLE_NAME that is literally 'dt_table_?' That's probably not what you want.
For laziness, I'd just rewrite it as
DECLARE #tname sysname = 'dt_table_' + ?;
SELECT DISTINCT
STUFF((
SELECT
',' + COLUMN_NAME
FROM
db_Analytics.INFORMATION_SCHEMA.COLUMNS aa
WHERE
TABLE_NAME = #tname
ORDER BY
aa.ORDINAL_POSITION
FOR
XML PATH('')
), 1, 1, '') AS Fields
FROM
db_Analytics.INFORMATION_SCHEMA.COLUMNS a;
If that's not working, you might need to use an Expression to build out the query.
I'm really pretty sure that this is your problem:
TABLE_NAME = 'dt_table_?'
I'm guessing this is an attempt to parameterize the query, but having the question mark inside the single-quote will cause the question mark to be taken literally.
Try like this instead:
TABLE_NAME = ?
And when you populate the variable that you use as the parameter value, include the 'dt_table_' part in the value of the variable.
EDIT:
Also in your ResultSet assignment, try changing "Fields" to "0" in the Result Name column.
There are two issues with the query above:
1) The query in the task was not properly parameterized. I fixed this by putting the full name of the prior month's table into the variable.
2) The default length of the result was MAX, which was causing an issue when SSIS would try to put it into my variable, Header_Row. I fixed this by casting the result of the query as varchar(8000).
Thanks for the help everyone.
i need to collect all return data into a variable using comma separated.
let say i have a select command like: select * from #temptable.
it's return:
Field1|Field2
-------------
Value1|Value2
Expected Result: #testvariable hold the value: 'Value1','Value2'
On this table their may have 2 columns and i need to store all the return result into a single variable. We can easily collect a single value like: select #var=column1 from #temptable. But i need to store all.Here the problem is, the number of column can be vary. Mean, number of column and name of column generate from another query.So, i can't mention the field name.I need a dynamic way to do it. on this table only one row will be return. Thanks in advance.
You can do this without dynamic SQL using XML
DECLARE #xml XML = (SELECT * FROM #temptable FOR XML PATH(''))
SELECT stuff((SELECT ',' + node.value('.', 'varchar(100)')
FROM #xml.nodes('/*') AS T(node)
FOR XML PATH(''), type).value('.','varchar(max)')
, 1, 1, '');
This can probably be simplified by someone more adept at XML querying than me.
Since your column names are dynamic, so first you have to take the column names as comma separated in a variable and then can use EXEC()
for example :-
//making comma seperated column names from table B
DECLARE #var varchar(1000)=SELECT SUBSTRING(
(SELECT ',' + Colnames
FROM TABLEB
ORDER BY Colnames
FOR XML PATH('')),2,200000)
//Execute the sql statement
EXEC('select '+#var+' from tableA')
if you want to get the value returned after execution of sql statement then you can use
sp_executesql (Transact-SQL)
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