I have the following working DB2 SQL function
CREATE OR REPLACE FUNCTION selector (param VARCHAR(3))
RETURNS TABLE (id INT, CMD VARCHAR(1024), ATTR CHAR(10))
LANGUAGE SQL
DETERMINISTIC
NO EXTERNAL ACTION
RETURN
SELECT id, cmd, attr
FROM test.commandtbl c
WHERE c.attr=param;
Calling it like:
select * from table (selector('c'))!
The problem is that I want the return table to be dynamic in size and type.
I want to use the function with a lot of return fields and and while testing I don't want to always check the return table it everything still matches.
For example:
Test1 is with 5 return columns: INT, INT, INT, CHAR(10), VARCHAR(100)
Test2 is with 20 return columns: 10 VARCHAR(100) and 10 INT
and so on.
Is there a way to do that?
You can consider SQL a statically typed language in that it has little ability to discover its variable (e.g. column) and object (e.g. result set) data types at run time; you have to declare types at the statement compilation time. In other words, what you want to achieve is not possible.
There is a concept of a generic table function which allows you to define a Java-based UDF that returns some result set:
CREATE FUNCTION selector (param VARCHAR(3))
RETURNS GENERIC TABLE
EXTERNAL NAME...
However, you still need to declare the result set structure on the receiving end:
SELECT t.* FROM TABLE (selector('c')) AS t (foo INT, bar INT, baz VARCHAR(10)...)
Related
I need to create a SQL Server TVF that takes a single param and then used that param to build the other required parameters. Is this even possible?
The error states incorrect syntax near 'LEFT'. Simple representation below.
CREATE FUNCTION TESTFUNCTION
(
-- Add the parameters for the function here
#PRM1 VARCHAR(2) = 'ABC',
#PRM2 VARCHAR(1) = LEFT(#PRM1,1)
)
RETURNS TABLE
AS
RETURN
(
-- Add the SELECT statement with parameter references here
SELECT #PRM2
)
GO
Thank You!
BEFORE EDIT MADE IN THE QUESTION :
You need only one parameters :
SELECT #PRM2 = LEFT(#PRM1, 1);
However, you need scaler function not table valued function :
CREATE FUNCTION TESTFUNCTION
(
-- Add the parameters for the function here
#PRM1 VARCHAR(2) = 'ABC'
)
RETURNS VARCHAR(255)
AS
BEGIN
DECLARE #PRM2 VARCHAR(255)
SET #PRM2 = LEFT(#PRM1, 1)
RETURNS (#PRM2)
END
Note : Your #PRM1 will accept only two characters which are AB. So, define appropriate length.
How do I pass multiple entries through an input parameter mapped from a Table Function in SAP HANA ?
I've written a Table Function with an Input Parameter say IN_FORMAT_CD.
I've mapped this parameter to the one created in my calculation view.
I'm able to retrieve the data when I'm passing only one value say 100.
But it gives no result when I'm passing more than one value.
Is there any workaround for the same ?
My table function :
FUNCTION "HADMIN"."RA.Test.Prathamesh::PH_DEMO" (IN IN_FORMAT_CD NVARCHAR(500))
RETURNS TABLE (NAME NVARCHAR(10), ID NVARCHAR(10), FORMAT_CD NVARCHAR(3))
LANGUAGE SQLSCRIPT
SQL SECURITY INVOKER AS
BEGIN
RETURN
SELECT NAME,ID,FORMAT_CD
FROM
HADMIN.PH_DEMO
WHERE FORMAT_CD IN (select :IN_FORMAT_CD as FORMAT_CD from dummy);
END;
What you are looking for is the APPLY_FILTER function of SAP HANA SQLScript.
The following example shows how your scenario could be coded:
create function get_vals (IN id_list varchar(400))
returns table (id bigint, val varchar(40))
as
begin
declare myfilter varchar(450) := ' ID in (' || :id_list || ')';
_tmp = select id, val from some_vals;
_tmp2 = APPLY_FILTER (:_tmp, :myfilter);
return :_tmp2;
end;
select *
from
get_vals ('1, 4, 23, 4, 23, 3');
This approach will push down the unique list of IDs to be used as a filter when reading the table data. However, this is still dynamic SQL so you lose benefits like plan sharing and risk SQL injection attacks. Read more on this e.g. here.
If possible, you want to handle selection lists in your application code.
This, in turn, would also give you the option to decide whether using IN-lists or inner joins against temporary tables is the best approach for your situation.
In case you want to go with the selection list as a string, you should at least make sure, that common SQL injection attacks are not used and that the "in-list" really only contains possible ID values and commas.
it is not possible to produce(!) many items from a single sql variable unless you split them
In your SQL subselect query will return only rows that FORMAT_CD column values are exactly same with IN_FORMAT_CD parameter.
If this parameter represents more than one value, then this parameter is a concatenated string representation of each sub items. So we can split them back.
Splitting will produce a table on the fly which can be used for selection.
Please create the user-defined HANA Split function fnsplit that source codes can be found at referenced document
Then you can alter your function as follows assuming that each value is seperated with "," from others
ALTER FUNCTION "HADMIN"."RA.Test.Prathamesh::PH_DEMO" (IN IN_FORMAT_CD NVARCHAR(500))
RETURNS TABLE (NAME NVARCHAR(10), ID NVARCHAR(10), FORMAT_CD NVARCHAR(3))
LANGUAGE SQLSCRIPT
SQL SECURITY INVOKER AS
BEGIN
RETURN
SELECT NAME,ID,FORMAT_CD
FROM
HADMIN.PH_DEMO
WHERE FORMAT_CD IN (
select str from fnsplit(:IN_FORMAT_CD,',')
);
END;
In a SQL Server database, one can use table variables like this:
declare #table as table (a int)
In an Azure Data Warehouse, that throws an error.
Parse error at line: 1, column: 19: Incorrect syntax near 'table'
In an Azure Data Warehouse, you can use temporary tables:
create table #table (a int)
but not inside functions.
Msg 2772, Level 16, State 1, Line 6 Cannot access temporary tables
from within a function.
This document from Microsoft says,
◦Must be declared in two steps (rather than inline): ◾CREATE TYPE
my_type AS TABLE ...; , then ◾DECLARE #mytablevariable my_type;.
But when I try this:
create type t as table (a int);
drop type t;
I get this :
Msg 103010, Level 16, State 1, Line 1 Parse error at line: 1, column:
8: Incorrect syntax near 'type'.
My objective is to have a function in an Azure Data Warehouse which uses a temporary table. Is it achievable?
Edit Start Here
Note that I am not looking for other ways to create one specific function. I have actually done that and moved on. I'm a veteran programmer but an Azure Data Warehouse rookie. I want to know if it's possible to incorporate some concept of temporary tables in an Azure Data Warehouse function.
Ok, I believe this is what you are after.
Firstly, this uses a Table Value Function, which are significantly faster than Scalar or Multi-statement Table value Functions.
Secondly, there was no use for a Table Variable, or Temporary Table, just some good odd string manipulation, a bit of maths, and a CTE. Definitely no expensive WHILE loop.
I've tested this against the examples in the link, and they all return the expected values.
USE Sandbox;
GO
CREATE FUNCTION ValidateHealthNumber (#HealthNumber varchar(10))
RETURNS TABLE
AS
RETURN
WITH Doubles AS(
SELECT CONVERT(tinyint,SUBSTRING(V.HN,O.P,1)) AS HNDigit,
CONVERT(tinyint,SUBSTRING(V.HN,O.P,1)) * CASE WHEN O.P % 2 = 0 THEN 1 ELSE 2 END ToAdd
FROM (VALUES(#HealthNumber)) V(HN)
CROSS APPLY (VALUES (1),(2),(3),(4),(5),(6),(7),(8),(9)) O(P)),
Parts AS (
SELECT CONVERT(tinyint,SUBSTRING(CONVERT(varchar(2),ToAdd),1,1)) AS FirstDigit, --We know that the highest value can be 18 (2*9)
CONVERT(tinyint,SUBSTRING(CONVERT(varchar(2),ToAdd),2,1)) AS SecondDigit --so no need for more than 2 digits.
FROM Doubles)
SELECT CASE RIGHT(#HealthNumber, 1) WHEN 10 - RIGHT(SUM(FirstDigit + SecondDigit),1) THEN 1 ELSE 0 END AS IsValid
FROM Parts;
GO
CREATE TABLE #Sample(HealthNumber varchar(10));
INSERT INTO #Sample
VALUES ('9876543217'), --Sample
('5322369835'), --Valid
('7089771195'), --Valid
('8108876957'), --Valid
('4395667779'), --Valid
('6983806917'), --Valid
('2790412845'), --not Valid
('5762696912'); --not Valid
SELECT *
FROM #Sample S
CROSS APPLY ValidateHealthNumber(HealthNumber) VHN;
GO
DROP TABLE #Sample
DROP FUNCTION ValidateHealthNumber;
If you don't understand any of this, please do ask.
No you can't. Object can't be created inside User Defined Functions (UDF). Use table variables instead.
If you want yo use user defined type, first create it outside the UDF and use it as a variable type within the UDF.
-- Create the data type
CREATE TYPE TestType AS TABLE
(
Id INT NOT NULL,
Col1 VARCHAR(20) NOT NULL)
GO
-- Create the tabled valued function
CREATE FUNCTION TestFunction
()
RETURNS
#Results TABLE
(Result1 INT, Result2 INT)
AS
BEGIN
-- Fill the table variable with the rows for your result set
DECLARE #Var1 TestType;
RETURN
END
GO
As far as I know, we can return a table as a result of a db function:
CREATE FUNCTION MyFunction(#Value varchar(100))
RETURNS table
AS RETURN (select * from MyTable where ColumnName = '#Value')
in this example we can make the column name as a parameter for the function. My question is, can we write the column name and table name as a parameter for the function? hence we can write a more generic function something like:
CREATE FUNCTION MyGenericSearchFunction(#TableName varchar(100), #ColumnName varchar(100), #Value varchar(100))
RETURNS table
AS RETURN (select * from #TableName where #ColumnName = '#Value')
No, you can't.
This would then be a dynamic query.
For dynamic queries in SQL Server, one has to use exec() or sp_executesql() functions, which are not allowed in functions.
Is it possible to return or output a #tableVariable in SQL Server?
For example for the following stored procedure, how do I return the #TSV table variable?
ALTER PROCEDURE MyStoredProdecure
#Parameter1 INT,
#Parameter2 INT
AS
BEGIN
DECLARE #TSV TABLE
(
Transition_Set_Variable_ID INT,
Passed BIT
)
INSERT INTO #TSV
{ some data }
END
You cannot do it directly. Table variables are valid for READONLY input.
If you have no other data being returned from the stored procedure, you can select from the #TSV at the end and have the caller capture the output, e.g.
ALTER PROCEDURE MyStoredProdecure
#Parameter1 INT,
#Parameter2 INT
AS
BEGIN
DECLARE #TSV TABLE
(
Transition_Set_Variable_ID INT,
Passed BIT
)
INSERT INTO #TSV
{ some data }
SELECT * FROM #TSV
END
Caller
DECLARE #outerTSV TABLE
(
Transition_Set_Variable_ID INT,
Passed BIT
);
insert into #outerTSV
exec MyStoredProdecure 1, 2;
Alternatively, if the SP is really as simple as you showed, turn it into a table valued function instead.
No, but you can write a table valued function that returns a table.
create function MyTVF
#Parameter1 INT,
#Parameter2 INT
returns #tsv table
(
Transition_Set_Variable_ID INT,
Passed BIT
)
AS
BEGIN
INSERT INTO #TSV
{ some data }
return
END
Table Valued Parameters can only be used for input only, not output.
Depending on what your end goal is, here are some options:
change the sproc to a table-valued function to return a TABLE, that can then be used inline in another statement
simply SELECT the data from the #TSV table var at the end of your sproc
return an XML OUTPUT parameter (get a grubby feeling suggesting this, but just to highlight one way to return multiple rows actually using an OUTPUT parameter)
If you go for a Table Valued Function, ideally create an inline one if it is simple as it looks in your case:
e.g.
CREATE FUNCTION dbo.Func()
RETURNS TABLE
AS
RETURN
(
SELECT Something
FROM Somewhere
WHERE x = 1
)