Oracle function exchange for SQL Server - sql-server

Question

I do an Oracle to SQL Server project，now I have a function that I can not rebuild，I don't know what is wrong，
The function is used to fetch the Oracle sequenes，the result is wrong.
Oracle function code
CREATE FUNCTION [test].[GETWORKORDERID] (numberPre varchar2)
return varchar2 is
PRAGMA AUTONOMOUS_TRANSACTION;
findId number(8); --maxid
nowNumber varchar2(50);
n_count number(8);
n_count2 number(8);
nowNumber2 varchar2(50);
begin
nowNumber := to_char(sysdate, 'yyyymmdd');
nowNumber2 := to_char(sysdate - 1, 'yyyymmdd');
select count(1)
into n_count2
from user_sequences t
where t.sequence_name = 'SEQ_' || numberPre || '_' || nowNumber2;
if n_count2 > 0 then
execute immediate 'drop sequence SEQ_' || numberPre || '_' ||
nowNumber2;
end if;
select count(1)
into n_count
from user_sequences t
where t.sequence_name = 'SEQ_' || numberPre || '_' || nowNumber;
if n_count = 0 then
execute immediate 'create sequence SEQ_' || numberPre || '_' ||
nowNumber ||
' minvalue 10000 maxvalue 99999999 start with 10000 increment by 1 NOCYCLE NOCACHE';
end if;
execute immediate 'select SEQ_' || numberPre || '_' || nowNumber ||
'.nextval from dual'
into findId;
commit;
return numberPre || nowNumber || findId;
end;**
I changed it for SQL Server to：
CREATE FUNCTION [test-CSR].[GETWORKORDERID]
(#numberPre nvarchar(max))
RETURNS TABLE
AS
BEGIN
DECLARE #findId bigint;
DECLARE #nowNumber bigint;
DECLARE #n_count bigint;
DECLARE #n_count2 bigint;
DECLARE #nowNumber2 bigint;
DECLARE #sql1 nvarchar(max);
DECLARE #sql2 nvarchar(max);
DECLARE #sql3 nvarchar(max);
DECLARE #sql4 nvarchar(max);
DECLARE #result nvarchar(max);
SET #nowNumber = CONVERT(varchar(30), GETDATE(), 20)
SET #nowNumber2 = CONVERT(varchar(30), GETDATE(), 20)
SELECT COUNT(1)
INTO n_count2
FROM user_sequences t
WHERE t.sequence_name = 'SEQ_' + numberPre + '_' + nowNumber2;
IF n_count2 > 0
BEGIN
SET #sql1 = 'drop sequence SEQ_' + numberPre + '_' + nowNumber2;
EXECUTE (#sql1)
END;
SELECT COUNT(1)
INTO n_count
FROM user_sequences t
WHERE t.sequence_name = 'SEQ_' + #numberPre + '_' + #nowNumber;
IF n_count = 0
BEGIN
SET #sql2 = 'create sequence SEQ_ ' + #numberPre + '_' + #nowNumber +
' minvalue 10000 maxvalue 99999999 start with 10000 increment by 1 NOCYCLE NOCACHE';
EXECUTE (#sql2)
END;
SET #sql3 = 'select SEQ_ ' + #numberPre + '_' + #nowNumber + '.NEXT VALUE FOR user_sequences';
SET #findId = #sql3;
SET #sql4 = #numberPre + #nowNumber + #findId;
INSERT INTO #result
EXEC (#sql4)
END;
Now I rebuild the function in SQL Server，but when SQL Server runs, the result is wrong， I don't know what the mistake is?

Answer 1

In functions you can not use EXECUTE. You try to create sequence. Functions in SQL Server are pure. They can not change objects and data in the database. I can suggest you to use a PROCEDURE instead of a FUNCTION.
If you declare a FUNCTION, it should be defined like this:
CREATE FUNCTION [test-CSR].[GETWORKORDERID]
(#numberPre nvarchar(max))
RETURNS #result TABLE (...)
AS
BEGIN
...
RETURN;
END
You should save count into variable like this:
SELECT #n_count2 = COUNT(1)
FROM user_sequences t
WHERE t.sequence_name = 'SEQ_' + numberPre + '_' + nowNumber2;
And then write:
IF #n_count2 > 0 ...
At the end you should remove INSERT INTO #result. Should be presented only EXEC (#sql4)
Hope, It can help you.

Answer 2

You'll have to change this to a procedure, if at all possible. There are some not-so-nice ways to run side-effecting functions in SQL Server, but they should be avoided. Check out the automatic translation that SQL Server Migration Assistant for Oracle for gory details.
Normally you should migrate to do things the "SQL Server way" when porting code.
Anyway, here's a idiomatic SQL Server translation of that procedure. But the whole process of dropping sequences is pretty strange.
--create schema [test-CSR]
go
CREATE or alter procedure [test-CSR].[GETWORKORDERID] #numberPre nvarchar(max), #result nvarchar(max) out
AS
/*
declare #result nvarchar(max)
exec [test-CSR].[GETWORKORDERID] N'foo', #result out
print #result
*/
BEGIN
DECLARE #findId bigint;
DECLARE #nowNumber bigint = CONVERT(varchar(30), GETDATE(), 112);
DECLARE #nowNumber2 bigint = CONVERT(varchar(30), GETDATE()-1, 112);
DECLARE #sql nvarchar(max);
declare #seq sysname = concat('SEQ_', #numberPre, '_', #nowNumber);
declare #seq2 sysname = concat('SEQ_', #numberPre, '_', #nowNumber2);
IF exists (select * from sys.sequences where name = #seq2)
BEGIN
SET #sql = concat('drop sequence ', quotename(#seq2));
--print #sql;
EXECUTE (#sql);
END;
IF not exists (select * from sys.sequences where name = #seq)
BEGIN
SET #sql = concat('create sequence ', quotename(#seq),
' start with 10000 increment by 1 minvalue 10000 maxvalue 99999999 NO CYCLE NO CACHE');
--print #sql;
EXECUTE (#sql)
END;
SET #sql = concat('select #findId = NEXT VALUE FOR ', quotename(#seq)) ;
--print #sql;
exec sp_executesql #sql, N'#findId bigint out', #findId = #findId out;
set #result = concat(#numberPre, #nowNumber, #findId);
END;
If you can make the change I would probably have a single sequence object, and pass the next value for that into a function like this:
create sequence WORKORDERID_seq start with 10000 increment by 1 minvalue 10000 maxvalue 99999999 NO CYCLE NO CACHE
go
create function [test-CSR].[GETWORKORDERID2] (#nowNumber nvarchar(max), #nv int)
returns nvarchar(max)
as
begin
return concat(CONVERT(varchar(30), GETDATE(), 112),#nowNumber,#nv)
end
and run a batch job to reset the sequence value every night.