Unable to retrieve next sequence value from a migrated Oracle sequence

Background:

SSMA 4.2 emulates an Oracle sequence as a table containing an IDENTITY column. Each sequence gets its own table, prefaced by the literal “$SSMA_seq_”.    Thus, an Oracle sequence named SUPPLIER_SEQ would be migrated to a table in the target SQL Server database named “$SSMA_seq_SUPPLIER_SEQ”, defined as

CREATE TABLE [dbo].[$SSMA_seq_SUPPLIER_SEQ](

            [id] [numeric](38, 0) IDENTITY(1,1) NOT NULL

) ON [PRIMARY]

SSMA provides a scalar function used to emulate Oracle’s NEXTVAL:

sysdb.ssma_oracle.db_get_next_sequence_value(@dbname,@schema,@name)

Where the arguments are:

• @dbname: The name of the database that contains the sequence.
• @schema: The name of the schema that contains the sequence.
• @name: The sequence name.

Return type: numeric(38,0).

Problem statement:

After migrating an Oracle sequence to SQL Server 2005, the db_get_next_sequence_value UDF unexpectedly returned NULL.

SELECT [sysdb].[ssma_oracle].[db_get_next_sequence_value] (

   N'Scott'

  ,N'dbo'

  ,N'Test')

Returns: NULL

Workaround:

The root cause and a fix for this issue are still under investigation. However, in the interim, we have identified the following workaround.
1) In SQL Server Management Studio, navigate to sysdb, Programmability, Scalar-valued Functions.
2) Right-click the function ssma_oracle.db_get_next_sequence_value and select ‘Modify.’

3) Alter the function to add the highlighted line (shown in context):  

 ALTER function [ssma_oracle].[db_get_next_sequence_value](@dbname sysname,

@schema sysname,

@name sysname) RETURNS integer

as begin

declare @fullname nvarchar(386)

set @fullname = ssma_oracle.db_get_full_name(@dbname,@schema,ssma_oracle.db_get_sequence_table(@name))

if object_id(@fullname) is null return null;

declare @curval integer

declare @spid int, @login_time datetime

select @spid = sysdb.ssma_oracle.get_active_spid(),@login_time = sysdb.ssma_oracle.get_active_login_time()

exec master..xp_ora2ms_exec2 @spid,@login_time,'sysdb','ssma_oracle',

      'db_sp_get_next_sequence_value',@dbname,@schema,@name,@curval output

return @curval

end

The function now returns the correct NEXTVAL for the identity value’s seed and increment:

Author : Brian, SQL Escalation Services , Microsoft