Getting a Sequence back from an S-P with typed DataSet problem

Question

Hi,
I know there are loads of topics about sequences on this forum, but I can't seem to find this exact issue amongst them.
As a learning exercise, I've created a typed dataset based on the HR sample database tables Departments and Employees (through the use of the hack to get an OracleDataAdapter to generate typed datasets).
I currently have a problem with retrieving the new sequence value from the 'Insert_Department' stored procedure I've written, and the best thing I can figure is that there is a clash occurring between the type and size of the sequence and the size of the department_id column (number(4) - which maps in .Net to an int16).
The exception I get on running the dataAdapter.Update() method is:
Unable to cast object of type 'Oracle.DataAccess.Types.OracleDecimal' to type 'System.IConvertible'. Couldn't store <330> in DEPARTMENT_ID Column. Expected type is Int16
The record does get inserted into the database ok - therefore I infer that this is a problem with the handling of the return value back to the DepartmentsDataSet column.
My stored procedure is as follows:
PROCEDURE "INSERT_DEPARTMENT" (
"NEW_DEPARTMENT_ID" OUT DEPARTMENTS.DEPARTMENT_ID%TYPE,
"NEW_DEPARTMENT_NAME" IN VARCHAR2,
"NEW_MANAGER_ID" IN NUMBER,
"NEW_LOCATION_ID" IN NUMBER) IS
BEGIN
INSERT INTO DEPARTMENTS(DEPARTMENT_ID, DEPARTMENT_NAME, MANAGER_ID, LOCATION_ID)
VALUES (DEPARTMENTS_SEQ.NEXTVAL, NEW_DEPARTMENT_NAME, NEW_MANAGER_ID, NEW_LOCATION_ID);
SELECT DEPARTMENTS_SEQ.CURRVAL INTO NEW_DEPARTMENT_ID
FROM DUAL;
END "INSERT_DEPARTMENT";
I've tried lots of different things here; I started declaring the parameter as a NUMBER, now it's set to a %TYPE on the column as you can see... and I've also tried assigning the NEXTVAL to a NUMBER(4) local variable before assigning it to the OUT parameter.
Here's the C# that configures the insert command:
// Insert - note that department_id param is an output param
OracleCommand insert = new OracleCommand("odp_hr_dal.insert_department", connection);
insert.CommandType = CommandType.StoredProcedure;
insert.Parameters.Add(new OracleParameter("new_department_id", OracleDbType.Int16, 2, "department_id"));
insert.Parameters["new_department_id"].Direction = ParameterDirection.Output;
insert.Parameters.Add(new OracleParameter("new_department_name", OracleDbType.Varchar2, 30, "department_name"));
insert.Parameters.Add(new OracleParameter("new_manager_id", OracleDbType.Int32, 4, "manager_id"));
insert.Parameters.Add(new OracleParameter("new_location_id", OracleDbType.Int32, 4, "location_id"));
deptDataAdapter.InsertCommand = insert;
The key line is the adding of the "new_department_id" line where I have tried many different types in the vain hope that I can somehow override the conversion process to not think it needs to go as large as a Decimal type.
I wonder if anyone could help point me towards the (probably obvious) thing that I am missing? I've run out of ideas on things to try!
With Best Regards,
Nij

Answer 1

Thank you muylaerk,
That did work.
However, this and the related link you posted raise a question: Given that (in the case of Decimal types) whichever of the DbType or OracleDbType property you set, the other value is set to Decimal also... what setting in the OracleParameter records which was the 'set' property, and therefore, which type will the Value be set to?
In other words, does anything visibly change in the debugger view of the OracleParameter type to see this?
Nij