PLS-00306：调用oracle函数时参数的数量或类型错误

Question

I have a simple oracle function as below

create or replace function get_area(
mem_id IN VARCHAR2,
P_date    DATE DEFAULT SYSDATE)
RETURN NUMBER
IS
  v_area_id NUMBER;
BEGIN
v_area_id := 0;
RETURN v_area_id ;
end;

(its a testing function so just assigning 0 and returning back the variable)

We are calling the same in C# as below

            ora_con.Open();
            OracleCommand cmd = ora_con.CreateCommand();
            cmd.CommandType = CommandType.StoredProcedure;
            cmd.Connection = ora_con;

            cmd.CommandText = "schema.get_area";

            OracleParameter mem_id = new OracleParameter();
            mem_id.OracleDbType = OracleDbType.Varchar2;
            mem_id.Direction = ParameterDirection.Input;
            mem_id.Value = m_id1;

            OracleParameter P_date = new OracleParameter();
            P_date.OracleDbType = OracleDbType.Date;
            P_date.Direction = ParameterDirection.Input;
            P_date.Value = DateTime.Now;

            OracleParameter v_area_id = new OracleParameter();
            v_area_id.OracleDbType = OracleDbType.Int64;
            v_area_id.Direction = ParameterDirection.ReturnValue;
            v_area_id.Size = 1000;

            cmd.Parameters.Add(mem_id);
            cmd.Parameters.Add(P_date);
            cmd.Parameters.Add(v_area_id);

            cmd.ExecuteNonQuery();
            area_id = Convert.ToInt64(cmd.Parameters["v_area_id"].Value);

while executing the same getting the below error

ORA-06550: line 1, column 15: PLS-00306: wrong number or types of arguments in call to 'GET_AREA' ORA-06550: line 1, column 7: PL/SQL: Statement ignored

Answer 1

From the docs

https://docs.oracle.com/en/database/oracle/oracle-database/12.2/odpnt/featOraCommand.html#GUID-4D32E59C-1BC0-4567-994E-B0EF3D61D3C4

When binding by position (default) to a function, ODP.NET expects the return value to be bound first, before any other parameters.

so move your return value parameter to be the first one in your list.

Answer 2

As I read in this similar issue , probably you're declaring parameters in wrong order since Oracle stores return value as index 0 inside parameter list and input parameters followed suit.

Try to adjust parameter order so that the return value assigned first, since mem_id has type of VARCHAR2 and incompatible with NUMBER type:

cmd.Parameters.Add(v_area_id); // this should be added first
cmd.Parameters.Add(mem_id);
cmd.Parameters.Add(P_date);