create or replace procedure JOB_EDIT (
v_job_id in jobs.job_id%type, 
v_job_title in jobs.job_title%type,
v_min_salary in jobs.min_salary%type:=null,
v_max_salary in jobs.max_salary%type:=null
) 
is
begin
....

OracleConnection conn = null;
OracleTransaction tran=null;
try {
conn = new OracleConnection( ...here my connection string ... );

string strCmd = "begin job_edit(:v_job_id, :v_job_title, :v_min_salary, :v_max_salary); end;";

OracleCommand cmd = new OracleCommand(strCmd, conn);
cmd.Parameters.Add(new OracleParameter(":v_job_id", OracleType.VarChar,  10 )).Value = jobRow.JOB_ID;
cmd.Parameters.Add(new OracleParameter(":v_job_title", OracleType.VarChar,  35 )).Value = jobRow.JOB_TITLE;

// Что надо тут присвоить параметрам v_min_salary и v_max_salary ?

conn.Open();
cmd.Transaction = tran = conn.BeginTransaction();
cmd.ExecuteNonQuery();
tran.Commit();
}
catch (OracleException ex) {
// here OracleException: "ORA-01008: not all variables bound"
tran.Rollback();
}
catch (Exception ex) {
tran.Rollback();
}
finally {
conn.Close();
}

OracleConnection conn = null;
OracleTransaction tran=null;
try {
   conn = new OracleConnection( ...here my connection string ... );
   OracleCommand cmd = new OracleCommand("job_edit", conn);
   cmd.CommandType = CommandType.StoredProcedure;

   cmd.Parameters.Add(new OracleParameter("v_job_id", OracleType.VarChar,  10 )).Value = jobRow.JOB_ID;
   cmd.Parameters.Add(new OracleParameter("v_job_title", OracleType.VarChar,  35 )).Value = jobRow.JOB_TITLE;

   // Параметры со значениями по умолчанию не надо вовсе добавлять.

   conn.Open();
   cmd.Transaction = tran = conn.BeginTransaction();
   cmd.ExecuteNonQuery();
   tran.Commit();