public partial class DAL
    {
        
        private string ConnectionString
        {
            get
            {
                return RAB_UCHET.Properties.Settings.Default.ConnectionString;
            }
        }
        public OracleConnection OracleConnection
        {
            get
            {
                if (this.oracleConnection == null)
                {
                    this.oracleConnection = new OracleConnection(this.ConnectionString);
                    oracleConnection.Unicode = true;
                    oracleConnection.Open();
                }
                
                return this.oracleConnection;
            }
        }
        public void UpdInsQuare(string queryString)
        {
            try{
                OracleCommand command = new OracleCommand(queryString, this.OracleConnection);
                //OracleConnection.Open();
                command.ExecuteNonQuery();
                //OracleConnection.Commit();
                
                queryString = "";
            }
            catch
            {
            }
        }
public bool Commit()
        {
            UpdInsQuare("Commit;");
            return true;
        }
        public bool AddEmployer(Employer emp)
        {
            try
            {
                queryString = "insert into EMPLOYESS(HID,PERSON_NUMBER,SURNAME_EMPLOYER,NAME_EMPLOYER,PATRONOMIC_EMPLOYER,HID_ORGANIZATION,HID_DEPARTMENT,POST,ID_CARD)" +
                    "values(EMPLOYESS_HID.NEXTVAL,'" + emp.PersonNumber +
                    "','"  + emp.SurnameEmployer + "','" + emp.NameEmployer + "','" + emp.PatronomicEmployer +
                    "','" + emp.HID_ORGANIZATION + "','" +  emp.HID_DEPARTMENT + "','" + emp.Post +"','"+emp.ID_Card+"')";

               UpdInsQuare(queryString);
               Commit();
               queryString = "";
            }
            catch
            {
                return false;
            }
            return true;
        }
}

public partial class fNewEmployer : Form
    {
//public Employer NewEmployer { get; private set; }
        DAL dal = new DAL();
        public fNewEmployer()
        {
            InitializeComponent();
        }

        private void bt_save_Click(object sender, EventArgs e)
        {
            if (tb_name.Text.Trim() == string.Empty ||
                tb_surname.Text.Trim() == string.Empty ||
                tb_patronomic.Text.Trim() == string.Empty ||
                tb_personNumber.Text.Trim() == string.Empty ||
                cb_nameOrg.Text.Trim() == string.Empty ||
                cb_nameDep.Text.Trim() == string.Empty ||
                tb_Post.Text.Trim() == string.Empty ||
                tb_idCard.Text.Trim() == string.Empty)
            {
                lb_mess.Text = "Не все поля заполнены.";
                lb_mess.BackColor = Color.Red;
                return;
            }

            dal.AddEmployer(new Employer(string.Empty, tb_personNumber.Text.Trim(), tb_surname.Text.Trim(), tb_name.Text.Trim(), tb_patronomic.Text.Trim(), dal.SelOrg(cb_nameOrg.Text.Trim()),
            dal.SelHidDep(cb_nameDep.Text.Trim()), tb_Post.Text.Trim(), tb_idCard.Text.Trim()));
            DialogResult = DialogResult.OK;
        }
private void fNewEmployer_Load(object sender, EventArgs e)
        {
            cb_nameOrg.Items.Clear();
            foreach (string item in dal.SelNameOrg())
            {
                cb_nameOrg.Items.Add(item);
            }
        }

        private void cb_nameDep_Click(object sender, EventArgs e)
        {
            if (cb_nameOrg.Text.Trim() != string.Empty)
            {
                cb_nameDep.Items.Clear();
                foreach (string item in dal.SelNameDepartaments(cb_nameOrg.Text.Trim()))
                {
                    cb_nameDep.Items.Add(item);
                }
            }
        }
}

У продукта ODAC от DevArt, которым ты пользуешся есть SQL*Monitor. Включи его и посмотри какие команды твоя поделка фигачит.