紧急请教一个C#问题！！！！！！！！！！谢谢啊

private void button1_Click(object sender, EventArgs e)
{
if (textBox1.Text == "" || textBox2.Text == "" || comboBox1.Text == "" || dateTimePicker1.Text == "" || richTextBox1.Text == "" || linkLabel2.Text == "" || textBox4.Text == "")
{
MessageBox.Show("所有项都是必填项,请填完整");
return;
}
string strInsert = "insert into lunwenbiao values('" + textBox4.Text + "','" + textBox1.Text + "','" + textBox2.Text + "','" + comboBox1.Text + "','" + dateTimePicker1.Text + "','" + richTextBox1.Text + "','" + linkLabel2.Text + "')";
string strSql = "select count(*) from lunwenbiao where 论文编号='" + this.textBox4.Text + "'";
String strCon = "Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" + System.Windows.Forms.Application.StartupPath + "\\db2.mdb";
OleDbConnection myConn = new OleDbConnection(strCon);
myConn.Open();
OleDbCommand cmd = new OleDbCommand(strSql, myConn);
int count = Convert.ToInt32(cmd.ExecuteScalar());
if (count > 0)
{
MessageBox.Show("不能添加相同编号的内容");
}
else
{
ExcuteSQL(strInsert);
MessageBox.Show("保存成功");
// this.lunwenbiaoTableAdapter2.Fill(this.db2DataSet2.lunwenbiao);
}
myConn.Close();
}