1
我正在試驗數據庫，我找到了不同的方法來優化我的代碼。在這裏，我正在使用不同的類來停止重新編寫相同的代碼，例如添加，刪除和更新，我們使用相同的ExecuteNonQuery()方法。到目前爲止，更新刪除方法運行良好，除了插入。編譯器不會給出任何錯誤，但是從文本框中獲取的值不會轉到變量字符串查詢。我是新來的C＃編碼。誰能幫我？或建議？如何將數據插入數據庫？ - 用戶定義的類
using DBconnectionExercise.DBConnection_Components;
namespace DBconnectionExercise
{
public partial class Student_Form : Form
{
DBComps dc = new DBComps();
//public string constring;
//public SqlConnection con = null;
//public SqlCommand com = null;
public String query;
public Student_Form()
{
InitializeComponent();
//constring = "Data Source=ASHANE-PC\\ASHANESQL;Initial Catalog=SchoolDB;Integrated Security=True";
//con = new SqlConnection(constring);
dc.ConnectDB();
}
private void Form1_Load(object sender, EventArgs e)
{
loadGridData();
}
private void dtp_dob_ValueChanged(object sender, EventArgs e)
{
DateTime Now = DateTime.Today;
DateTime Dob = dtp_dob.Value.Date;
int a = Now.Year - Dob.Year;
if (Now < Dob.AddYears(a)) a--;
tb_Age.Text = a.ToString();
}
private void loadGridData()
{
try
{
query = "Select * from tb_Student";
//dc.OpenCon();
//SqlDataAdapter da = new SqlDataAdapter(query, con);
DataTable dt1 = new DataTable();
dt1 = dc.Data_Table(query);
//da.Fill(dt);
Stu_DataGrid.DataSource = dt1;
//con.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
private void ClearData()
{
tb_Name.Clear();
tb_Address.Clear();
tb_Telno.Clear();
tb_Search.Clear();
tb_Age.Clear();
dtp_dob.Value = DateTime.Today;
}
private void btn_Add_Click(object sender, EventArgs e)
{
try
{
String name = tb_Name.Text;
DateTime dob = dtp_dob.Value.Date;
int age = Convert.ToInt32(tb_Age.Text);
String Address = tb_Address.Text;
int telno = Convert.ToInt32(tb_Telno.Text);
int line = 0;
//con.Open();
query = "Insert into tb_Student values(@Stu_Name, @Stu_DOB, @Age, @Stu_Address, @Stu_Tel_no)";
//query = "Insert into tb_Student (Stu_Name, Stu_DOB, Age, Stu_Address, Stu_Tel_no) Values('" + name + "','" + dob + "','" + age + "','" + Address + "','" + telno + "')";
MessageBox.Show(query);
//com = new SqlCommand(query, con);
// This is the Insert/save code
DBComps.com.Parameters.AddWithValue("@Stu_Name", name);
DBComps.com.Parameters.AddWithValue("@Stu_DOB", dob);
DBComps.com.Parameters.AddWithValue("@Age", age);
DBComps.com.Parameters.AddWithValue("@Stu_Address", Address);
DBComps.com.Parameters.AddWithValue("@Stu_Tel_no", telno);
//line = com.ExecuteNonQuery();
line = dc.ExeNonQuery(query);
//com.Dispose();
//con.Close();
if (line > 0)
{
loadGridData();
ClearData();
MessageBox.Show("Data saved sucessfully!", "Data Saved", MessageBoxButtons.OK, MessageBoxIcon.Information);
}
else
MessageBox.Show("Data not Saved", "Error Save", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
catch(Exception ex)
{
MessageBox.Show(ex.ToString());
}
}
這是DBComps類以前寫SQL函數的方法。
namespace DBconnectionExercise.DBConnection_Components
{
public class DBComps
{
public String conSring;
public SqlConnection con = null;
public static SqlCommand com = null;
public void ConnectDB()
{
conSring = "Data Source=ASHANE-PC\\ASHANESQL;Initial Catalog=SchoolDB;Integrated Security=True";
con = new SqlConnection(conSring);
}
public void OpenCon()
{
con.Open();
}
public void CloseCon()
{
con.Close();
}
public int ExeNonQuery(String query) //the method for Insert, update and delete.
{
int line = 0;
OpenCon();
com = new SqlCommand(query, con);
line = com.ExecuteNonQuery();
com.Dispose();
CloseCon();
return line;
}
}
}
每次調用'dc.ExeNonQuery'時，都會創建一個新的命令實例'com = new SqlCommand（query，con）;'，從而失去了之前添加到以前'com'值的所有參數。最簡單的解決方案是每次停止創建新的命令實例，通過設置[命令文本屬性]（https://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlcommand.com和text （v = vs.110）.aspx）的現有命令（!!!它可以是空的第一次!!!）。 –
P.S .:當實例方法和靜態字段不是實際需要時混合使用它是一個壞主意。此外，[使用]（https://msdn.microsoft.com/en-us/library/yh598w02.aspx）聲明可能會對您感興趣。 –
@EugenePodskal是的，我真的很傻。我刪除了所有這些，最後我找到了答案。謝謝您的幫助。 –