1
我正在试验数据库，我找到了不同的方法来优化我的代码。在这里，我正在使用不同的类来停止重新编写相同的代码，例如添加，删除和更新，我们使用相同的ExecuteNonQuery()方法。到目前为止，更新删除方法运行良好，除了插入。编译器不会给出任何错误，但是从文本框中获取的值不会转到变量字符串查询。我是新来的C＃编码。谁能帮我？或建议？如何将数据插入数据库？ - 用户定义的类
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());
}
}
这是DBComps类以前写SQL函数的方法。
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;
}
}
}
每次调用'dc.ExeNonQuery'时，都会创建一个新的命令实例'com = new SqlCommand（query，con）;'，从而失去了之前添加到以前'com'值的所有参数。最简单的解决方案是每次停止创建新的命令实例，通过设置[命令文本属性]（https://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlcommand.com和text （v = vs.110）.aspx）的现有命令（!!!它可以是空的第一次!!!）。 –
P.S .:当实例方法和静态字段不是实际需要时混合使用它是一个坏主意。此外，[使用]（https://msdn.microsoft.com/en-us/library/yh598w02.aspx）声明可能会对您感兴趣。 –
@EugenePodskal是的，我真的很傻。我删除了所有这些，最后我找到了答案。谢谢您的帮助。 –