如何在SQL Server中使用'date'数据类型

Question

我目前正在尝试使用Visual Studio在c＃中创建一个asp.net web应用程序。我有一个页面充当父母或孩子的注册页面，具体取决于您选择的单选按钮。注册孩子时，您需要从三个单独的下拉列表中输入DOB。现在，我将DOB数据类型设置为varchar，这意味着05/05/2005的DOB在表中保存为'552005'。

当我的数据类型设置为date或datetime它抛出这个错误：

An exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll but was not handled in user code Additional information: Conversion failed when converting date and/or time from character string.

这是否意味着我必须将字符串解析成一个int某处的代码？如果是这样，我的代码中究竟应该如何以及在哪里？我将包含一些截图以及我的代码。

提前致谢！

Showing how my form looks and how DOB currently stores in table

protected void submitBtn_Click(object sender, EventArgs e) 
{ 
    SqlConnection connect = new SqlConnection("Data Source=THEBEAST;Initial Catalog=newregDB;Integrated Security=True;Pooling=False"); 

    if (parentRadBtn.Checked) 
    { 
     if (firstNameBox.Text == "" || surnameBox.Text == "" || postcodeBox.Text == "" || teleBox.Text == "" || emailBox.Text == "" || userBox.Text == "" || passwordBox.Text == "") 
     { 
      Response.Write("<script>alert('Please ensure all fields have an entry');</script>"); 
      successLabel.Text = (""); 
      userBox.Text = ""; 
      firstNameBox.Text = ""; 
      surnameBox.Text = ""; 
      postcodeBox.Text = ""; 
      teleBox.Text = ""; 
      emailBox.Text = ""; 
      passwordBox.Text = ""; 
     } 
     else 
     { 
      SqlCommand pa = new SqlCommand("INSERT INTO parent(parentID, firstname, surname, postcode, telephone, email, password) VALUES (@parentID, @firstname, @surname, @postcode, @telephone, @email, @password)", connect); 
      pa.Parameters.AddWithValue("@parentID", userBox.Text); 
      pa.Parameters.AddWithValue("@firstname", firstNameBox.Text); 
      pa.Parameters.AddWithValue("@surname", surnameBox.Text); 
      pa.Parameters.AddWithValue("@postcode", postcodeBox.Text); 
      pa.Parameters.AddWithValue("@telephone", teleBox.Text); 
      pa.Parameters.AddWithValue("@email", emailBox.Text); 
      pa.Parameters.AddWithValue("@password", passwordBox.Text); 

      connect.Open(); 
      pa.ExecuteNonQuery(); 
      connect.Close(); 
     } 

     if (IsPostBack) 
     { 
      userBox.Text = ""; 
      firstNameBox.Text = ""; 
      surnameBox.Text = ""; 
      postcodeBox.Text = ""; 
      teleBox.Text = ""; 
      emailBox.Text = ""; 
      passwordBox.Text = ""; 
     } 
    }   
    else if (childRadBtn.Checked) 
    { 
     if (firstNameBox.Text == "" || dayDobList.Text == "" || monthDobList.Text == "" || yearDobList.Text == "" || genderList.Text == "" || userBox.Text == "" || passwordBox.Text == "") 
     { 
      Response.Write("<script>alert('Please ensure all fields have an entry');</script>"); 
      successLabel.Text = (""); 
      userBox.Text = ""; 
      firstNameBox.Text = ""; 
      dayDobList.Text = ""; 
      monthDobList.Text = ""; 
      yearDobList.Text = ""; 
      genderList.Text = ""; 
      passwordBox.Text = ""; 
     } 
     else 
     { 
      SqlCommand ca = new SqlCommand("INSERT INTO children(childID, firstname, dob, gender, password) VALUES (@childID, @firstname, @dob, @gender, @password)", connect); 
      ca.Parameters.AddWithValue("@childID", userBox.Text); 
      ca.Parameters.AddWithValue("@firstname", firstNameBox.Text); 
      ca.Parameters.AddWithValue("@dob", dayDobList.Text + monthDobList.Text + yearDobList.Text); 
      ca.Parameters.AddWithValue("@gender", genderList.Text); 
      ca.Parameters.AddWithValue("@password", passwordBox.Text); 

      connect.Open(); 
      ca.ExecuteNonQuery(); 
      connect.Close(); 
     } 

     if (IsPostBack) 
     { 
      userBox.Text = ""; 
      firstNameBox.Text = ""; 
      dayDobList.Text = ""; 
      monthDobList.Text = ""; 
      yearDobList.Text = ""; 
      genderList.Text = ""; 
      passwordBox.Text = ""; 
     }    
    } 
} 

Answer 1

你的问题是，你必须与旧格式'552005'您的表中的一些数据，所以当你想改变列类型，你会得到错误。所以你有两种选择：

1-从该表中删除任何东西，更改列类型并开始保存日期为datetime或datetime2。

2-将所有当前数据转换为日期字符串，例如。 '05/05/2005 00:00:00'，然后将列类型更改为datetime。

UPDATE：

也不要忘记为数据类型添加到您的SqlParameters：

SqlParameter dob = new SqlParameter("@sinceDateTime", SqlDbType.DateTime); 
dob.Value = new DateTime(Int32.Parse(yearDobList.Text), Int32.Parse(monthDobList.Text), Int32.Parse(dayDobList.Text)); 
ca.Parameters.Add(dob); 

Answer 2

需要一个日期，让日期：

new DateTime(int.Parse(dayDobList.Text), 
      int.Parse(monthDobList.Text), 
      int.Parse(yearDobList.Text))