[英]Rows not being updated
I have written the following function meant to update a student in my database: 我写了以下函数来更新我的数据库中的学生:
public bool UpdateStudent(Student stu)
{
Console.WriteLine("StudentManger.UpdateStudent): Called");
int rowsChanged = 0;
using (var cnn = new SqlConnection(
Properties.Settings.Default.universityConnectionString))
{
using (var cmd = new SqlCommand("UPDATE Student " +
"SET FirstName = @FirstName, " +
"lastName = @LastName, " +
"birth = @birth " +
"WHERE id = @id", cnn))
{
cmd.Parameters.Add(new SqlParameter("@FirstName", stu.FirstName));
cmd.Parameters.Add(new SqlParameter("@LastName", stu.LastName));
cmd.Parameters.Add(new SqlParameter("@id", stu.ID));
cmd.Parameters.Add(new SqlParameter("@birth", stu.Birth));
cnn.Open();
rowsChanged = (int)cmd.ExecuteNonQuery();
Properties.Settings.Default.Save();
}
}
Properties.Settings.Default.Save();
return (rowsChanged != 0);
}
But when I call function no data is actually getting saved to the Database 但是当我调用函数时,没有数据实际上被保存到数据库中
Can someone tell me why? 有人可以告诉我为什么吗?
With the entire solution and information you provided in chat , your code is fine. 使用您在聊天中提供的整个解决方案和信息,您的代码就可以了。 The problem is that the .mdf database file is set to "Copy to Output Directory": "Always" in your project. 问题是.mdf数据库文件设置为“复制到输出目录”:项目中的“始终”。 Change this property to "Copy if newer" (or "Do not copy" and move it to the bin folder yourself) and it will not overwrite your changes when you re-run the application. 将此属性更改为“如果更新则复制”(或“不复制”并自行将其移动到bin文件夹),并且在重新运行应用程序时不会覆盖您的更改。 Importantly, you will not see the changes you make in your application reflected in your .mdf database file in the project's root directory . 重要的是,您不会看到您在应用程序中所做的更改反映在项目根目录中的.mdf数据库文件中 。 It actually gets copied to the /bin folder and that's where the changes are persisted. 它实际上被复制到/ bin文件夹,并且这是持久化更改的位置。 So, if you don't change the "Copy to Output Directory" property, it will copy from your root to your /bin folder every time you build. 因此,如果您不更改“复制到输出目录”属性,则每次构建时它都会从根目录复制到/ bin文件夹。 Thus it appears that the changes aren't being persisted, when they actually are. 因此, 看起来这些变化并没有持续存在,而实际上却是如此。
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