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DerekT-P wrote: I'm just surprised there's not more control over serialisation!
That would not help you, since that's not the problem.
DerekT-P wrote: There are use cases where I want certain related objects, and others where I don't. There are multiple combinations of multiple objects. I guess it might be possible to artificially construct classes that have the required lower levels in various combinations, but that would be bringing aspects of user interface design over into the class structure of the business layer
So, you want to religouly adhere to the rules, or do as any game does and break some rules?
Bastard Programmer from Hell 
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.
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I am very new to Asp.Net I am going to study with practical with examples so i need good and easy understanding material for my knowledge development
I am using Visual basic community 2022 and Mysql database
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C#:
Best solution is a course - if you don't understand something, then the tutor can explain in different ways until you do.
Next best is a book - Wrox, Addison Wesley, Microsoft press all do good ones which take you through the whole language, together with the framework behind it (and the framework is HUGE!)
Then there is guesswork: Think of something that might be in the language (or find a chunk of code) and try it. Kick it until it sort of does something. Ineffective and means you miss far, far too much because you don't even know they exist!
Worst of all is YouTube - most of the tutorial content is created by people who don't know how to teach, don;t know how to make a video, and generally don't know how to code. They have a chunk of code that might work, but they have no idea how it does that, and can't actually alter it to do a similar job. Remember, "Likes" and "Subscribes" make you money - and that's why the video is there. They are probably good video tutorials, but they are next to impossible to find becuas etehy are drowned in a sea of dross.
Exactly the same thing applies to MySQL: Course, Book, Guesswork, Youtube.
A C# book will cover a bit of SQL as well, when it talks about Databases - but generic SQL, rather than MySql specific. Much of it is the same, certainly the simple stuff.
Learn C# first, and get confident in your abilities there. Then learn MySql.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
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It shows record updated successfully but not updating in database
private void button13_Click(object sender, EventArgs e)
{
if (textBox6.Text != "" && textBox7.Text != "" && textBox8.Text != "")
{
string connectionString;
MySqlConnection cnn;
connectionString = @"Data Source=localhost;Initial Catalog=testDB;User ID=root;Password=mysql";
cnn = new MySqlConnection(connectionString);
//string id = Convert.ToInt32(textBox6.Text);
string id = textBox6.Text;
string name = textBox7.Text;
string salary = textBox8.Text;
textBox6.Text = "";
textBox7.Text = "";
textBox8.Text = "";
string query = "update employee set employee_id='" + this.textBox6.Text + "',employee_name='" + this.textBox7.Text + "',employee_salary='" + this.textBox8.Text + "' where employee_id='" + this.textBox6.Text + "';";
using (MySqlCommand cmd = new MySqlCommand(query))
{
cmd.Parameters.AddWithValue("@employee_id", id);
cmd.Parameters.AddWithValue("@employee_name", name);
cmd.Parameters.AddWithValue("@employee_salary", salary);
cmd.Connection = cnn;
cnn.Open();
cmd.ExecuteNonQuery();
DialogResult dr = MessageBox.Show("Are you sure to update row?", "Confirmation", MessageBoxButtons.YesNo);
if (dr == DialogResult.Yes)
{
MessageBox.Show("Record Updated Successfully");
cnn.Close();
DisplayData();
ClearData();
}
else if (dr == DialogResult.No)
{
MessageBox.Show("Dude, We keep this record as same");
}
}
}
else
{
MessageBox.Show("Please Select Record to Update");
}
}
modified 20-Mar-22 11:58am.
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Yes sir. Output came. Thanks to all
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Dude.
No.
Please burn it.
Bastard Programmer from Hell
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.
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I thought we discussed this ... your reply less than 5 hours ago was "Ok sir"
Is there any point in us talking to you at all?
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
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if (textBox6.Text != "" && textBox7.Text != "" && textBox8.Text != "") No.
Nuke it from orbit. That's the only way to be sure.
Bastard Programmer from Hell
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.
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I don't think he really wants to learn - just get his homework done for him ... where he can't copy'n'paste a solution.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
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Where would one start? At textBox7, or the missing usings?
I'd burn the code and never look back.
Bastard Programmer from Hell
"If you just follow the bacon Eddy, wherever it leads you, then you won't have to think about politics." -- Some Bell.
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So, it's obvious you're just copying and pasting code from the web and hoping it works. You don't have any idea why there are parameter objects or how they are used in the query.
string query = "update employee set employee_id='" + this.textBox6.Text + "',employee_name='" + this.textBox7.Text + "',employee_salary='" + this.textBox8.Text + "' where employee_id='" + this.textBox6.Text + "';";
using (MySqlCommand cmd = new MySqlCommand(query))
{
cmd.Parameters.AddWithValue("@employee_id", id);
cmd.Parameters.AddWithValue("@employee_name", name);
cmd.Parameters.AddWithValue("@employee_salary", salary);
You're using the TextBox values directly in your query. NEVER DO THIS! User input should be treated like it's the spawn of Satan. Using it directly in your query will lead to SQL Injection Attacks and you risk destroying your database doing that.
Next, you NEVER change or update the value of an ID field in a table. Doing so will destroy your data integrity since records in one table will no longer relate to data in another table.
Your query should look like this (and don't even think of copying and pasting this code!) Try to figure out what the code is doing.
string query = "UPDATE employee SET employee_name=@empName, employee_salary=@empSalary WHERE employee_id=@empId";
using (MySqlCommand cmd = new MySqlCommand(query))
{
cmd.Parameters.AddWithValue("@empId", id);
cmd.Parameters.AddWithValue("@empName", name);
cmd.Parameters.AddWithValue("@empSalary", salary);
I'm ignoring that you're storing salary values as text.
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Noted with thanks. its works
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This could hardly be more wrong
cmd.ExecuteNonQuery();
DialogResult dr = MessageBox.Show("Are you sure to update row?", "Confirmation", MessageBoxButtons.YesNo);
if (dr == DialogResult.Yes)
{
MessageBox.Show("Record Updated Successfully");
You call ExecuteNonQuery but ignore the return value, so if it failsyou will never know. You then ask the user whether to update the row, which (you think) you already did. And if the user answers "Yes", you then post a message to say the update succeeded.
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I seriously doubt it works in all situations. Just because you get a dialog box that says the record is updated, doesn't mean your logic to that point is correct. Given your history, I think it's still very, very wrong.
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if (textBox6.Text!= "" && textBox7.Text != "" && textBox8.Text != "")
{
string connectionString;
MySqlConnection cnn;
connectionString = @"Data Source=localhost;Initial Catalog=testDB;User ID=root;Password=mysql";
cnn = new MySqlConnection(connectionString);
//cnn.Open();
//cnn.Close();
string id = textBox6.Text;
string name = textBox7.Text;
string salary = textBox8.Text;
textBox6.Text = "";
textBox7.Text = "";
textBox8.Text = "";
string query = "delete employee where(@employee_id, @employee_name, @employee_salary)";
using (MySqlCommand cmd = new MySqlCommand(query))
{
cmd.Parameters.AddWithValue("@employee_id", id);
cmd.Parameters.AddWithValue("@employee_name", name);
cmd.Parameters.AddWithValue("@employee_salary", salary);
cmd.Connection = cnn;
cnn.Open();
cmd.ExecuteNonQuery();
MessageBox.Show("Record Deleted Successfully");
cnn.Close();
}
}
else
{
MessageBox.Show("Please Select Record to Delete");
}
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That's not a valid SQL DELETE statement. You're trying telling it to delete the fields in a row and that's not how it works.
The correct format is, assuming your table name is "employee" and the identity column is "EmployeeID":
DELETE employee WHERE EmployeeId = @employee_id
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if change that it tells please select the record...
if (ID != 0)
//if (textBox6.Text!= "" && textBox7.Text != "" && textBox8.Text != "")
{
string connectionString;
MySqlConnection cnn;
connectionString = @"Data Source=localhost;Initial Catalog=testDB;User ID=root;Password=mysql";
cnn = new MySqlConnection(connectionString);
string id = textBox6.Text;
string name = textBox7.Text;
string salary = textBox8.Text;
textBox6.Text = "";
textBox7.Text = "";
textBox8.Text = "";
string query = "DELETE employee WHERE EmployeeId = @employee_id";
using (MySqlCommand cmd = new MySqlCommand(query))
{
cmd.Parameters.AddWithValue("@employee_id", id);
cmd.Parameters.AddWithValue("@employee_name", name);
cmd.Parameters.AddWithValue("@employee_salary", salary);
cmd.Connection = cnn;
cnn.Open();
cmd.ExecuteNonQuery();
MessageBox.Show("Record Deleted Successfully");
cnn.Close();
DisplayData();
ClearData();
}
}
else
{
MessageBox.Show("Please Select Record to Delete");
}
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You just copied and paste code without even trying to understand it.
I told you, I AM ASSUMING TABLE AND COLUMN NAMES!! You have to change those to match what is in your database!
Also, you have to remove the two line that setup Parameters that are not used, "@employee_name" and "@employee_salary".
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DELETE FROM employee WHERE employee_id=@employee_id AND employee_name=@employee_name AND employee_salary-@employee_salary
this code is working but it shows record deleted successfully but in database its not deleted,, what i do?
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