How to insert data to a database in C#

Question

I've just started to learn about databases and actually I've no idea why the code below doesn't work. I have searched a lot but I didn't realized what exactly is the happening.

I have a Windows Forms app and there are a textbox and a button in it. When I click on the button, the text inside the textbox should get inserted into the database, but nothing is actually happening.

I created the database with Visual Studio. I right-clicked on "Data connections" in Server Explorer in Visual Studio 2019 Community edition and then clicked on "Create New SQL Server Database".

using (SqlConnection con = new SqlConnection("Data Source = (localdb)\\mssqllocaldb; Initial Catalog = myTestDB; Integrated Security = True; Pooling = False")) 
{
    con.Open();

    SqlCommand cmd = new SqlCommand("INSER INTO [tesTable] VALUES (@fname, @lname)", con);

    cmd.Parameters.AddWithValue("@fname", textBox1.Text);
    cmd.Parameters.AddWithValue("@lname", textBox2.Text);
}

MessageBox.Show("done!");

A command needs to be executed before anything happens database side. As a side note, you have used an INSERT command without naming the columns involved. This requires the database table to have exactly the same number of columns in the same exact order in which you add the parameters — Steve
– Steve, Commented Aug 11, 2019 at 8:00
I am suggesting to check the query Sql Profiler after executing your query ,to know the exact query that is being implemented. — sajadre
– sajadre, Commented Aug 11, 2019 at 8:12
You should check out Can we stop using AddWithValue() already? and stop using .AddWithValue() - it can lead to unexpected and surprising results... — marc_s
– marc_s, Commented Aug 11, 2019 at 9:12

Salah Akbari · Accepted Answer · 2019-08-12 03:12:09Z

4

Because you haven't executed your command:

....
cmd.Parameters.AddWithValue("@lname", textBox2.Text);

cmd.ExecuteNonQuery();

The fixed version of your insert statement should be something like this:

"INSERT INTO tesTable (fname,lname) VALUES (@fname,@lname)"

This also needs to be added, that specifying the type directly and use the Value property is more better than AddWithValue:

cmd.Parameters.Add("@lname", SqlDbType.VarChar).Value = textBox2.Text;

Can we stop using AddWithValue() already?

edited Aug 12, 2019 at 3:12

answered Aug 11, 2019 at 7:58

Salah Akbari

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6 Comments

babibooooooo Over a year ago

I did it but I'm getting this error after adding cmd.ExecuteNonQuery();:System.Data.SqlClient.SqlException: 'Incorrect syntax near the keyword 'INTO'.'

babibooooooo Over a year ago

Yes, two columns exactly.

Salah Akbari Over a year ago

@kiarashyoosefi What if you try this: INSERT INTO tesTable (fname,lname) VALUES (@fname,@lname) ? Just make sure the columns in sql are fname and lname exactly as well.

Steve Over a year ago

Notice the typo INSER INTO, missing the T...:-)

Steve Over a year ago

Also that tesTable seems suspect. Probably the OP has a malfunctioning T key.

|

RBT · Accepted Answer · 2022-06-04 05:44:28Z

0

private void btnaddsave_Click(object sender, EventArgs e)
{
    try
    {
        string connection1 = "server=localhost;user id=root;password=1234;database=library_system";
        con = new MySqlConnection(connection1);
        con.Open();
        string q = "Insert Into library_system.add_book(Book_No,Book_Name)values('"+tbbno.Text+"','" + tbbn.Text+ "')";
        cm1 = new MySqlCommand(q, con);
        cm1.ExecuteNonQuery();
        //con.Open();

        MessageBox.Show("data saved", "information", MessageBoxButtons.OK, MessageBoxIcon.Information);
        con.Close();
        // load();
        tbbno.Text = "";
        tbbn.Text = "";
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

edited Jun 4, 2022 at 5:44

RBT

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answered Jun 2, 2022 at 5:48

THARINDU DILSHAN

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