Updating database from multiple textboxes

Question

this is my code for an update button which is supposed to update the database based on entry values of textboxes.I made the textboxes to be filled when user selects a row on datagridview.I want the user to simply click the row then change the textbox texts then click update.But i can't get this to work.All comments are helpful.Shoot.

private void btnUpdate_Click(object sender, EventArgs e)
    {
        try
        {
            if (txtOgrenciNo.Text.Length != 0 && txtAd.Text.Length != 0 && txtSoyad.Text.Length != 0 && txtEmail.Text.Length != 0 && txtTelefon.Text.Length != 0)
            {
                string query ="UPDATE ogrenci(studentId,name,lname,email,phone) SET (studentId=@studentId,name@name,lname=@lname,email=@email,phone=@phone) WHERE studentId=@studentId";
                string query1 = "UPDATE loginusers(username,upassword) SET (username=@email,upassword=@phone) WHERE username=@email";
                using (connection = new SqlConnection(connectionString))
                using (SqlCommand command = new SqlCommand(query, connection))
                using (SqlCommand cmd = new SqlCommand(query1, connection))
                {
                    connection.Open();
                    cmd.Parameters.AddWithValue("@emailVal", txtEmail.Text);
                    cmd.Parameters.AddWithValue("@phone", txtPhone.Text);
                    command.Parameters.AddWithValue("@studentId", txtStudentId.Text);
                    command.Parameters.AddWithValue("@name", txtName.Text);
                    command.Parameters.AddWithValue("@lname", txtLname.Text);
                    command.Parameters.AddWithValue("@email", txtEmail.Text);
                    command.Parameters.AddWithValue("@phone", txtPhone.Text);
                    cmd.ExecuteNonQuery();
                    command.ExecuteNonQuery();
                    populateGrid();
                }
            }
            else
            {
                MessageBox.Show("Student Information can not be blank","Alert",MessageBoxButtons.OK,MessageBoxIcon.Information);
            }
        }
        catch (Exception)
        {
            MessageBox.Show("Please enter different student info", "Alert", MessageBoxButtons.OK, MessageBoxIcon.Information);
        }
    }

i use a similar code for add button which has INSERT instead of UPDATE in queries and it works perfectly. — Poyraz Kürkçüoğlu
– Poyraz Kürkçüoğlu, Commented Feb 3, 2017 at 8:04
and I think when you insert there is only one query? Am I right? — kgzdev
– kgzdev, Commented Feb 3, 2017 at 8:05
Seems that you don't provide parameters under this block: using (SqlCommand command = new SqlCommand(query, connection)). SQL queries requires parameter for each execution even the parameters are same, and should be evaluated one-by-one. — Tetsuya Yamamoto
– Tetsuya Yamamoto, Commented Feb 3, 2017 at 8:05
@IkramTurgunbaev there ıs two queries one for students and one for loginusers. — Poyraz Kürkçüoğlu
– Poyraz Kürkçüoğlu, Commented Feb 3, 2017 at 8:14

kgzdev · Accepted Answer · 2017-02-03 08:23:28Z

2

Change your update queries, remove (parameters) after table name

Change this lines

string query ="UPDATE ogrenci(studentId,name,lname,email,phone) SET (studentId=@studentId,name@name,lname=@lname,email=@email,phone=@phone) WHERE studentId=@studentId";
string query1 = "UPDATE loginusers(username,upassword) SET (username=@email,upassword=@phone) WHERE username=@email";

To this

string query ="UPDATE ogrenci SET  studentId=@studentId,name@name,lname=@lname,email=@email,phone=@phone WHERE studentId=@studentId";
string query1 = "UPDATE loginusers SET username=@email,upassword=@phone WHERE username=@email";

edited Feb 3, 2017 at 8:23

answered Feb 3, 2017 at 8:08

kgzdev

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2 Comments

Poyraz Kürkçüoğlu Over a year ago

one more question i can update name lname email but when i try to update phone number it conflicts with the foreign key it says do you know a way around this ?

kgzdev Over a year ago

Your phone column references primary key column on another table, so your new updated value should exist on another table, if not it raises error you show. For more info look this - Foreign Keys Oluşturma

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