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我正在开发一个 CRUD，每当我尝试升级项目时，它都会向我显示“您的 Sql 语法有错误；请检查与 MariaDB 服务器相对应的手册，以获取正确的语法以在 'Name = as', Last Name 附近使用= 's' WHERE ID = '32' 在第 120 行"

我知道这是一个非常微小的错误，我没有注意到。请帮帮我。

并提前感谢

 public partial class Form1 : Form
{
    static string conString = "datasource=127.0.0.1;port=3306;username=root;password=;database=testc1;";
    MySqlConnection con = new MySqlConnection(conString);
    MySqlCommand cmd;
    MySqlDataAdapter adapter;
    DataTable dt = new DataTable();
    public Form1()
    {
        InitializeComponent();

        //DataGridView Properties
        dataGridView1.ColumnCount = 4;
        dataGridView1.Columns[0].Name = "Id";
        dataGridView1.Columns[1].Name = "First Name";
        dataGridView1.Columns[2].Name = "Last Name";
        dataGridView1.Columns[3].Name = "Address";

        dataGridView1.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.Fill;

        //selection mode
        dataGridView1.SelectionMode = DataGridViewSelectionMode.FullRowSelect;
        dataGridView1.MultiSelect = false;

    }

    // string connectionString = "datasource=127.0.0.1;port=3306;username=root;password=;database=test;";
    //"SELECT * FROM `user1"

    private void Add(string firstname, string lastname, string team)
    {
        //string conString = "datasource=127.0.0.1;port=3306;username=root;password=;database=test;";
        string sql = "INSERT INTO user1(`id`, `first_name`, `last_name`, `address`) VALUES (NULL, '" + textBox1.Text + "', '" + textBox2.Text + "', '" + textBox3.Text + "')";
        cmd = new MySqlCommand(sql, con);

        //Open connection and excute insert
        try
        {
            con.Open();
            if (cmd.ExecuteNonQuery()>=0)
            {
                ClearText();
                MessageBox.Show("Successfully Inserted");
            }

            con.Close();

            Retrieve();
        }
        catch (Exception ex)
        {

            MessageBox.Show(ex.Message);
            con.Close();
        }
    }

    //add to dgview
    private void populate(String id, String first_name, String last_name, String address)
    {
        dataGridView1.Rows.Add(id, first_name, last_name, address);
    }


    //for retrieving from db
    private void Retrieve()
    {
        dataGridView1.Rows.Clear();

        //SQL Statement 
        string sql = "SELECT * FROM `user1`";
        cmd = new MySqlCommand(sql, con);

        //Open con, retrieve, fill DGview
        try
        {
            con.Open();
            adapter = new MySqlDataAdapter(cmd);

            adapter.Fill(dt);

            //loop through dt
            foreach (DataRow row in dt.Rows)
            {
                populate(row[0].ToString(), row[1].ToString(), row[2].ToString(), row[3].ToString());

            }
            con.Close();

            //clear dt

            dt.Rows.Clear();

        }
        catch (Exception ex)
        {

            MessageBox.Show(ex.Message);
            con.Close();
        }
    }

    //update db
    private void Update(int id, string first_name, string last_name, string add)
    {
        //sql stmt
        string sql = "UPDATE user1 first_name = @firstname, last_name = @lastname, add = @address WHERE id = @id";
        cmd = new MySqlCommand(sql, con);
        cmd.Parameters.AddWithValue("@firstname", first_name);
        cmd.Parameters.AddWithValue("@lastname", last_name);
        cmd.Parameters.AddWithValue("@address", add);
        cmd.Parameters.AddWithValue("@id", id);

        //Open con, update, retrieve dgview 
        try
        {

            con.Open();
            adapter = new MySqlDataAdapter(cmd);
            adapter.UpdateCommand = con.CreateCommand();
            adapter.UpdateCommand.CommandText = sql;

            if (adapter.UpdateCommand.ExecuteNonQuery()>= 0)
            {
                ClearText();
                MessageBox.Show("Updated Successfully");
            }

            con.Close();

            Retrieve();
        }
        catch (Exception ex)
        {

            MessageBox.Show(ex.Message);
            con.Close();
        }
    }

    //Deleting Db
    private void Delete(int id)
    {
        //sql stmt
        string sql = "DELETE FROM user1 WHERE ID=" + id + "";
        cmd =  new MySqlCommand(sql, con);

        //open con, excute delete, close con
        try
        {
            con.Open();
            adapter = new MySqlDataAdapter(cmd);
            adapter.DeleteCommand = con.CreateCommand();
            adapter.DeleteCommand.CommandText = sql;

            //promt for confirmation 
            if (MessageBox.Show("Sure??", "Delete", MessageBoxButtons.OKCancel, MessageBoxIcon.Warning)== DialogResult.OK)
            {
                if (cmd.ExecuteNonQuery()>=0)
                {
                    ClearText();
                    MessageBox.Show("Deleted Successfully");
                }
            }


            con.Close();

            Retrieve();
        }
        catch (Exception ex)
        {

            MessageBox.Show(ex.Message);
        }

    }

    //cleat textbox

    private void ClearText()
    {
        textBox1.Text = "";
        textBox2.Text = "";
        textBox3.Text = "";
    }

    private void Form1_Load(object sender, EventArgs e)
    {

    }

    private void dataGridView_MouseClick(object sender, MouseEventArgs e)
    {
        textBox1.Text = dataGridView1.SelectedRows[0].Cells[1].Value.ToString();
        textBox2.Text = dataGridView1.SelectedRows[0].Cells[2].Value.ToString();
        textBox3.Text = dataGridView1.SelectedRows[0].Cells[3].Value.ToString();
    }

    private void Addbtn_Click(object sender, EventArgs e)
    {
        Add(textBox1.Text, textBox2.Text, textBox3.Text);
    }

    private void Retrievebtn_Click(object sender, EventArgs e)
    {
        Retrieve();
    }

    private void Updatebtn_Click(object sender, EventArgs e)
    {
        String selected = dataGridView1.SelectedRows[0].Cells[0].Value.ToString();
        int id = Convert.ToInt32(selected);

        Update(id, textBox1.Text, textBox2.Text, textBox3.Text);
    }

    private void Deletebtn_Click(object sender, EventArgs e)
    {
        String selected = dataGridView1.SelectedRows[0].Cells[0].Value.ToString();
        int id = Convert.ToInt32(selected);

        Delete(id);
    }

    private void Clearbtn_Click(object sender, EventArgs e)
    {
        dataGridView1.Rows.Clear();
    }
}
4

1 回答 1

2

问题的直接原因是ID. 直接的解决方法是添加结束单引号，但更好的解决方法是正确使用准备好的语句：

string sql = "UPDATE user1 `First Name` = @firstname, `Last Name` = @lastname, Address = @address WHERE ID = @id";
cmd = new MySqlCommand(sql, con);
cmd.Parameters.AddWithValue("@firstname", first_name);
cmd.Parameters.AddWithValue("@lastname", last_name);
cmd.Parameters.AddWithValue("@address", add);
cmd.Parameters.AddWithValue("@id", id);

请注意，我还转义了反引号中的First NameandLast Name列，因为它们的名称中有空格。您通常应该避免在表名和列名中使用空格。

您的代码可能还有其他问题，但希望这会为您指明正确的方向。

于 2018-02-18T06:48:37.333 回答