mysql - C#连接数据库时一直这一句出问题int i = cmd.ExecuteNonQuery();

问题描述

private void button1_Click(object sender, EventArgs e)

{string MyConnectionString = 'server=localhost;user=root;database=yangbo;port=3306;password=yangbo6510;';MySqlConnection connection = new MySqlConnection(MyConnectionString);if (textBox_username.Text.Trim() == '' && textBox_password.Text.Trim() == ''){ MessageBox.Show('请输入用户名和密码进行注册');}else{ connection.Open();//连接到数据库 string sql = 'select * from usernp where username=’' + textBox_username.Text.Trim() + '’ ;'; MySqlCommand cmd = new MySqlCommand(sql, connection); cmd.CommandType = CommandType.Text; MySqlDataReader sdr; sdr = cmd.ExecuteReader(); if (sdr.Read()) {MessageBox.Show('用户名重复，请重新输入');textBox_username.Clear();textBox_password.Clear(); } else {string sql1 = 'insert into usernp (username,userpassword) values(’ + textBox_username.Text.Trim() + ’,’ + textBox_password.Text.Trim() +’)';cmd = new MySqlCommand(sql1, connection);int i = cmd.ExecuteNonQuery();if (i> 0){ MessageBox.Show('注册成功'); textBox_username.Clear(); textBox_password.Clear();}else{ MessageBox.Show('注册不成功'); textBox_username.Clear(); textBox_password.Clear();} } connection.Close();} }

问题解答

你倒是说一下具体出什么问题啊，另外看起来sql1里面的单引号应该改为双引号才是你的本意，但改了后需加上必要的包裹单引号。

首先 请不要拼接sql，其次用sqlparameter

sql拼接错了