需要帮助更改旧的用户名和密码.. c＃

问题描述

你好..我还是新手..但我需要帮助..我想将旧的用户名和密码更改为新的...



i am使用mysql数据库..



i想在textbox1和textbox2中输入我的旧用户名和密码..



更新文本框3和文本框4中的用户名和密码..



只有一个按钮是更新按钮..



i尝试了但是当我点击更新按钮时一切都改变了..我只想更新特定的旧用户名和密码..



tq in提前



这是我的编码，...我知道根据我的编码，它将更改所有用户名和密码..但我不知道..我真的需要帮助.. tq

hello.. i am still a newbie.. but i need help.. i want to change old username and password to a new one..

i am using mysql database..

i want to enter my old username and password in textbox1 and textbox2..

the update username and password in textbox3 and textbox4..

and only one button which is update button..

i did try it but everything changed when i clicked the update button.. i only wanted the specific old username and password to be update..

tq in advance

this is my coding,.. i know based on my coding it will changed all username and password.. but i did not have any idea.. i really need help.. tq

private void button1_Click(object sender, EventArgs e)
        {
            string constring = "datasource=localhost; port=3306;username=root;password=";
         
            string Query = "update login.database set  username='" + this.textBox3.Text + "', password= '" + this.textBox4.Text + "';"; // to insert data to database
            MySqlConnection conDataBase = new MySqlConnection(constring);
            MySqlCommand cmdDataBase = new MySqlCommand(Query, conDataBase);
            MySqlDataReader myReader;

            try
            {
                conDataBase.Open();
                myReader = cmdDataBase.ExecuteReader();
                MessageBox.Show("Update");
                while (myReader.Read())
                {

                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.Message);
            }

推荐答案

You just missed the condition only as per krunal Rohit the query needs a condition for update data otherwise it will affect all rows of table.

For this You design should required 
Old User Name:_______________
Old Password:________________
New username:________________
New Password:________________

It needs more condition only like
 ".......
 WHERE username='"+txtOldUserName.Text+"' and password='"+txtOldPassword.Text+"'"; 

See the concept for what to do

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