如何在csharp c#中使用小写字母控制登录表单 [英] how to control a login form with lowercase in csharp c#

问题描述

SqlDataAdapter da = new SqlDataAdapter("select * from users where username=''" + txtUser.Text + "''and password=''" + txtPsswrd.Text + "'' ", con);
            DataSet ds = new DataSet();
            da.Fill(ds, "users");
            DataView dv = new DataView(ds.Tables["users"]);

            if (dv.Count == 0)
            {
                MessageBox.Show("wrong username or password");
                txtUser.Focus();
                txtUser.Text = "";
                txtPsswrd.Text = "";
            }
            else
            {
                MDI dm = new MDI();
                dm.Show();
                this.Hide();
            }
        }

推荐答案

尽管您已经给出了答案，但我想强调的是，您永远不要在SQL查询中使用串联值.这使您容易遇到各种问题，例如:
-SQL注入
-数据类型不匹配等.

因此，不要串联值，而使用 SqlParameter [ ^ ].

因此，您的查询应类似于:

Although you have already given an answer, I want to emphasize that you should never ever use concatenated values inside a SQL query. This leaves you open to different kinds of problems like:
- SQL injection
- data type mismatches and so on.

So instead of concatenating the values, use SqlParameter[^].

So your query should look something like:

SqlDataAdapter da = new SqlDataAdapter("select * from users where username=@username and password=@password", con);
...

区分大小写的搜索查询在这里使用非常简单.

case sensitive search query will very simple to use here..

"select * from users where username COLLATE Latin1_General_CS_AS =''" + txtUser.Text + "''and password COLLATE Latin1_General_CS_AS =''" + txtPsswrd.Text + "'' "

这将执行区分大小写的搜索...并且如果输入的数据大小写与存储的大小写不同，则不会返回任何值...

this will do case sensitive search... and if entered data case is different from that of stored, doesn''t return any value...

在数据库中，如果您存储了用户名和小写的密码，然后最好将所有文本框输入转换为小写.

In your database , if you stored username and password in lowercase, then Better convert all the textbox input to lower.

SqlDataAdapter da = new SqlDataAdapter("select * from users where username='" + txtUser.Text.ToString().ToLower() + "'and password='" + txtPsswrd.TextToString().ToLower() + "' ", con);

或尝试这个

or try this

.lowercase {text-transform: lowercase}

这将使在文本框中输入的数据变为小写.
您必须将cssclass小写分配给文本框.但这不允许您在文本框中添加数字和符号

This will make the data entered in the text box as lowercase.
u have to assign the cssclass lowercase to the textbox. but this wont allow you to add numbers and symbols in textbox

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