如何检查c＃中sql中是否存在用户名和密码

问题描述：

Hai，

我在c＃web application中有用户名文本框和密码trxt框。我有一个sql表登录其中包含用户名和密码。如何验证SQL表中是否存在用户名或密码。

提前致谢

Hai,

I am having username textbox and password trxt box in c# web application.I am having a sql table "Login" which contains username and password.How to validate whether username or password exists in SQL table.

Thanks in advance

答

首先看一下：密码存储：怎么做它。 [ ^ ] - 它不包括存储或检索来自teh dtabase的数据，但这是微不足道的：

Start by looking at this: Password Storage: How to do it.[^] - it doesn't cover storing or retrieving the data from teh dtabase, but that is the trivial bit:

using (SqlConnection con = new SqlConnection(strConnect))
    {
    con.Open();
    using (SqlCommand cmd = new SqlCommand("SELECT password FROM myTable WHERE username=@UN", con))
        {
        cmd.Parameters.AddWithValue("@UN", txtUserName.Text);
        using (SqlDataReader reader = cmd.ExecuteReader())
            {
            if (reader.Read())
                {
                byte[] psw = (byte[])reader["password"];
                ...Check as in the Tip
                }
            }
        }
    }

你也可以查看这个（当然除了格里夫已经给出的答案）

check-if-username-已经存在于数据库中 [ ^ ]

You can check this also(off course apart from the answer Griff already gave)

checking-if-username-already-exists-within-the-databasae[^]

如何进行查询？你可以结合WHERE做一个SELECT，看看它返回什么，如果有数据，两者都存在，如果没有......它们不在表中

http://www.w3schools.com/sql/sql_where.asp [ ^ ]

How about doing a query? You can do a SELECT combined with WHERE and see what it returns, if there is data, both exists, if not... they are not in the table

http://www.w3schools.com/sql/sql_where.asp[^]

如何检查c＃中sql中是否存在用户名和密码

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