[英]Error with SQL Server connection string
I've tried a million different methods of achieving this yet found none that work. 我已经尝试了100万种不同的方法来实现这一目标,但没有一个可行的方法。 Scroll down to bottom.
向下滚动到底部。 ( Note, this is a login form using a SQL Server database )
( 请注意,这是使用SQL Server数据库的登录表单 )
DatabaseConnection.cs: DatabaseConnection.cs:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
namespace AllIn1Database
{
class DatabaseConnection
{
private string sql_string;
private string strCon;
System.Data.SqlClient.SqlDataAdapter da_1;
public string Sql
{
set
{
sql_string = value;
}
}
public string connection_string
{
set { strCon = value; }
}
public System.Data.DataSet GetConnection
{
get { return MyDataSet(); }
}
private System.Data.DataSet MyDataSet()
{
System.Data.SqlClient.SqlConnection con = new System.Data.SqlClient.SqlConnection(strCon);
con.Open();
da_1 = new System.Data.SqlClient.SqlDataAdapter(sql_string, con);
System.Data.DataSet dat_set = new System.Data.DataSet();
da_1.Fill(dat_set, "Table_Data_1");
con.Close();
return dat_set;
}
}
}
Form1.cs: Form1.cs中:
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.Sql;
using System.Data.SqlClient;
using System.Data.SqlTypes;
namespace AllIn1Database
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
DatabaseConnection objConnect;
string conString;
DataSet ds;
SqlConnection con = new SqlConnection();
private void tnLogin_Click(object sender, EventArgs e)
{
try{
System.Data.SqlClient.SqlConnection con = new System.Data.SqlClient.SqlConnection();
con.Open();
String cmp = "SELECT ISNULL(stUsername, '') AS stUsername, ISNULL(stPassword,'') AS stPassword, ISNULL(stRole,'') AS stRole FROM LoginDetails WHERE stUsername='" + txtUname.Text + "' and stPassword='" + txtPass.Text + "'";
SqlCommand cmd = new SqlCommand(cmp, con);
SqlDataAdapter da = new SqlDataAdapter(cmd);
SqlDataReader dr = cmd.ExecuteReader();
while (dr.Read())
{
string userText = txtUname.Text;
string passText = txtPass.Text;
if (this.CompareStrings(dr["Name"].ToString(), userText) &&
this.CompareStrings(dr["Password"].ToString(), passText)){
MessageBox.Show("Logged on as" + txtUname.Text);
}
else
{
MessageBox.Show("Invalid Logon Details.");
}
dr.Close();
con.Close();
}
}
catch (Exception err) {
MessageBox.Show(err.Message);
}
}
private void Form1_Load(object sender, EventArgs e)
{
try
{
objConnect = new DatabaseConnection();
conString = Properties.Settings.Default.DatabaseConnectionString;
objConnect.connection_string = conString;
objConnect.Sql = Properties.Settings.Default.SQL;
ds = objConnect.GetConnection;
}
catch (Exception err)
{
MessageBox.Show(err.Message);
}
}
private bool CompareStrings(string string1, string string2)
{
return String.Compare(string1, string2, true, System.Globalization.CultureInfo.InvariantCulture) == 0 ? true : false;
}
}
}
The error occurs in the line 该行中发生错误
System.Data.SqlClient.SqlConnection con = new System.Data.SqlClient.SqlConnection(strCon);
The error says 错误说
strCon does not exist in this context.
在这种情况下,strCon不存在。
How would I make this successfully connect without throwing this error? 我如何使它成功连接而不抛出此错误?
You're instantiating a connection without a connectionstring. 您正在实例化没有连接字符串的连接。 And I do not see you setting it after the line:
我看不到您在下一行之后进行设置:
System.Data.SqlClient.SqlConnection con = new System.Data.SqlClient.SqlConnection();
Assuming your connection string is in Properties.Settings.Default.DatabaseConnectionString, you would do something like: 假设您的连接字符串位于Properties.Settings.Default.DatabaseConnectionString中,您将执行以下操作:
System.Data.SqlClient.SqlConnection con = new System.Data.SqlClient.SqlConnection(Properties.Settings.Default.DatabaseConnectionString);
You don't have a connection string / havn't given strCon a value, you would need to do something like: 您没有连接字符串/没有为strCon赋值,您需要执行以下操作:
strCon = "myConnectionString";
to find out what the connection string is for you can use this website: 要查找连接字符串的含义,可以使用以下网站:
http://www.connectionstrings.com/ http://www.connectionstrings.com/
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.