C# 关于App.config问题

[zuisha8]

private void Form1_Load(object sender, EventArgs e)
{

ConnectionStringSettings settings = ConfigurationManager.ConnectionStrings["qq"];
conn = new SqlConnection(settings.ConnectionString);
da = new SqlDataAdapter("select 用户名称 from 用户表", conn);
DataSet ds = new DataSet();
if (conn.State == ConnectionState.Closed)
{
conn.Open();
}

da.Fill(ds, "用户表");
conn.Close();
cbxUserName.DataSource = ds.Tables["用户表"];
cbxUserName.DisplayMember = "用户名称";

}
总是提示实例失败

[mars199]

哦，不懂帮顶，期待高手

[bancxc]

AppSetting["qq"]???

[chaihf]

看你的 app.config 里面的
<configuration>
<connectionStrings>
。。。。
</connectionStrings>
</configuration>
是否正常。
不能实例化， 那应该是不正常，配置不对。

[wuyq11]

App.config怎么配置的
<connectionStrings>
<add name="PandaConnString"
connectionString=""
providerName="" />
</connectionStrings>

string cnString = ConfigurationManager.ConnectionStrings["PandaConnString"].ConnectionString;

[chaihf]

一般用 AppSetting 的简单，通用。

[娃ha哈]

            SqlConnection con = new SqlConnection();
            con.ConnectionString = ConfigurationManager.ConnectionStrings["qq"].ToString(); 
            con.Open();
            string str = "select * from tablename";             

Lz 试试看

[changjiangzhibin]

//试试，另在Conn=行设断点，看连接字串有没有问题
private void Form1_Load(object sender, EventArgs e)
  {    
  ConnectionStringSettings settings = ConfigurationManager.ConnectionStrings["qq"];
  conn = new SqlConnection(settings.ConnectionString);
  da = new SqlDataAdapter("select 用户名称 from 用户表", conn);
  DataTable dt = new DataTable();    
  da.Fill(dt);
  cbxUserName.DataSource = dt;
  cbxUserName.DisplayMember = "用户名称";
  }

[smallMage]

跟踪调试，看在哪一步出错了

[无涯大者]

楼主的App.config怎么配置的

<connectionStrings>  
  <add name="createConn"  connectionString=""  providerName="" />  
</connectionStrings>  
或者
 <appSettings>
        <add key="createConn" value=" "/>
    </appSettings>
string cnString = ConfigurationManager.ConnectionStrings["createConn"].ConnectionString;  

[likedefly]

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<connectionStrings>
<add name="qq" connectionString="server=192.168.100.58\FLY;database=CSMAR_Log;uid=sa;password=sa;" providerName="System.Data.SqlClient" />
</connectionStrings>
</configuration>

[wjhx]

楼上这些足可解决了

[zhenshangzhengren]

在书上好像是这样的string str=ConfigurationManager.ConnectionStrings[""].ConnectionString;
SqlConnection con=SqlConnection(string);

[xiaotiange]

ConnectionStringSettings settings = ConfigurationManager.ConnectionStrings["qq"];
conn = new SqlConnection(settings.ConnectionString);

你这样写不对哦

[zuisha8]

app.config里这么写的：
<connectionStrings>
<add name ="qq" connectionString="server=(local\\sqlexpress;database=studentDB;integrated security=true"/>

</connectionStrings>
ConnectionStringSettings settings = ConfigurationManager.ConnectionStrings["qq"];
conn = new SqlConnection(settings.ConnectionString);

你这样写不对哦 这样不对应该怎么写呢？

[好吃的松子]

实例失败是什么意思，有异常吗？还是编译错误？

[haoll714773361]

顶4楼 4楼的正确

[harker007]

[Quote=引用 8 楼 zuisha8 的回复:]

connectionString="server=.\SQLEXPRESS;database=studentDB;integrated security=true;User Id=sa;Password=123456"

ConnectionStringSettings settings = ConfigurationManager.ConnectionStrings["qq"].Tostring();
SqlConnection conn = new SqlConnection(settings);