帮忙看看连数据库时候为啥出System.InvalidOperationException

Question

app.config<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <connectionStrings>
    <add name="connStr" providerName="System.Data.SqlClient"
         connectionString="SERVER=.\\SQLEXPRESS;DATABASE=wfcp;UID=sa;PWD=123;"/>
  </connectionStrings>
</configuration>
SqlHelperusing System;
using System.Collections.Generic;
using System.Text;
using System.Data.SqlClient;
using System.Configuration;
using System.Data.Common;namespace WinFormCourseProject
{
    class SqlHelper
    {
        public static DbConnection GetDataBaseConnection(string name)
        {
            string connString = ConfigurationManager.ConnectionStrings[name].ConnectionString;
            SqlConnection cn = new SqlConnection();
            cn.ConnectionString = connString;            return cn;
        }
    }
}
主程序里
SqlConnection cn = (SqlConnection)SqlHelper.GetDataBaseConnection("connStr");
SqlCommand cmd = cn.CreateCommand();
cmd.CommandText = sqlStr;然后是open什么的

Answer 1

SQL Server connection strings
SQL ODBC connection strings
Standard Security:< br> "Driver={SQLServer};Server=Your_Server_Name;Database=Your_Database_Name;Uid=Your_Username;Pwd=Your_Password;"Trusted connection:< br> "Driver={SQLServer};Server=Your_Server_Name;Database=Your_Database_Name;Trusted_Connection=yes;"
SQL OLE DB connection strings
Standard Security:
"Provider=SQLOLEDB;Data Source=Your_Server_Name;Initial Catalog= Your_Database_Name;UserId=Your_Username;Password=Your_Password;"Trusted connection:
"Provider=SQLOLEDB;Data Source=Your_Server_Name;Initial Catalog=Your_Database_Name;Integrated Security=SSPI;"
SQL OleDbConnection .NET strings
Standard Security:
"Provider=SQLOLEDB;Data Source=Your_Server_Name;Initial Catalog= Your_Database_Name;UserId=Your_Username;Password=Your_Password;"Trusted connection:
"Provider=SQLOLEDB;Data Source=Your_Server_Name;Initial Catalog=Your_Database_Name;Integrated Security=SSPI;"
SQL SqlConnection .NET strings
Standard Security:
1. "Data Source=Your_Server_Name;Initial Catalog= Your_Database_Name;UserId=Your_Username;Password=Your_Password;" < br>2. "Server=Your_Server_Name;Database=Your_Database_Name;UserID=Your_Username;Password=Your_Password;Trusted_Connection=False"Trusted connection:
1. "Data Source=Your_Server_Name;Initial Catalog=Your_Database_Name;Integrated Security=SSPI;"
2."Server=Your_Server_Name;Database=Your_Database_Name;Trusted_Connection=True;" 

Answer 2

   <center><h1>SQL Server connection strings</h1></center>
   
   <h2>SQL ODBC connection strings</h2>
   <b>Standard Security:</b><
   br> 
   "Driver={SQLServer};Server=Your_Server_Name;Database=Your_Database_Name;Uid=Your_Username;Pwd=Your_Password;"
   <br>
   <br>
   <b>Trusted connection:</b><
   br> "Driver={SQLServer};Server=Your_Server_Name;Database=Your_Database_Name;Trusted_Connection=yes;" 
   
   <h2>SQL OLE DB connection strings</h2>   <b>Standard Security:</b><br>
   "Provider=SQLOLEDB;Data Source=Your_Server_Name;Initial Catalog= Your_Database_Name;UserId=Your_Username;Password=Your_Password;"
   <br>
   <br>
   <b>Trusted connection:</b><br>
   "Provider=SQLOLEDB;Data Source=Your_Server_Name;Initial Catalog=Your_Database_Name;Integrated Security=SSPI;"
   
   <h2>SQL OleDbConnection .NET strings</h2>
   <b>Standard Security:</b><br>   "Provider=SQLOLEDB;Data Source=Your_Server_Name;Initial Catalog= Your_Database_Name;UserId=Your_Username;Password=Your_Password;"
   <br>
   <br>
   <b>Trusted connection:</b><br>
   "Provider=SQLOLEDB;Data Source=Your_Server_Name;Initial Catalog=Your_Database_Name;Integrated Security=SSPI;"
   
   <h2>SQL SqlConnection .NET strings</h2>
   <b>Standard Security:</b><br>
   1. "Data Source=Your_Server_Name;Initial Catalog= Your_Database_Name;UserId=Your_Username;Password=Your_Password;" 
   <
    br>2. "Server=Your_Server_Name;Database=Your_Database_Name;UserID=Your_Username;Password=Your_Password;Trusted_Connection=False" 
   <br>   <br>
   <b>Trusted connection:</b><br>
   1. "Data Source=Your_Server_Name;Initial Catalog=Your_Database_Name;Integrated Security=SSPI;" 
   <br>
    2."Server=Your_Server_Name;Database=Your_Database_Name;Trusted_Connection=True;" 
   
   <br>
   <br>
   <center>
    <hr>    <A href="index.htm">SQL Strings Home</a> | 
    <A href="SQL-Server-connection-strings.htm">SQL Server connection strings</a> | 
    <A href="MS-Access-connection-strings.htm">MS Access connection strings</a> |
    <A href="MySQL-connection-strings.htm">MySQL connection strings</a> |
    <A href="Oracle-connection-strings.htm">Oracle connection strings</a> |
    <A href="Database-Glossary.htm">Database Glossary</a>   </center>

Answer 3

http://www.sqlstrings.com/SQL-Server-connection-strings.htm
没办法，不会发帖子，怎么弄都不好看。