C# WinForm连接SQL Server数据库的不同方式

      一、不同字符串定义方式
      1）直接定义字符串并连接
      `static SqlConnection conn;//定义连接对象
      public static SqlConnection Connection//连接对象的属性
    {
        get
        {
            if (conn == null)
            {
                string connstr = "Data Source = (local); uid=sa;pwd=12345678;Initial Catalog =data_db; Integrated Security=SSPI";//本地连接  
                conn = new SqlConnection(connstr);
                conn.Open();
            }
            else if (conn.State == ConnectionState.Closed)
            {
                conn.Open();
            }
            else if (conn.State == ConnectionState.Broken)
            {
                conn.Close();
                conn.Open();
            }
            return conn;
        }
    }`

2）字符串保存在app.config文件中定义
app.config文件中添加：



数据库连接类中引用：
public static string connstr = ConfigurationManager.ConnectionStrings["ConStr"].ConnectionString; static SqlConnection conn; public static SqlConnection Connection//连接对象的属性 { get { if (conn == null) { string connstr = ConfigurationManager.ConnectionStrings["ConStr"].ConnectionString; conn = new SqlConnection(connstr); conn.Open(); } else if (conn.State == ConnectionState.Closed) { conn.Open(); } else if (conn.State == ConnectionState.Broken) { conn.Close(); conn.Open(); } return conn; }
二、连接字符串各种情况下的定义
1）SQL身份验证方式的本地数据库连接
string strSqlConnect = “Data Source = (local); uid=sa;pwd=12345678;Initial Catalog =data_db; Integrated Security=SSPI”;
2）Windows身份验证方式的本地数据库连接
string strSqlConnect = “Data Source = (local); Initial Catalog =data_db; Integrated Security=SSPI”;
3）SQL身份验证方式的远程数据库连接
string strSqlConnect = string.Format(@“server={0};uid=sa;pwd=12345678;database=data_db;Trusted_Connection=no”, ip + “,1433”);//使用IP远程登录
其中：ip为服务器IP地址，要确保你所使用的端口号在远程服务器上已经开放。