ADO.NET（一）数据库连接串的几种写法

    class Program
    {
        static void Main(string[] args)
        {
            SqlConnection conn = new SqlConnection();

            //1.手写
            //string connStr = "server=.;database=db1;uid=sa;pwd=123";

            //2.SqlConnectionStringBuilder生成连接字符串
            //SqlConnectionStringBuilder connStrBuilder = new SqlConnectionStringBuilder();
            //connStrBuilder.DataSource = ".";//设置数据源
            //connStrBuilder.InitialCatalog = "db1";//数据库名
            //connStrBuilder.UserID = "sa";//账号
            //connStrBuilder.Password = "123";//密码
            //connStrBuilder.Pooling = false;//禁用连接池
            //string connStr = connStrBuilder.ConnectionString;

            //3.读取配置文件里的连接字符串
            //3.1
            //string connStr = ConfigurationManager.ConnectionStrings["connStr"].ConnectionString;//读取连接字符串
            //3.2
            string connStr = ConfigurationManager.AppSettings["connStr"].ToString();


            //连接字符串如果任何一个元素设置不正确，都不能正常打开conn
            conn.ConnectionString = connStr;
            conn.Open();
            conn.Close();
        }
    }