C# 连接数据库

private static void sqlcon(){
	SqlConnection con = new SqlConnection();
	con.ConnectionString = "server=.;database=database;uid=name;pwd=password";
	con.Open();//开启链接
	SqlCommand com = new SqlCommand();
	com.Connection = con;
	com.CommandType = CommandType.Text;
	string s = "select * from table_name";
	com.CommandText = s;
	SqlDataReader dr = com.ExecuteReader();//执行SQL语句
	if (dr.HasRows){//查到数据为true，反之为false
		if (dr.Read())
		{
			value = dr["letter"].ToString();
		}
		dr.Close();
	}
	Console.WriteLine(value);
	dr.Close();//关闭执行
	con.Close();//关闭数据库
}