c# string strsql = "select sh,yf from shyf where gk="+this.textBox1.Text ,where 后面两个条件怎么写

c# string strsql = select sh,yf from shyf where gk=+this.textBox1.Text ,where 后面两个条件怎么写 String strSQL = SELECT * FROM Login +WHERE XM= ' + Login + '; 如何运用String.Substring(string.length-1)C#的! 在C#中这是this.txtType.Text = string.Empty什么意思? String.Format 在C#中的意思 string strsql = select * from tb_users where Role='+loginrole+'and;为什么要加那么多引号,其中的双引号和单引号起什么作用,还有为什么要用+号,and是干什么用的, C#里面的string和String有什么区别?string a = gaga;String b=gaga;if (a == b)Console.Write(ok);elseConsole.Write(no);System.Threading.Thread.Sleep(1000);结果输出为ok,两个完全一样 c# public static bool IsSelectNode(string xmlPath,string node){XmlDocument xmlDoc = new XmlDocument();xmlDoc.Load(xmlPath);XmlNode result = xmlDoc.SelectSingleNode(@// + node);return result = null;//就这行} C#中label.Text += String.Format(,)是怎么使用的,作用是什么?this.lab_ID.Text += String.Format( {0},Config.Instance.AMData.ID);中+=是什么作用? C#中怎么测试变量类型?如:int num = 434;怎么知道他是int?string temp = gfdg;怎么知道他是string? C#枚举的转换问题class Program { enum Gender { 男, 女 } static void Main(string[] args) { Console.WriteLine(Input); string s =Console.ReadLine(); c#中 s += (string.Format({0}*{1}={2},i,j,i * j)).PadRight(8);这是什么意思 c#中 s += (string.Format({0}*{1}={2},i,j,i * j)).PadRight(8);这是什么意思 C#语法的问题 get set的用法public class Users { private int _userid; private string _username; private string _userpwd; public int UserId { get { return this._userid; } set { this._userid = value; } } public string UserName { get { return this 关于C#中get:和set;用法在类中定义属性public string name{get;set;}和private string name;public string Name{get { return name; }set { name= value; }}有什么区别.感觉都是封装字段. C#语法问题 this的用法public class Users{private int _userid;private string _username;private string _userpwd;public int UserId{get { return this._userid; }set { this._userid = value; }}public string UserName{get { return this._username; }set { String was not recognized as a valid DateTime.c#中 用户定义类型未定义的错误Public Function Execute SQL(ByVal strSQL As String) As ADODB.Recordset应该怎么改呢?