1、服务端对前端传过来的参数值进行类型验证；

2、服务端执行sql，使用参数化传值，而不要使用sql字符串拼接；

3、服务端对前端传过来的数据进行sql关键词过来与检测；

4、在UI录入时，要控制数据的类型和长度、防止SQL注入式攻击，系统提供检测注入式攻击的函数，一旦检测出注入式攻击，该数据即不能提交；

5、业务逻辑层控制，通过在方法内部将SQL关键字用一定的方法屏蔽掉，然后检查数据长度，保证提交SQL时，不会有SQL数据库注入式攻击代码；但是这样处理后，要求UI输出时将屏蔽的字符还原。因此系统提供屏蔽字符 的函数和还原字符的函数。

6、在数据访问层，绝大多数采用存储过程访问数据，调用时以存储过程参数的方式访问，也会很好的防止注入式攻击。

public class SqlInjectHelper:System.Web.UI.Page
{
	private static string StrKeyWord = "select|insert|delete|from|count(|drop table|update|truncate|
asc(|mid(|char(|xp_cmdshell|exec|master|net local group administrators|net user|or|and";
	private static string StrSymbol = ";|(|)|[|]|{|}|%|@|*|‘|!";
	private HttpRequest request;
	
	public SqlInjectHelper(System.Web.HttpRequest _request)
	{
		this.request = _request;
	}
	
	public bool CheckSqlInject()
	{
		return CheckRequestQuery() || CheckRequestForm();
	}
	
	///<summary> ///检查URL中是否包含Sql注入 
	/// <param name="_request">当前HttpRequest对象</param> 
	/// <returns>如果包含sql注入关键字，返回：true;否则返回：false</returns> 
	///</summary> 
	public bool CheckRequestQuery()
	{
		if (request.QueryString.Count > 0)
		{
			foreach (string sqlParam in this.request.QueryString)
			{
				if (sqlParam == "__VIEWSTATE") 
					continue;
				if (sqlParam == "__EVENTVALIDATION") 
					continue;
				if (CheckKeyWord(request.QueryString[sqlParam].ToLower()))
				{
					return true;
				}
			}
		}
		return false;
	}

	///<summary> 
	///检查提交的表单中是否包含Sql注入关键字
	/// <param name="_request">当前HttpRequest对象</param> 
	/// <returns>如果包含sql注入关键字，返回：true;否则返回：false</returns> 
	///</summary> 
	public bool CheckRequestForm()
	{
		if (request.Form.Count > 0)
		{
			foreach (string sqlParam in this.request.Form)
			{
				if (sqlParam == "__VIEWSTATE") 
					continue;
				if (sqlParam == "__EVENTVALIDATION") 
					continue;
				if (CheckKeyWord(request.Form[sqlParam]))
				{
					return true;
				}
			}
		}
	return false;
	}

///<summary> 
///检查字符串中是否包含Sql注入关键字 
/// <param name="_key">被检查的字符串</param> 
/// <returns>如果包含sql注入关键字，返回：true;否则返回：false</returns> 
///</summary> 
	private static bool CheckKeyWord(string _key)
	{
		string[] pattenKeyWord = StrKeyWord.Split(‘|‘);
		string[] pattenSymbol = StrSymbol.Split(‘|‘);
		foreach (string sqlParam in pattenKeyWord)
		{
			if (_key.Contains(sqlParam + " ") || _key.Contains(" " + sqlParam))
			{
				return true;
			}
		}
		foreach (string sqlParam in pattenSymbol)
		{
			if (_key.Contains(sqlParam))
			{
				return true;
			}
		}
		return false;
	}
}

protected void Application_BeginRequest(object sender, EventArgs e)
{
	SqlInjectHelper myCheck = new SqlInjectHelper(Request);
	bool result = myCheck.CheckSqlInject();
	if (result)
	{
		Response.ContentType = "text/plain";
		Response.Write("您提交的数据有恶意字符！");
		Response.End();
	}
}

public class Handler1 : IHttpHandler
{
	public void ProcessRequest(HttpContext context)
	{
		SqlInjectHelper myCheck = new SqlInjectHelper(context.Request);
		bool result = myCheck.CheckSqlInject();
		context.Response.ContentType = "text/plain";
		context.Response.Write(result?"您提交的数据有恶意字符！":"");
		context.Response.StatusCode = result ? 500 : 200;
	}
	public bool IsReusable
	{
		get
		{
			return false;
		}
	}
}

public class SafeHelper
{
	private const string StrRegex = @"<[^>]+?style=[\w]+?:expression\(|\b(alert|confirm|prompt)\b
|^\+/v(8|9)|<[^>]*?=[^>]*?&#[^>]*?>|\b(and|or)\b.{1,6}?(=|>|<|\bin\b|\blike\b)|/\*.+?\*/|<\s*script\b|
<\s*img\b|\bEXEC\b|UNION.+?SELECT|UPDATE.+?SET|INSERT\s+INTO.+?VALUES|(SELECT|DELETE).+?FROM|
(CREATE|ALTER|DROP|TRUNCATE)\s+(TABLE|DATABASE)";

	public static bool PostData()
	{
		bool result = false;
		for (int i = 0; i < HttpContext.Current.Request.Form.Count; i++)
		{
			result = CheckData(HttpContext.Current.Request.Form[i].ToString());
			if (result)
			{
				break;
			}
		}
		return result;
	}

	public static bool GetData()
	{
		bool result = false;
		for (int i = 0; i < HttpContext.Current.Request.QueryString.Count; i++)
		{
			result = CheckData(HttpContext.Current.Request.QueryString[i].ToString());
			if (result)
			{
				break;
			}
		}
		return result;
	}

	public static bool CookieData()
	{
		bool result = false;
		for (int i = 0; i < HttpContext.Current.Request.Cookies.Count; i++)
		{
			result = CheckData(HttpContext.Current.Request.Cookies[i].Value.ToLower());
			if (result)
			{
				break;
			}
		}
		return result;
	}

	public static bool referer()
	{
		bool result = false;
		return result = CheckData(HttpContext.Current.Request.UrlReferrer.ToString());
	}

	public static bool CheckData(string inputData)
	{
		if (Regex.IsMatch(inputData, StrRegex))
		{
			return true;
		}
		else
		{
			return false;
		}
	}
}

var Shipcity;
ShipCity = Request.form ("ShipCity");
var sql = "select * from OrdersTable where ShipCity = '" + ShipCity + "'";

SELECT * FROM OrdersTable WHERE ShipCity = 'Guangdong'

SELECT * FROM OrdersTable WHERE ShipCity = 'Guangdong';drop table OrdersTable–'

SqlDataAdapter myCommand = new SqlDataAdapter("AuthorLogin", conn); 
myCommand.SelectCommand.CommandType = CommandType.StoredProcedure; 
SqlParameter parm = myCommand.SelectCommand.Parameters.Add("@au_id", SqlDbType.VarChar, 11); 
parm.Value = Login.Text;

SqlDataAdapter myCommand = new SqlDataAdapter( "SELECT au_lname, au_fname FROM Authors WHERE au_id = @au_id", conn); 
SQLParameter parm = myCommand.SelectCommand.Parameters.Add("@au_id", SqlDbType.VarChar, 11); 
Parm.Value = Login.Text;

private string SafeSqlLiteral(string inputSQL) 
{ 
	return inputSQL.Replace("'", "''"); 
}

s = s.Replace("[", "[[]"); 
s = s.Replace("%", "[%]"); 
s = s.Replace("_", "[_]");