一般來說,在更新DataTable或是DataSet時,如果不採用SqlParameter,那麼當輸入的Sql語句出現歧義時,如字符串中含有單引號,程序就會發生錯誤,並且他人可以輕易地通過拼接Sql語句來進行注入攻擊。
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string
sql = "update Table1 set name = 'Pudding' where ID = '1'" ; //未採用SqlParameter SqlConnection conn =
new SqlConnection(); conn.ConnectionString =
"Data Source=.\\SQLExpress;Integrated Security=true;AttachDbFilename=|DataDirectory|\\Database.mdf;User Instance=true" ; //連接字符串與數據庫有關 SqlCommand cmd =
new SqlCommand(sql, conn); try { conn.Open(); return (cmd.ExecuteNonQuery()); } catch
(Exception) { return
-1; throw ; } finally { conn.Close(); } |
一、Add方法
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SqlParameter sp =
new SqlParameter( "@name" ,
"Pudding" ); cmd.Parameters.Add(sp); sp = new
SqlParameter( "@ID" ,
"1" ); cmd.Parameters.Add(sp); |
該方法每次只能添加一個SqlParameter。上述代碼的功能是將ID值等於1的字段name更新爲Pudding(人名)。
二、AddRange方法
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SqlParameter[] paras =
new SqlParameter[] {
new SqlParameter( "@name" ,
"Pudding" ),
new SqlParameter( "@ID" ,
"1" ) }; cmd.Parameters.AddRange(paras); |
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public
int SavePhoto( string
photourl) { FileStream fs =
new FileStream(photourl, FileMode.Open, FileAccess.Read); //創建FileStream對象,用於向BinaryReader寫入字節數據流 BinaryReader br =
new BinaryReader(fs); //創建BinaryReader對象,用於寫入下面的byte數組 byte [] photo = br.ReadBytes(( int )fs.Length);
//新建byte數組,寫入br中的數據 br.Close(); //記得要關閉br fs.Close(); //還有fs string
sql = "update Table1 set photo = @photo where ID = '0'" ; SqlConnection conn =
new SqlConnection(); conn.ConnectionString =
"Data Source=.\\SQLExpress;Integrated Security=true;AttachDbFilename=|DataDirectory|\\Database.mdf;User Instance=true" ; SqlCommand cmd =
new SqlCommand(sql, conn); SqlParameter sp =
new SqlParameter( "@photo" , photo); cmd.Parameters.Add(sp); try { conn.Open(); return
(cmd.ExecuteNonQuery()); } catch
(Exception) { return
-1; throw ; } finally { conn.Close(); } } public
void ReadPhoto( string
url) { string
sql = "select photo from Table1 where ID = '0'" ; SqlConnection conn =
new SqlConnection(); conn.ConnectionString =
"Data Source=.\\SQLExpress;Integrated Security=true;AttachDbFilename=|DataDirectory|\\Database.mdf;User Instance=true" ; SqlCommand cmd =
new SqlCommand(sql, conn); try { conn.Open(); SqlDataReader reader = cmd.ExecuteReader(); //採用SqlDataReader的方法來讀取數據 if
(reader.Read()) { byte [] photo = reader[0]
as byte []; //將第0列的數據寫入byte數組 FileStream fs =
new FileStream(url,FileMode.CreateNew);創建FileStream對象,用於寫入字節數據流 fs.Write(photo,0,photo.Length); //將byte數組中的數據寫入fs fs.Close(); //關閉fs } reader.Close(); //關閉reader } catch
(Exception ex) { throw ; } finally { conn.Close(); } } } |