C :: Linking Data Elements Within A Database
Nov 24, 2013
I am writing a contact book program in C that will run in the terminal. I am going to create a file to store the data separately, but have run into a few question areas:
1) It has occurred to me that it might be more efficient to setup the program so that it sorts the contact info by info type rather than by running through an index of the contacts and then linking all of that contact's information to that index. So basically one part of the file would be phone numbers, the other contact names, and so forth with each piece of data linked to another piece within the data file that corresponds to the same contact. Am I wrong to think this is a more efficient way to set up the file?
2)How would you link the data information to other pieces of data corresponding to the same contact in C? My thought is to do it with pointers, but I didn't know if it were possible to have the pointers as I didn't know if the pointer would point "persistently" to the data once the file closed.As I felt this is a more "in general" question, I have chosen to omit my code from this post (especially since there is not much "meat" in it to speak of).
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Apr 8, 2015
I had assign to do a project using c# window form.Now I am doing a smart part of coding which is let the data in textbox and using keypress function with a enter,the data will save in database and show on datagridview.I had searching how to do it online but all of them using mysql or sqlcommand something to do it! But my project is using the code that already done and can access without mysql or sql coding... Using this code to connect and show in datagridview...
using (TMPB_attn_DAL dalObj = new TMPB_attn_DAL())
{
dataGridView1.DataSource = dalObj.GetRecords().Cast<TMPB_attn>().ToList();
dataGridView1.Refresh();
}
This is the function code for me to add data inside database,it can run but just still cant save.
private void txt_proximity_KeyPress(object sender, KeyPressEventArgs e) {
if (e.KeyChar == (char)13) {
if (BusinessLogicLayer.TMS_GET_PROXIMITY_VALID_TO_USE(txt_proximity.Text) == true) {
TMPB_attn row_tmpb_attn = new TMPB_attn();
[code] ....
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Feb 22, 2015
I can not do transferring data to textboxes from database.
="c#">using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using MySql.Data.MySqlClient;
namespace WindowsFormsApplication1{
[code]....
I got the error this line:
read = cmd.ExecuteReader();
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Apr 26, 2015
In my WPF application i have a SQL class which i am trying to use to store all of my SQL queries so far this is working fine for when i want to return one piece of data like this:
public string GetEnquiry_ContactName(int EnquiryID) {
string ContactName = null;
//Try to do the following if not then show the error message.
try {
//Create the SQL Connection
SqlConnection cn = new SqlConnection(Models.M_GlobalVariables.GetConnection);
[Code] ....
But if i want to return a collection of data like this:
public ObservableCollection<CompanyNames> GetCompanyNames () {
public class CompanyNames {
public string CompanyName { get; set; }
public CompanyNames(string name) {
CompanyName = name;
[Code] ....
It does not work and i get 'Not all code paths return a value' and ''List_CompanyNames' is a 'property' but is used like a 'type''. But if i have it in my ViewModel like this:
//Code for the 'Company Names' dropdown box
public class CompanyNames {
public string CompanyName { get; set; }
public CompanyNames(string name) {
CompanyName = name;
[Code] ....
It works absolutely fine but the whole point of my SQL class is to have all my SQL code in that class instead of some of it in the ViewModel.
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Mar 17, 2014
I want to connect an access database (.mdb) to my Windows Forms application - this I can do and I have no problems viewing my table in server explorer.
Some code example or template that I can use as a base to learn from - I have literally trawled Google and Youtube and cannot find what I am after.
What I want to do is have a basic form, 2 text boxes and a button to save the data to my database.
FirstName and LastName are the 2 boxes.
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Mar 4, 2014
Background: I've created a projected and added a mdf database file to it.
I am attempting to fill my datagridview with data from a table that I've added to my mdf file.
I am having a hell of a time figuring out the correct connection string and datasource file path for it.
I've decided on using OleDB because that's what I am most familiar with.
I clearly see the rule "Don't tell us to give you code!" but I cannot find a good tutorial from START to FINISH on how to do what I am trying to do.
As stated, I think my connection string is wrong. Even if I change it to
OleDB (string conStr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=Database.mdf"
I get a new error saying it cannot recognize the database format.
public partial class DataViewer : Form {
string conStr = "Provider=SQLOLEDB;Data Source=Database.mdf";
DataSet dS = new DataSet();
DataSet tdS = new DataSet();
OleDbConnection con = null;
[Code] ....
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Apr 19, 2014
Exporting the data from the sql database to excel directly.this code is not working and i am not getting file in particular location. My connection string is :
Data Source=aswin-pcsqlexpress;Initial Catalog=pro;Integrated Security=True
using Excel=Microsoft.Office.Interop.Excel;
using System.Runtime.InteropServices;
namespace WindowsFormsApplication5 {
public partial class Form1 : Form {
SqlConnection con = new SqlConnection(ConfigurationSettings.AppSettings["SqlCon"].ToString());
[code]....
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Jan 17, 2013
i am student working on a project in c# to maintain the datas from a solar battery monitoring.i already imported the datas from the battery monnitoring and saved them in mysql database and retrived the data in c#.
i have problem in retriving the data in accordance with the date and time range selection.
what i am trying to do is there are more than 1000 datas in the table if i select two date and time the datas in the table should cross check these dates and show all the datas in the table in between those date&time
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Feb 12, 2014
using System;
using System.Collections.Generic;
using System.ComponentModel;
[Code]....
find the attachment.
Data is displaying in grid view but when i enter the particulars it's not inserting in to DB & grid view.
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Jan 5, 2013
I created a class (let call it X) which contains the structure to store the data from my data base. Them I have a class (call Y) which will contain a list for each row in my data base. Third, I have a class with thousands variables (Z). What I am trying to do is to take the list of objects (Y) that contains the data to initialize Z. What I want to now if I can do something like that.
Imaging that one of my rows contain the following data:
Type Nameofvariable etc...
"static const double; MNFAIL ; 0; 0; 0,25"
In my list I have a node with contain this data
I want to use the field Nameofvariable to initialize the variable called MNFAIL contained in my class Z.
Is it possible in C++
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Jul 6, 2012
I am busy with a project, it is going to consist out of 3 different windows which is logic enough for this whole code to be interactive.
It must be able to pull data into a windows form, displaying it into a textbox, and when you click on the textbox it needs to open up another window where you will have a windows form that will display data as the code loops through the questions in the database.
I am not sure how to push the data that has been selected on the database to the next window..
Here is my code for the first window:
;
namespace WindowsFormsApplication1
{
public partial class Form1 : Form {
//SqlConnection myConnection = new SqlConnection("Data Source=(local);Initial Catalog=KnowledgeEssentials;Integrated Security=SSPI");
//int intType = 0;
public Form1()
[code].....
With the second window the data in the table needs to be displayed and each row from the table needs to have a checkbox next to them, so that if the check box is checked, the relevant information of the checked row will show up in the 3rd window... so MY question is, HOW do I pull that data from that specific database and let it show in the listcheckbox?
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Dec 22, 2014
When server send data then client receive that data, in C# windows services where data receive continuously (Using IP Address and port number) . This below code writing in console application . i want implement same logic in windows service side. but i want data receive continuously.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
[Code]....
Above code write in console application, same logic implementing in windows service, but i want data receiving continuously
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Feb 20, 2014
I am trying to use smart pointers to sort and re-link potentially large data elements. I have defined a class in my code for smart pointers, as listed below:
template <typename T>
class sptr {
public:
sptr(T *_ptr=NULL) { ptr = _ptr; }
[Code] ....
The object I'm trying to sort is a singly-linked list containing class objects with personal records (i.e., names, phone numbers, etc.). The singly-linked list class has an iterator class within it, as listed below.
template <class T>
class slist {
private:
struct node {
node() { data=T(); next=NULL; }
[Code] .....
The following is my function within my list class for "sorting" using the smart pointers.
template <typename T>
void slist<T>::sort(){
vector< sptr<node> > Ap(N); // set up smart point array for list
//slist<T>::iterator iter = begin();
node *ptrtemp = head->next;
[Code] .....
I must have a bad smart pointer assignment somewhere because this code compiles, but when I run it, std::bad_alloc happens along with a core dump. Where am I leaking memory?
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Mar 1, 2013
private String[] GetExcelSheetNames(string excelFile) {
OleDbConnection objConn = null;
SqlConnection objSqlConn = null;
System.Data.DataTable dt = null;
try {
[code].....
Now I can fatch all the excel sheet belongs to the Excel File.But How can I check "If and Only If the sheets are havin Underscore in their name(eg. student_data,teachers_data) then only the data of the sheets will populate in tha data base"
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May 22, 2014
I am working on Explicit Linking of a DLL to an executable. But, when it comes to application, I have some troubles.
1) I try to export a class using C Language approach. (I would ask for other approaches later).
My dll project as follows:
dllmain.cpp
// dllmain.cpp : Defines the entry point for the DLL application.
#include "stdafx.h"
BOOL APIENTRY DllMain( HMODULE hModule,
DWORD ul_reason_for_call,
LPVOID lpReserved
[code]....
2) Related with the question above, what is the best way to provide a "pure" explicit linking? How can I explicitly link a dll without introducing the corresponding .lib and without including the dll's header file?
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Mar 8, 2013
i am trying to write program that prints out full lyrics to 99 bear song. Hoping for explanation or anything
The output would have to look like:
99 bottles of beer on the wall, 99 bottles of beer.
Take one down and pass it around, 98 bottles of beer on the wall.
My try below:
Code: #include <iostream>
using namespace std;
int main()
{
for(int i=99; i>=0 ;i--)
cout << i <<""<< " bottles of beer on the wall, "<<i<<" bottles of beer."<<endl;
for(int j=98; j>=0 ;j--){
cout <<endl;
cout << "Take one down and pass it around," <<j<<" bottles of beer on the wall."<<endl;
}
return 0;
}
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Oct 7, 2014
I am trying to refresh my memory here as I did some studies many years ago but the results elude me.Also todays c/c++ compilers may have better optimizations.Say I have a static library that includes three obj modules.Each of these object modules has a number of functions. These functions do not reference any other functions within the obj module.My main app links this library but only references one function from each of the object modules.
Question: Are the complete contents of each module linked into my main app or are todays linkers smart enough to just link the functions used?
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Feb 25, 2014
I am running a windows forms project. on the form there is a datagridview, a progress bar, a textbox and two 2 buttons.
The two buttons are used to navigate through the records(one for next record and the other for previous record) the textbox displays the record that is being currently viewed.
How can I link the progress with the database or in this case the datagridview and when the next button is pressed it increments and when the previous button is clicked it decrements and also the progress to be fully filled when the last record is reached ?
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Sep 7, 2012
I am forced to have the deceleration of a class template in the .h file.
See here: [URL] ....
This works perfectly fine, as long as i #inlcude the header file only in ONE .cpp file.
The moment i #inlude it in several .cpp files, i get LNK2005 already-defined errors.
a.obj : error LNK2005: "public: unsigned int * __thiscall theclass::themthod(void)" (?xxx@theclass@@QAEPAIXZ) already defined in b.obj
I would have assumed inclusion guards can protect me from this, but wrong.
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Jan 25, 2013
My Project is to Dynamically Link 2 Software for Co-simulation n C/C++. So that Output of One Software becomes Input of Other automatically . at present we input the parameters manually in both the software . what to do so that it pick up values itself and gives the output by solving each and everything at once in both the software .
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Jun 20, 2013
I have a libcx3d.a which contains my VrmlParser class and other classes which are used by VrmlParser. I have a main.cpp which does this :
VrmlParser vp = new VrmlParser();
double **VOB = vp.getVOB();
When I compile using g++ main.cpp -o main -L. -lcx3d, I get the following errors :
'VrmlParser' was not declared in this scope.
expected ';' before vp.
'vp' was not declared in this scope.
There is a header file called "VrmlParser.h" in the static library. Should I include this header file in main.cpp ? If so, will include "VrmlParser.h" work ? I have the .a and .cpp in the same directory. I can't find the header file for the static library.
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May 15, 2013
I find myself in a position where I am repeating the same pattern of, write shared lib, compile, link shared lib, write app lib "sandbox" dependent on shared lib, write shared lib, compile, link, write...
At each level of dependency I have to carry over previously shared libs, search directories, etc. How to automate this process, so I spend less time linking after each layer?
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Jul 16, 2014
I have built a static library that contains a macro. From a separate exe, I am calling this macro, but it doesn't work.
The compilation of the static library and that of the exe went okay.
Static lib contains just the macro definition.
Exe contains call to this macro.
Is there anything else that I need to do for this to work?
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Dec 17, 2014
I have written a program that uses boost in visual studio 2012. The only boost library I used is filesystem by doing.
1)Properties->Linker->General and adding the path or the .lib to the additional dependencies. The libraries, link at compile time.However when i move the exe to a different computer, it doesn't work. Therefore the libraries were dynamically not statically linked. So my question is how do I statically link the filesystem library, so that i can include boost/filesystem.hpp in visual studio 2012?
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Jul 30, 2014
I am having the issue of trying to call functions of a class through the header file.
Test.h
#ifndef TEST_H
#define TEST_H
class Test {
public:
void Hello();
[code]....
This code returns the error "undefined reference to 'Test::Hello()'"
All I am trying to do is call the Hello(); function in a seperate file.
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Sep 30, 2014
I have built Boost from the website using
./bootstrap.sh
./b2 install
I think all are installed properly. I am trying to use Xcode to include the library of boost:thread.My code links to the header file properly with " #include "boost/thread.hpp"" commented, as seen from the following:
However, it could not link properly to boost-thread if "#include "boost/thread.hpp"" is un-commented.
Error page is shown as:
I have linked the dynamic library libboost_thread.a and libboost_thread.dylib and included /usr/local/include into header search path and /usr/local/lib into library search path.
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