Using variable from c++ code in sql

Question

I am working now with sqlite3. I want to use variable barcode_prog in SELECT. I have file of database sql_db with table PT and columns BarCode and Name. But I want to use anyone string in SELECT, which will set in programm. I ask my question in comment in code. Help, please :)

#include "stdafx.h"
#include "sqlite3.h"
#include <iostream>

int data (void *unused, int field_num, char **value, char **field_name)
{
    for (int i = 0; i < field_num; i++)
    {
        std::cout << value[i] << " = " << field_name[i] << std::endl;
    }
    return 0;
}

int main()
{
    int error;
    char *barcode_prog = "4813538002837";
    char *errmsg;
    sqlite3 *db;
    char *sql = "SELECT * FROM PT WHERE ?"; // here i want to use barcode_prog like     "SELECT * FROM PT WHERE BarCode = barcode_prog"
    error = sqlite3_open("sql_db", &db);
    if (error != SQLITE_OK) 
    {
        std::cout << "Cannot read database" << sqlite3_errmsg(db) << std::endl;
    }

    error = sqlite3_exec(db, sql, data, 0, &errmsg);

    if (error != SQLITE_OK) 
    {
        std::cout << "ERROR!" << errmsg << std::endl;
        sqlite3_free(errmsg);
    }

    system ("pause");
    sqlite3_close(db);
    return 0;
}

john.pavan · Accepted Answer · 2013-03-16 12:22:10Z

1

Probably a few ways to do this. I think the simplest is to use std::stringstream.

// your code
std::stringstream stream;
stream << "SELECT * FROM PT WHERE BarCode = " << barcode_prog.
// ...
error = sqlite3_exec(db, stream.str().c_str(), data, 0, &errmsg);
//...

answered Mar 16, 2013 at 12:22

john.pavan

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1 Comment

Artyom Rusak Over a year ago

Hello again. Can you write one more way, please!

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