I have a problem with an INSERT INTO command using SQLite3 in C++.
I want to save different strings in an existing database.
I already tested it with static values. There it works fine.
But when I want to save generated strings in that database, the database is empty every time.
Thats my c++ code:
#include <stdio.h>
#include <stdlib.h>
#include <sqlite3.h>
#include <string>
#include <sstream>
#include "createdb.h"
using namespace std;
/* Converts Strings into quotes */
string quotesql( const string& s ) {
return string("'") + s + string("'");
}
double addquery(string name, string email, double temp, double humidy, double intervall)
{
sqlite3 *db;
char *zErrMsg = 0;
int rc;
char *sql_insert;
double i = 1;
/* Convert Double into String */
stringstream NumberString;
NumberString << temp;
string stringtemp = NumberString.str();
NumberString << humidy;
string stringhumidy = NumberString.str();
NumberString << intervall;
string stringintervall = NumberString.str();
NumberString << i;
string stringi = NumberString.str();
string stringname = name;
string stringemail = email;
/* Open database */
rc = sqlite3_open("test.db", &db);
if( rc ){
fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
exit(0);
}else{
fprintf(stderr, "Opened database successfully\n");
}
/* This INSERT INTO command works fine
sql_insert = "INSERT INTO einstellungen (ID,EMAIL,NAME,TEMP,INTERVALL,HUMIDY)" \
"VALUES (1, 'user#test.com', 'John Doe', -5, 50, 20 );"; */
/*
/* This INSERT INTO command doesn't work */
string sqlstatement =
"INSERT INTO einstellungen (ID, EMAIL, NAME, TEMP, INTERVALL, HUMIDY) VALUES ("
+ quotesql(stringi) + ","
+ quotesql(stringemail) + ","
+ quotesql(stringname) + ","
+ quotesql(stringtemp) + ","
+ quotesql(stringintervall) + ","
+ quotesql(stringhumidy) + ");";
*/
/* Execute SQL statement */
rc = sqlite3_exec(db, sql_insert, callback, 0, &zErrMsg);
if( rc != SQLITE_OK ){
fprintf(stderr, "SQL error: %s\n", zErrMsg);
sqlite3_free(zErrMsg);
}else{
fprintf(stdout, "Einstellungen gespeichert\n");
}
sqlite3_close(db);
return 0;
}
Does anybody know where I make a mistake?
Thanks a lot :-)
I create some cout commands after each string command.
Here is the result:
I build some cout commands between each string command:
Here the result:
Datenbank wird nun angelegt
Datenbank erfolgreich angelegt
Datenbank erfolgreich initalisiert
Stringtemp: -5
Strinhumidy: 25
Stringintervall: 500
Stringi: 1
Stringname: John Doe
Stringemail: john.doe#online.de
Opened database successfully
INSERT INTO einstellungen (ID,EMAIL,NAME,TEMP,INTERVALL,HUMIDY)VALUES
(1,'john.doe#online.de','John Doe',-5,500,25);
Einstellungen gespeichert
Your numerical values such as stringhumidy shouldn't be enclosed in quotes. If you still have a problem then print somewhere the value of the sqlstatement in order to find what the error is.
I found my mistake!
I added the following line:
char * buffer = new char[sqlstatement.length()];
strcpy(buffer,sqlstatement.c_str());
So i converted the sqlstatement (string) into the required char operator
Related
I'm working on a basic program to learn how to use SQLite3; a user gives input on a song they'd like to add to a SQLite database, and it is inserted. As far as I can seen, the insert statement I'm generating- while not pretty- is a valid statement, but once it reaches my queryDatabase() function it enters the error clause. It prints "Error in execution: ", but when it moves on to errmsg, it seems to enter into a state where nothing happens/no actual error message is printed until I enter .quit. I've tried altering the print line like cout << "ERROR EXECUTING SQL: " << errmsg << "End";, and "End" never prints.
Here is the section of code that calls the queryDatabase() function/passes the command string. args refers to a vector that contains the user input:
string sqlq;
sqlq = "INSERT INTO songs (sid, title, composer) VALUES(";
sqlq.append(args[2]); sqlq.append(", "); sqlq.append("\'"); sqlq.append(args[3]); sqlq.append("\'"); sqlq.append(", "); sqlq.append("\'"); sqlq.append(args[4]); sqlq.append("\'"); sqlq.append(");");
data.queryDatabase(sqlq);
and here is the queryDatabase() function:
sqlite3 *db;
char * errmsg = 0;
int rc;
void Data::queryDatabase(string queryString){
if(queryString.empty()) return;
const char * sqlQuery = queryString.c_str();
rc = sqlite3_exec(db, sqlQuery, callback, (void *) data, &errmsg);
if( rc != SQLITE_OK) {
cout << "Error in execution: " << errmsg;
} else {
cout << "\nSQL QUERY SUCCEEDED\n";
}
}
Both queryString and sqlQuery print INSERT INTO songs (sid, title, composer) VALUES(1905, 'Anti-rage', 'Emperor X'); which as far as I know is a valid command, as copy and pasting this when working direct in the database from terminal results in the song being added. Why might this not be inserting correctly, and why am I not being given an error message?
MODIFIED FOR MORE INFO:
Here's the callback
static int callback(
void * data, //pass through data provided to sqlite3_exec() [4th argument]
int argc, //# of cols in table row
char ** argv, //array of strings representing table row values
char ** azColName //array of strings representing column names
){
for (int i=0; i<argc; i++){
cout << argv[i] << ", ";
}
cout << "\n";
return 0;
}
I am using SQLite3 header files in my C++ program and trying to create a table and insert data onto it, it works fine on a regular input.
It shows error when I use it in a C++ loop with changing variables.
I am using the database to insert my reading from RS-232.
Here is my code:
sqlite3 *db;
char *zErrMsg = 0;
int rc;
char *sql;
std::string sql_str;
std::ostringstream temp;
std::string command;
/* Open database */
rc = sqlite3_open("test_1.db", &db);
if (rc){
fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
exit(0);
}
else{
fprintf(stderr, "Opened database successfully\n");
}
std::string str;
std::ostringstream oss;
oss << id_count; // stornig the primary id int values into a string
str = "INSERT INTO M_DATA (ID, DETAILS) VALUES(";
str += oss.str(); //copying the int primary id
str += ", '";
std::string str_t1(szBuffer); //Copying character aray to a string
str += str_t1; //concatening the string
str += "');";
//printing what the database takes
//output_file << std::endl << str << std::endl;
char * writable = new char[str.size() + 1];
std::copy(str.begin(), str.end(), writable);
writable[str.size()] = '\0'; // don't forget the terminating 0
sql = writable;
output_file << std::endl << "## SQL COMMAND : " << sql << "#" << std::endl;
// don't forget to free the string after finished using it
delete[] writable;
rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
if (rc != SQLITE_OK){
fprintf(stderr, "SQL error: %s\n", zErrMsg);
output_file << std::endl << "** SQL ERROR : " << zErrMsg << "*" << std::endl;
sqlite3_free(zErrMsg);
}
else{
fprintf(stdout, "Records created successfully\n");
}
// _sleep(3000);
sqlite3_close(db);
My issue is I have a szBuffer which changes everytime, and I have to insert it as a new entry into the table.
Is there a way to increment the Primary Key and store my string into it?
The sz buffer at a single line will give data like: For Ex:
szBuffer : ersion = 1 [SPI]: MinorVersion = 2 [SPI]: Real Time
= 1434260351 [SPI]: SR # = SBB-ST1000090
The SQL command in the string I pass is like this:
SQL COMMAND : INSERT INTO M_DATA (ID, DETAILS) VALUES(9,
'ersion = 1 [SPI]: MinorVersion = 2 [SPI]: Real Time = 1434260351
[SPI]: SR # = SBB-ST1000090');
The Error which I get is like:
SQL ERROR : near "¸”_": syntax error
I am not sure if I am doing this right or wrong.
Can we use the insert statement in a loop? Am I passing the string the right way? (It looks correct to me when I print it out.)
But why do I get an error?
Is there any better way to enter my data?
I am very new to this so I tried search the internet, but no one is doing it the way I did it.
Please help.
Many Thanks.
(Almost) never build a SQL statement via string concatenation. Use a prepared statement and bind the parameter values.
// Prepare the statement
sqlite3_stmt* stmt;
int result = sqlite3_prepare_v2(db, "INSERT INTO M_DATA (ID, DETAILS) VALUES(?, ?);", -1, &stmt, nullptr);
// TODO: Handle when result != SQLITE_OK
while(/* whatever you wanted to loop on */)
{
// Bind in the parameter values
result = sqlite3_bind_int(stmt, 1, id_count);
// TODO: Handle when result != SQLITE_OK
result = sqlite3_bind_text(stmt, 2, szBuffer, -1, SQLITE_STATIC);
// TODO: Handle when result != SQLITE_OK
// Invoke the statement
result = sqlite3_step(stmt);
// TODO: Handle when result != SQLITE_OK
// Reset the statement to allow binding variables on the next iteration
result = sqlite3_reset(stmt);
}
// Release the statement
sqlite3_finalize(stmt);
I want to read data from txt file and insert it into SQlite database table with C++. I prepared a code but it doesn't work.
Example line from my txt file is follows;
',1417392060.000000','1.245430','1.2456','1.24469','1.245000'
And code;
sqlite3 *db;
char *zErrMsgt = 0;
int rct;
int rch;
int rchi;
rct = sqlite3_open("final.db", &db);
if( rct ){
fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
exit(0);
}else{
fprintf(stdout, "Opened database successfully\n");
}
string resline;
ifstream res("Res.txt");
while(getline(res,resline)){
string sqlli = "INSERT into FOREXNEW(DATE,OPEN,HIGH,LOW,CLOSE) VALUES ("getline(res,resline)");";
rchi = sqlite3_exec(db, sqlli.c_str(), callback, 0, &zErrMsgt);
if( rchi != SQLITE_OK ){
cout << "SQL error:" << zErrMsgt;
sqlite3_free(zErrMsgt);
}}
sqlite3_close(db);
Any alternate suggestions and solutions will be appreciated as well:) Thank you.
Getline doesn't return a string; it copies it to the variable passed in the second parameter. Change the erroneous line:
string sqlli = "INSERT into FOREXNEW(DATE,OPEN,HIGH,LOW,CLOSE) VALUES ("getline(res,resline)");";
to:
string sqlli = "INSERT into FOREXNEW(DATE,OPEN,HIGH,LOW,CLOSE) VALUES ("+resline+");";
And check if it works.
sorry for my english :) Trying to improve my application I want to copy vectors directly into mysql without string, is it even possible?
FileStorage fs( ".yml", FileStorage::WRITE + FileStorage::MEMORY );
Ptr < FaceRecognizer > model0 = createmyfisherRecognizer();
model0->train( images, labels );
model0->save( fs );
void myfisher::save( FileStorage & fs ) const {
static char * host = "localhost"; /* host serwera MySQL */
static char * user = "root"; /* nazwa loginu by polaczyc sie do serwera */
static char * password = ""; /* haslo */
static char * sql_db = "fisher"; /* nazwa bazy */
static unsigned int sql_port = NULL; /* port na jakim odbiera/wysyla serwer mysql */
static char * opt_socket = NULL; /* socket name */
static unsigned int sql_flags = 0;
static MYSQL * sock; /* Wskaznik do polaczenia do MySQL */
sock = mysql_init( NULL );
if( mysql_real_connect( sock, host, user, password, sql_db, sql_port, opt_socket, sql_flags ) )
cout << "Poprawnie polaczyles sie z baza danych" << endl;
else
cout << "Blad w polaczeniu z baza danych" << endl;
fs << "num_components" << _num_components;
fs << "mean" << _mean;
fs << "eigenvalues" << _eigenvalues;
writeFileNodeList( fs, "projections", _projections );
fs << "labels" << _labels;
string buf = fs.releaseAndGetString();
fs.release();
string zapytanie = "insert into baa values (\"" + buf + "\")";
if( !mysql_query( sock, zapytanie.c_str() ) )
cout << "Poprawnie dodano" << endl;
else
cout << "Blad przy zapisywaniu" << endl;
}
Here I posted the code in question. At the moment it works in this way:
everything is saved into fs (FileStorage)
data in fs is converted to string
fs sent to database
It is known that the program would run much faster if it would be directly copied without the string to the database.
i think you can use snprintf for this, unfortunatelly since there are variable types missing i cant give you exact example.
char string[100];
snprintf(string, 100, "printe text %s,\n and integer %i", "printf", 100); //almost same as printf
I am trying to save the contents of the key and value of a map into a database table. The .dbo file is created, but nothing goes into the table. It doesn't create table but it doesn't exit. I wonder what is wrong with my code.
void names_table( std::map<std::string, unsigned int> &names ){
std::string sql;
std::string str1;
std::string str2;
std::string str3;
sqlite3_stmt *stmt;
const char *file_names = create_db_file( ); /* default to temp db */
sqlite3 *db;
sqlite3_initialize( );
int rc = sqlite3_open_v2( file_names, &db, SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE, NULL);
if ( rc != SQLITE_OK) {
sqlite3_close( db );
cout << "Error: Database cannot open!" << endl;
exit( EXIT_FAILURE);
}
sql = "CREATE TABLE IF NOT EXISTS names_table (offset INTEGER PRIMARY KEY, stname TEXT);";
sqlite3_prepare_v2(db, sql.c_str(), sql.size(), &stmt, NULL);
if (sqlite3_step(stmt) != SQLITE_DONE) cout << "Didn't Create Table!" << endl;
for (auto pm = names.begin(); pm != names.end(); pm++) {
str2 = "'" + pm->first + "'";
char tmp[15];
sprintf(tmp,"%u",pm->second);
str3 = tmp;
str1 = (((("INSERT INTO names_table VALUES(" + str3) + ", ") + str2) + ");");
std::cout << str1 << std::endl;
sql = (char *)str1.c_str();
// stmt = NULL;
rc = sqlite3_prepare_v2(db, sql.c_str(), sql.size(), &stmt, NULL);
if ( rc != SQLITE_OK) {
sqlite3_close(db);
cout << "Error: Data cannot be inserted!" << endl;
exit ( EXIT_FAILURE);
}
}
sqlite3_close( db );
}
INSERT INTO names_table VALUES(ramsar, 8329) - I hope you're aware that string literals in SQL need to be enclosed in quotes. Try this: INSERT INTO names_table VALUES('ramsar', 8329).
EDIT: Actually, your code will never do what you want, because you're not even calling sqlite3_step after sqlite3_prepare_v2, which means that you're only compiling your SQL statement, but never evaluating it. Where did you find this bad example? See here and here decent examples on how to use the SQLite C++ interface properly.
PS: Stop messing around with sprintf in C++. You have std::stringstream for it.