【发布时间】：2021-01-12 01:32:19
【问题描述】：
我正在尝试使用 sqlite3 数据库创建一个类，其方法应在用户将文件添加到应用程序时将数据插入表中，但它没有按预期工作，
void Database::InsertSample(int Favorite, std::string Filename,
std::string SamplePack, int Channels, int Length,
int SampleRate, int Bitrate, std::string Comment,
std::string Path)
{
try
{
rc = sqlite3_open("Samples.db", &DB);
sql = "INSERT INTO SAMPLES (FAVORITE, FILENAME, SAMPLEPACK, CHANNELS, \
LENGTH, SAMPLERATE, BITRATE, BITSPERSAMPLE, PATH) \
VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?);";
rc = sqlite3_prepare_v2(DB, sql.c_str(), 0, &stmt, 0); // create the prepared statement
rc = sqlite3_bind_int(stmt, 1, Favorite);
rc = sqlite3_bind_text(stmt, 2, Filename.c_str(), Filename.size(), SQLITE_STATIC);
rc = sqlite3_bind_text(stmt, 3, SamplePack.c_str(), SamplePack.size(), SQLITE_STATIC);
rc = sqlite3_bind_int(stmt, 4, Channels);
rc = sqlite3_bind_text(stmt, 5, Filename.c_str(), Filename.size(), SQLITE_STATIC);
rc = sqlite3_bind_int(stmt, 6, Length);
rc = sqlite3_bind_int(stmt, 7, SampleRate);
rc = sqlite3_bind_int(stmt, 8, Bitrate);
rc = sqlite3_bind_text(stmt, 9, Comment.c_str(), Comment.size(), SQLITE_STATIC);
rc = sqlite3_bind_text(stmt, 10, Path.c_str(), Path.size(), SQLITE_STATIC);
rc = sqlite3_step(stmt);
rc = sqlite3_exec(DB, Sample.c_str(), NULL, 0, &ErrorMessage);
if (rc != SQLITE_OK)
{
std::cerr << "Error! Cannot insert data into table." << std::endl;
sqlite3_free(ErrorMessage);
}
else
{
std::cout << "Data inserted successfully." << std::endl;
}
sqlite3_close(DB);
}
catch (const std::exception &exception)
{
std::cerr << exception.what();
}
}
但这失败了，抛出错误语句“错误！无法将数据插入表中。”。我在这里做错了吗？
我在另一个类中使用这个函数，
void Browser::OnClickDirCtrl(wxCommandEvent& event)
{
TagLib::FileRef File (DirCtrl->GetFilePath());
TagLib::String Artist = File.tag()->artist();
TagLib::String Album = File.tag()->album();
TagLib::String Genre = File.tag()->genre();
TagLib::String Title = File.tag()->title();
TagLib::String Comment = File.tag()->comment();
int Bitrate = File.audioProperties()->bitrate();
int Channels = File.audioProperties()->channels();
int Length = File.audioProperties()->lengthInMilliseconds();
int LengthSec = File.audioProperties()->lengthInSeconds();
int SampleRate = File.audioProperties()->sampleRate();
wxVector<wxVariant> Data;
Data.clear();
Data.push_back(false);
Data.push_back(TagLibTowx(Title));
Data.push_back(TagLibTowx(Artist));
Data.push_back(wxString::Format("%d",Channels));
Data.push_back(wxString::Format("%d",LengthSec));
Data.push_back(wxString::Format("%d",SampleRate));
Data.push_back(wxString::Format("%d",Bitrate));
Data.push_back(TagLibTowx(Comment));
SampleListView->AppendItem(Data);
db.InsertSample(0, Title.to8Bit(), Artist.to8Bit(), Channels, Length, SampleRate, Bitrate, Comment.to8Bit(), DirCtrl->GetFilePath().ToStdString());
}
这只是应该将文件添加到数据库的函数的一部分。如您所见，我将文件的路径存储在数据库中，这是项目所需的重要数据。
/---------/
编辑：添加一个简短的示例，
main.cpp
#include "testdb.hpp"
int main()
{
Database db;
db.InsertData("Hello, World!");
return 0;
}
testdb.hpp
#include <sqlite3.h>
#include <string>
class Database
{
public:
Database();
~Database();
public:
sqlite3* DB;
int rc;
char* ErrorMessage;
std::string Test;
std::string sql;
sqlite3_stmt* stmt;
public:
void InsertData(std::string Path);
};
testdb.cpp
#include <exception>
#include <iostream>
#include <string>
#include "testdb.hpp"
Database::Database()
{
/* Create SQL statement */
Test = "CREATE TABLE TEST("
"TEST TEXT NOT NULL);";
try
{
rc = sqlite3_open("Test.db", &DB);
rc = sqlite3_exec(DB, Test.c_str(), NULL, 0, &ErrorMessage);
if (rc != SQLITE_OK)
{
std::cerr << "Error! Cannot create table." << std::endl;
sqlite3_free(ErrorMessage);
}
else
{
std::cout << "Table created successfuly." << std::endl;
}
sqlite3_close(DB);
}
catch (const std::exception &exception)
{
std::cerr << exception.what();
}
}
void Database::InsertData(std::string Test)
{
try
{
rc = sqlite3_open("Test.db", &DB);
sql = "INSERT INTO TEST (PATH) VALUES (?);";
rc = sqlite3_prepare_v2(DB, sql.c_str(), 10, &stmt, 0); // create the prepared statement
// error handling goes here
rc = sqlite3_bind_text(stmt, 10, Test.c_str(), Test.size(), SQLITE_STATIC);
// error handling goes here
rc = sqlite3_step(stmt);
// error handling goes here
rc = sqlite3_finalize(stmt);
if (rc != SQLITE_OK)
{
std::cerr << "Error! Cannot insert data into table." << std::endl;
sqlite3_free(ErrorMessage);
}
else if (rc == SQLITE_BUSY)
{
std::cout << "BUSY" << std::endl;
}
else if (rc == SQLITE_DONE)
{
std::cout << "DONE" << std::endl;
}
else if (rc == SQLITE_ERROR)
{
std::cout << "ERROR" << std::endl;
}
else if (rc == SQLITE_MISUSE)
{
std::cout << "MISUSE" << std::endl;
}
else
{
std::cout << "Data inserted successfully." << ErrorMessage << std::endl;
}
sqlite3_close(DB);
}
catch (const std::exception &exception)
{
std::cerr << exception.what();
}
}
Database::~Database(){}
使用g++ main.cpp testdb.cpp -l sqlite3 -o db编译。
这里发生了同样的事情，它说数据已插入，但sqlitebrowser 中的数据库显示为空。
【问题讨论】：
-
Edit 你的问题包括整个错误信息。
-
另外，我建议创建一个更简单的示例，我们可以在这里讨论。尝试对只有一列的表执行类似操作。如果你能让它工作，那么你可以从那里添加它。如果您遇到类似的错误，那么您可以编辑您的问题以显示较小的代码，这使我们更容易看到发生了什么。
-
提示：打开一次数据库连接并在程序的整个生命周期中重复使用它，而不是每次您要插入数据时。效率更高。您也可以保存和重复使用准备好的语句。
-
@Code-Apprentice 编辑了帖子，添加了简短示例，带有文件名。
-
@apoorv569 您的简短示例是否会导致与原始示例相同的错误？