sqlite数据库在程序打包之前清除所有表中的数据

最新推荐文章于 2024-04-13 22:16:35 发布

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本文介绍了一个用于自动清除SQLite数据库中所有表数据的类，该类通过加载SQLite库、打开数据库、执行SQL语句并关闭数据库来实现自动清理功能，简化了数据维护过程。

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程序中使用sqlite数据库存储数据，每次打包程序之前都要查看一下数据表中是否有垃圾数据，手动清除，很麻烦，所有编写了一个自动清除sqlite数据库中的所有表的数据的类

代码如下，欢迎指正：

#pragma once

#include <string>
using namespace std;

//数据库中表的名称
extern string g_tablename;
//数据库中表的内容
extern int g_tablecnt;

//导出Sqlite3数据库函数
typedef int (__cdecl *MYSQLITEOPEN)(const char* filename,HANDLE **dbHandle);
typedef int (__cdecl *MYSQLITEEXEC)(HANDLE *dbHandle,const char *sql,int (*callback)(void*,int,char**,char**),void *,char **errmsg);
typedef int (__cdecl *MYSQLITEPREP)(HANDLE *dbHandle,const char *sql,int nBytes,char **ppStmt , char **pzTail);
typedef int (__cdecl *MYSQLITESTEP)(char *ppStmt);
typedef int (__cdecl *MYSQLITECLOSE)(HANDLE *dbHandle);
int printresult(void *data,int n_columns,char **column_values,char **column_names);

class COpsqlitedb
{
public:
	COpsqlitedb(void);
	~COpsqlitedb(void);
public:
	int LoadSQLiteLibrary(wchar_t* dbpath);
	int FreeSQLiteLibrary();
	int OpenSqlitedb(wchar_t *dbpath);
	int CloseSqlitedb();
	int ExecSqlState(char* sqlstate,bool bneedcallback);
	int CleartableData();
private:
	HANDLE *m_dbhandle;
	HINSTANCE m_Hinstance;
	MYSQLITEOPEN m_SqliteOpen;
	MYSQLITEEXEC  m_SqliteExec;
	MYSQLITEPREP m_Sqliteprep;
	MYSQLITECLOSE m_SqliteClose;
};

#include "StdAfx.h"
#include "opsqlitedb.h"

//数据库中表的名称
string g_tablename="";
//数据库中表的内容
int g_tablecnt=0;

COpsqlitedb::COpsqlitedb(void)
{
	m_dbhandle=NULL;
	m_Hinstance = NULL;
	m_SqliteOpen=NULL;
	m_SqliteExec=NULL;
	m_Sqliteprep=NULL;
	m_SqliteClose=NULL;
}

COpsqlitedb::~COpsqlitedb(void)
{
	m_dbhandle=NULL;
	m_Hinstance = NULL;
	m_SqliteOpen=NULL;
	m_SqliteExec=NULL;
	m_Sqliteprep=NULL;
	m_SqliteClose=NULL;
}


int COpsqlitedb::LoadSQLiteLibrary(wchar_t* dbpath)
{
	bool FileExistRes = PathFileExists(dbpath);
	if(!FileExistRes)
	{
		return -1;
	}
	m_Hinstance = LoadLibrary(dbpath);
	if(m_Hinstance!=NULL)
	{
		m_SqliteOpen =(MYSQLITEOPEN)GetProcAddress(m_Hinstance,"sqlite3_open");
		m_Sqliteprep = (MYSQLITEPREP)GetProcAddress(m_Hinstance,"sqlite3_prepare_v2");
		m_SqliteExec = (MYSQLITEEXEC)GetProcAddress(m_Hinstance,"sqlite3_exec");
		m_SqliteClose =(MYSQLITECLOSE)GetProcAddress(m_Hinstance,"sqlite3_close"); 

		if((NULL==m_SqliteOpen) || (NULL==m_Sqliteprep) || (NULL==m_SqliteExec)||(NULL==m_SqliteClose))
		{
			return -1;
		}	
	}
	return 0;
}

int COpsqlitedb::FreeSQLiteLibrary()
{
	FreeLibrary(m_Hinstance);
	m_Hinstance = NULL;
	return 0;
}

int COpsqlitedb::OpenSqlitedb(wchar_t *dbpath)
{
	if (m_SqliteOpen)
	{
		int len = WideCharToMultiByte(CP_UTF8,0,dbpath,-1,NULL,0,NULL,NULL);
		char *dbpathA = new char[len+1];
		memset(dbpathA,0,len+1);
		WideCharToMultiByte(CP_UTF8,0,dbpath,-1,dbpathA,len,NULL,NULL);
		dbpathA[len]='\0';
		int rc = (m_SqliteOpen)(dbpathA,&m_dbhandle);
		delete[] dbpathA;
		return rc;
	}
	else
		return -1;
}

int COpsqlitedb::CloseSqlitedb()
{
	return (m_SqliteClose)(m_dbhandle);
}

int printresult(void *data,int n_columns,char **column_values,char **column_names)
{
	g_tablecnt += n_columns;
	for (int i=0;i<n_columns;i++)
	{
		//MessageBoxA(NULL,column_names[i],column_values[i],0);
		g_tablename += column_values[i];
		g_tablename+=";";
	}
	return 0;
}

int COpsqlitedb::ExecSqlState(char* sqlstate,bool bneedcallback)
{
	char *zErrMsg = '\0';
	int res =  -1;
	if (bneedcallback)
	{
		g_tablecnt = 0;
		g_tablename = "";
		res=(m_SqliteExec)(m_dbhandle,sqlstate,printresult,0,&zErrMsg);
		MessageBoxA(NULL,g_tablename.c_str(),"msg",0);
	}
	else
	{
      res=(m_SqliteExec)(m_dbhandle,sqlstate,0,0,&zErrMsg);
	}
	if (res)
	{
		MessageBoxA(NULL,"operator db fail",zErrMsg,0);
	}
	return res;
}

int COpsqlitedb::CleartableData()
{
	int pos= 0;
	int res =  -1;
	unsigned  int size=g_tablename.size();
	for(unsigned  int i=0; i<size; i++)
	{
		pos=g_tablename.find(";",i);
		if(pos<size)
		{
			string s=g_tablename.substr(i,pos-i);
			char *zErrMsg = '\0';
			char sqlstate[MAX_PATH] = {"0"};
			sprintf_s(sqlstate,sizeof(sqlstate),"DELETE FROM %s",s.c_str());
			res=(m_SqliteExec)(m_dbhandle,sqlstate,0,0,&zErrMsg);
			i=pos;
		}
	}
	return res;
}

调用代码如下:

int dropdbdata(wchar_t *dllpath,wchar_t* dbpath)
{
	COpsqlitedb operatedb;
	int res = operatedb.LoadSQLiteLibrary(dllpath);
	if (res)
	{
		return res;
	}
	res = operatedb.OpenSqlitedb(dbpath);
	if (res)
	{
		operatedb.FreeSQLiteLibrary();
		return res;
	}
	res = operatedb.ExecSqlState("select name from sqlite_master where type='table' order by name;",true);
	if (res)
	{
		operatedb.CloseSqlitedb();
		operatedb.FreeSQLiteLibrary();
		return res;
	}
	res = operatedb.CleartableData();
	if (res)
	{
		operatedb.CloseSqlitedb();
		operatedb.FreeSQLiteLibrary();
		return res;
	}
	res = operatedb.CloseSqlitedb();
	res = operatedb.FreeSQLiteLibrary();
	return res;
}