对Sqlite数据库C API的简单封装

1. 头文件

 

#pragma once #include <string> #include <sstream> using namespace std; #include "Sqlite/sqlite3.h" #pragma comment(lib, "Sqlite/sqlite3.lib") class CResultSet { public: friend class CSqliteMgr; public: CResultSet(); ~CResultSet(); public: int GetColumnNum(); // 获得结果数目 int GetRecordCount(); public: int GetInt(int row, int column); string GetString(int row, int column); private: // 获取对应行列的结果 char * GetAt(int row, int column); private: char **szResult; int nRow; int nColumn; }; class CSqliteMgr { public: CSqliteMgr(string filename); ~CSqliteMgr(); public: int Execute(const char *sql); int Execute(string sql); CResultSet * ExecuteQuery(string sql); public: void FreeResultSet(CResultSet *rs); public: void Begin(); void Commit(); void Rollback(); private: void print_error(char *error); private: sqlite3 *m_conn; };

2. 源文件

 

#include "stdafx.h" #include "SqliteMgr.h" CResultSet::CResultSet() { } CResultSet::~CResultSet() { ::sqlite3_free_table(szResult); } int CResultSet::GetColumnNum() { return nColumn; } int CResultSet::GetRecordCount() { return nRow; } int CResultSet::GetInt(int row, int column) { return atoi(GetAt(row, column)); } string CResultSet::GetString(int row, int column) { return string(GetAt(row, column)); } char * CResultSet::GetAt(int row, int column) { return szResult[(row + 1) * nColumn + column]; } CSqliteMgr::CSqliteMgr(string filename) { int nRet = ::sqlite3_open(filename.c_str(), &m_conn); if (nRet != SQLITE_OK) { print_error("sqlite3_open fail"); } } CSqliteMgr::~CSqliteMgr() { ::sqlite3_close(m_conn); } int CSqliteMgr::Execute(const char *sql) { char *error_msg = NULL; int nRet = ::sqlite3_exec(m_conn, sql, 0, 0, (char **) &error_msg); if (nRet != SQLITE_OK) { print_error(error_msg); return -1; } return nRet; } int CSqliteMgr::Execute(string sql) { return Execute(sql.c_str()); } CResultSet * CSqliteMgr::ExecuteQuery(string sql) { char *error_msg = NULL; CResultSet *pRs = new CResultSet; int nRet = ::sqlite3_get_table(m_conn, sql.c_str(), &pRs->szResult, &pRs->nRow, &pRs->nColumn, (char **) &error_msg); if (nRet != SQLITE_OK) { print_error(error_msg); return NULL; } return pRs; } void CSqliteMgr::FreeResultSet(CResultSet *rs) { if (rs != NULL) { delete rs; rs = NULL; } } void CSqliteMgr::Begin() { Execute("BEGIN TRANSACTION"); } void CSqliteMgr::Commit() { Execute("COMMIT TRANSACTION"); } void CSqliteMgr::Rollback() { Execute("ROLLBACK TRANSACTION"); } void CSqliteMgr::print_error(char *error) { char szError[128]; memset(szError, 0, 128); sprintf(szError, "sqlite error: %s/n", error); OutputDebugStringA(szError); sqlite3_free(error); }

3. 测试代码

#include <vector> #include <string> using namespace std; #include "SqliteMgr.h" #include "Tools.h" struct cRecord { int id; string name; int age; }; int _tmain(int argc, _TCHAR* argv[]) { SqliteMgr mgr("test.db"); if (false) { mgr.Execute("create table test([id] integer primary key autoincrement, [name] text, [age] int);"); char buf[256]; memset(buf, 0, 256); for (int i = 0; i < 100; ++i) { sprintf(buf, "insert into test(name, age) values(/"tom%d/", %d)", i + 1, i + 20); mgr.Execute(buf); } } else { ResultSet *rs = mgr.ExecuteQuery("select id, name, age from test"); vector<cRecord> records; for (int i = 0; i < rs->GetRecordCount(); ++i) { cRecord record; record.id = rs->GetInt(i, 0); record.name = CTools::utf8_2_ansi(rs->GetString(i, 1).c_str()); record.age = rs->GetInt(i, 2); records.push_back(record); } mgr.FreeResultSet(rs); } return 0; }