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最新推荐文章于 2025-12-03 13:04:04 发布

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#数据库

本文介绍了一个用于简化 SQLite 数据库操作的 C++ 类库——SQLiteWrapper。该类库提供了易于使用的接口来执行 SQL 语句，包括绑定参数、执行查询、获取结果集等功能，并支持事务管理。适用于希望在 C++ 应用中快速集成 SQLite 功能的开发者。

/*
SQLiteWrapper.h

   This source code is provided 'as-is', without any express or implied
   warranty. In no event will the author be held liable for any damages
   arising from the use of this software.

   Permission is granted to anyone to use this software for any purpose,
   including commercial applications, and to alter it and redistribute it
   freely, subject to the following restrictions:

   1. The origin of this source code must not be misrepresented; you must not
      claim that you wrote the original source code. If you use this source code
      in a product, an acknowledgment in the product documentation would be
      appreciated but is not required.

2. Altered source versions must be plainly marked as such, and must not be
misrepresented as being the original source code.

3. This notice may not be removed or altered from any source distribution.

René Nyffenegger rene.nyffenegger@adp-gmbh.ch
*/

#ifndef SQLITE_WRAPPER_H__
#define SQLITE_WRAPPER_H__

#include <string>
#include <vector>

#include "sqlite3/sqlite3.h"

class SQLiteStatement {
private:
    // SQLiteStatement's ctor only to be called by SQLiteWrapper
    friend class SQLiteWrapper;
    SQLiteStatement(std::string const& statement, sqlite3* db);

public:
SQLiteStatement();

    enum dataType {
      INT = SQLITE_INTEGER,
      FLT = SQLITE_FLOAT ,
      TXT = SQLITE_TEXT   ,
      BLB = SQLITE_BLOB   ,
      NUL = SQLITE_NULL   ,
    };

dataType DataType(int pos_zero_indexed);

int ValueInt (int pos_zero_indexed);
std::string ValueString(int pos_zero_indexed);

// SQLiteStatement(const SQLiteStatement&);
~SQLiteStatement();

//SQLiteStatement& operator=(SQLiteStatement const&);

    bool Bind    (int pos_zero_indexed, std::string const& value);
    bool Bind    (int pos_zero_indexed, double             value);
    bool Bind    (int pos_zero_indexed, int                value);
    bool BindNull(int pos_zero_indexed);

bool Execute();

bool NextRow();

    /*   Call Reset if not depending on the NextRow cleaning up.
         For example for select count(*) statements*/
    bool Reset();

bool RestartSelect();

private:
//void DecreaseRefCounter();

//int* ref_counter_; // not yet used...
sqlite3_stmt* stmt_;
};

class SQLiteWrapper {
public:
SQLiteWrapper();

bool Open(std::string const& db_file);

    class ResultRecord {
      public:
        std::vector<std::string> fields_;
    };

    class ResultTable {
      friend class SQLiteWrapper;
      public:
        ResultTable() : ptr_cur_record_(0) {}

        std::vector<ResultRecord> records_;

         ResultRecord* next() {
          if (ptr_cur_record_ < records_.size()) {
            return &(records_[ptr_cur_record_++]);
          }
          return 0;
        }

      private:
         void reset() {
           records_.clear();
           ptr_cur_record_=0;
         }

      private:
        unsigned int ptr_cur_record_;
    };

    bool SelectStmt           (std::string const& stmt, ResultTable& res);
    bool DirectStatement      (std::string const& stmt);
    SQLiteStatement* Statement(std::string const& stmt);

std::string LastError();

    // Transaction related
    bool Begin   ();
    bool Commit ();
    bool Rollback();

private:

static int SelectCallback(void *p_data, int num_fields, char **p_fields, char **p_col_names);

sqlite3* db_;
};

#endif