sqlite3的使用

splite.hpp

C++ 复制代码

/*
   封装实现一个sqliteHelper类，提供简单的sqlite数据库接口，完成数据的基础增删改查操作
   1.创建/打开数据库
   2.针对打开的数据库进行操作
       1.表的操作
       2.数据的操作
   3.关闭数据库
*/

#include <iostream>
#include <string>
#include <vector>
#include <sqlite3.h>

class SqliteHelper
{
    public:
        typedef int(*SqliteCallback)(void*,int ,char**,char**);
        SqliteHelper(const std::string &dbfile):_dbfile(dbfile),_handler(nullptr){}
        bool open(int safe_level=SQLITE_OPEN_FULLMUTEX)
        {
            //int sqlite3_open_v2(const char *filename, sqlite3 **ppDb, int flags, const char *zVfs );
            int ret=sqlite3_open_v2(_dbfile.c_str(),&_handler,SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE | safe_level,nullptr);
            if(ret!=SQLITE_OK)
            {
                std::cout<<"创建/打开sqlite数据库失败";
                std::cout<<sqlite3_errmsg(_handler)<<std::endl;
                return false;
            }
            return true;
        }
        bool exec(const std::string &sql,SqliteCallback cb,void *arg)
        {
            //int sqlite3_exec(sqlite3*, char *sql, int (*callback)(void*,int,char**,char**),  void* arg, char **err)
            int ret=sqlite3_exec(_handler,sql.c_str(),cb,arg,nullptr);
            if(ret!=SQLITE_OK)
            {
                std::cout<<sql<<std::endl;
                std::cout<<"执行语句失败！";
                std::cout<<sqlite3_errmsg(_handler)<<std::endl;
                return false;
            }
            return true;
        }
        void close()
        {
           // int sqlite3_close_v2(sqlite3*)
           if(_handler) sqlite3_close_v2(_handler);
        }
    private:
        std::string _dbfile;
        sqlite3* _handler;
};

main.cc

C++ 复制代码

#include "sqlite.hpp"
#include <cassert>

int select_stu_callback(void*arg,int col_count,char**result,char**fields_name)
{
    std::vector<std::string> *arry=(std::vector<std::string>*)arg;
    arry->push_back(result[0]);
    return 0;//必须有！
}
int main()
{
    SqliteHelper helper("./test.db");
    //1.打开/创建库文件
    assert(helper.open());
    //2.创建表，学生信息：学号，姓名，年龄
    const char* ct="create table if not exists student(sn int primary key,name varchar(32),age int)";
    assert(helper.exec(ct,nullptr,nullptr));
    //3.新增数据，删除，修改，查询
    //const char* insert_sql="insert into student values(1,'小明',18),(2,'小黑',19),(3,'小红',18)";
    //assert(helper.exec(insert_sql,nullptr,nullptr));
    //const char *update_sql="update student set name ='张小明' where sn=1";
    //assert(helper.exec(update_sql,nullptr,nullptr));
    //const char *delete_sql="delete from student where sn=3";
    //assert(helper.exec(delete_sql,nullptr,nullptr));
    const char *select_sql="select name from student ;";
    std::vector<std::string> arry;
    assert(helper.exec(select_sql,select_stu_callback,&arry));
    for(auto &name: arry)
    {
        std::cout<<name<<std::endl;
    }
    //4.关闭数据库
    helper.close();
    return 0;
}

makefile

makefile 复制代码

main:main.cc
	g++ -std=c++11 $^ -o $@ -lsqlite3