sqlite3增删改查C++类实现

sqlite是一款轻量级数据库，由于它的管理接口简单、速度快和稳定性高等特点。在嵌入式系统中也越来越受欢迎。这里贴出简单的使用笔记，以作记录。

sqlitehandle.h:

/*************************************************************************
> File Name: sqlitehandle.h
> Author: lius
> Mail: lius_153@163.com
> Created Time: Tue 05 Apr 2016 10:16:51 AM CST
************************************************************************/
#include<iostream>
#include<string.h>
#include<stdio.h>
#include"sqlite-3.6.18/sqlite3.h"

class sqliteHandle
{
private:
sqlite3 *conn;
public:
sqliteHandle();
~sqliteHandle();
//创建数据库
bool sqlite3OpenDb();
//创建数据库表
bool sqlite3CreateTable();
//插入数据
bool sqlite3InsertData(unsigned char (&)[1538]);
//删除数据
bool sqlite3DeleteData(unsigned char id);
//修改数据
bool sqlite3ChangeData(unsigned char (&)[1538]);
//查询数据
bool sqlite3SelectData(unsigned char (&)[1538]);
};

sqlitehandle.cpp:

/*************************************************************************
> File Name: sqlitehandle.cpp
> Author: lius
> Mail: lius_153@163.com
> Created Time: Tue 05 Apr 2016 10:17:00 AM CST
************************************************************************/
#include"sqlitehandle.h"
using namespace std;
sqliteHandle::sqliteHandle()
{
conn = NULL;
}
sqliteHandle::~sqliteHandle()
{
//关闭数据库
sqlite3_close(conn);
cout << "sqlite : sqlite close." << endl;
}
//创建数据库
bool sqliteHandle::sqlite3OpenDb()
{
//打开数据库
int result = sqlite3_open("/mytest.db",&conn);
if (result != SQLITE_OK)
{
sqlite3_close(conn);
cout << "sqlite : open sqlite failed. " << endl;
return false;
}
return true;
}
//创建数据库表
bool sqliteHandle::sqlite3CreateTable()
{
sqlite3_stmt* stmt = NULL;
const char* createTableETag = "CREATE TABLE ESTABLE(ID BLOB PRIMARY KEY, DATA BLOB)";
int len = strlen(createTableETag);
//准备创建数据表，如果创建失败，需要用sqlite3_finalize释放sqlite3_stmt对象，以防止内存泄露。
if (sqlite3_prepare_v2(conn,createTableETag,len,&stmt,NULL) != SQLITE_OK)
{
if (stmt)
sqlite3_finalize(stmt);
cout << "sqlite : Create table ETag data failed. " << endl;
return false;
}
//通过sqlite3_step命令执行创建表的语句。对于DDL和DML语句而言，sqlite3_step执行正确的返回值
//只有SQLITE_DONE，对于SELECT查询而言，如果有数据返回SQLITE_ROW，当到达结果集末尾时则返回
//SQLITE_DONE。
if (sqlite3_step(stmt) != SQLITE_DONE)
{
sqlite3_finalize(stmt);
return false;
}
//释放创建表语句对象的资源。
sqlite3_finalize(stmt);
cout << "sqlite : Succeed to create test table now." << endl;
return true;
}
//插入数据
bool sqliteHandle::sqlite3InsertData(unsigned char (&buffer)[1538])
{
const char* insertSQL1 = "INSERT INTO ESTABLE VALUES(";
unsigned char* insertSQL2 = new unsigned char[strlen(insertSQL1)/* +strlen(buffer) */+1538];//先分配一块足够的空间
strcpy((char*)insertSQL2, insertSQL1);//拷贝
strncat((char*)insertSQL2, (char*)&buffer[0], 1);//追加
strcat((char*)insertSQL2, ", '");//追加
strcat((char*)insertSQL2, (char*)&buffer[1]);//追加
strcat((char*)insertSQL2, "')");//追加

char* errmsg;
if (sqlite3_exec(conn,(const char*)insertSQL2,NULL,NULL,&errmsg) != SQLITE_OK)
{
cout << "sqlite : insert data failed. error : " << errmsg << endl;
sqlite3_free(errmsg);
return false;
}
return true;
}
//删除数据
bool sqliteHandle::sqlite3DeleteData(unsigned char id)
{
const char* deleteSQL1 = "DELETE FROM ESTABLE WHERE ID = ";
unsigned char* deleteSQL2 = new unsigned char[strlen(deleteSQL1)/* +strlen(buffer) */+1538];//先分配一块足够的空间
strcpy((char*)deleteSQL2, deleteSQL1);//拷贝
strcat((char*)deleteSQL2, (char*)&id);//追加

char* errmsg;
if (sqlite3_exec(conn,(const char*)deleteSQL2,NULL,NULL,&errmsg) != SQLITE_OK)
{
cout << "sqlite : delete data failed. error : " << errmsg << endl;
sqlite3_free(errmsg);
return false;
}
return true;
}
//修改数据
bool sqliteHandle::sqlite3ChangeData(unsigned char (&buffer)[1538])
{
if(sqlite3SelectData(buffer))
{
return false;
}
const char* changeSQL1 = "UPDATE ESTABLE SET DATA = '";
unsigned char* changeSQL2 = new unsigned char[strlen(changeSQL1)/* +strlen(buffer) */+1538];//先分配一块足够的空间
strcpy((char*)changeSQL2, changeSQL1);//拷贝
strcat((char*)changeSQL2, (char*)&buffer[1]);//追加
strcat((char*)changeSQL2, "' WHERE ID = ");//追加
strncat((char*)changeSQL2, (char*)&buffer[0], 1);//追加

char* errmsg;
if (sqlite3_exec(conn,(const char*)changeSQL2,NULL,NULL,&errmsg) != SQLITE_OK)
{
cout << "sqlite : change data failed. error : " << errmsg << endl;
sqlite3_free(errmsg);
return false;
}
return true;
}
//查询数据
bool sqliteHandle::sqlite3SelectData(unsigned char (&buffer)[1538])
{
const char* selectSQL3 = "SELECT * FROM ESTABLE";
const char* selectSQL1 = "SELECT DATA FROM ESTABLE WHERE ID = '";
unsigned char* selectSQL2=new unsigned char[strlen(selectSQL1)/* +strlen(buffer) */+1538];//先分配一块足够的空间
strcpy((char*)selectSQL2, selectSQL1);//拷贝
strncat((char*)selectSQL2, (char*)&buffer[0], 1);//追加
strcat((char*)selectSQL2, "'");//追加

char* errmsg;
char** pResult;
int nRow, nCol;
if (sqlite3_get_table(conn, (const char*)selectSQL3, &pResult, &nRow, &nCol, &errmsg) != SQLITE_OK)
{
cout << "sqlite : select data failed. error : " << errmsg << endl;
sqlite3_free(errmsg);
return false;
}
string strOut;
int nIndex = nCol;
for(int i=0;i<nRow;i++)
{
for(int j=0;j<nCol;j++)
{
memset(&buffer[1], 0 , 1538);
strOut+=pResult[j];
strOut+=":";
strOut+=pResult[nIndex];
strcat((char*)&buffer[1], pResult[nIndex]);//追加
strOut+="\n";
++nIndex;
}
}
sqlite3_free_table(pResult);

cout<<strOut<<endl;

cout<<buffer<<endl;

return true;
}

sqlitemain.cpp:

/*************************************************************************
> File Name: sqlitemain.cpp
> Author: lius
> Mail: lius_153@163.com
> Created Time: Tue 05 Apr 2016 04:35:22 PM CST
************************************************************************/

#include <iostream>
#include "sqlitehandle.h"
using namespace std;
int main()
{
sqliteHandle sql;

if(!sql.sqlite3OpenDb())
cout << "sqlite open failed!" << endl;
else
cout << "sqlite open success!" << endl;
sql.sqlite3CreateTable();
unsigned char buffer[1538] = "1hasdfhaidhf34r48hfadf34rhfaaksdhfkasdhfkasdhfkasdhfkjasdhfkjasfuyasd";
sql.sqlite3InsertData(buffer);
sql.sqlite3SelectData(buffer);
//sql.sqlite3DeleteData(buffer[0]);
//sql.sqlite3SelectData(buffer);
unsigned char buffer1[1538] = "12222222222222211111111111111112222222233333333333311111111111111111";
sql.sqlite3ChangeData(buffer1);
sql.sqlite3SelectData(buffer);
}

代码中本来想用srting来搞，但是使用的数据类型都是unsigned char.不想将类型转来转去，所以就这样操作了。

如想将类中传入定长数组改为变长数组可以采用模版函数实现。