SQLite3單例模式(C++)
阿新 • 來源:網路 • 發佈:2021-05-07
注意:這程式碼只能在linux底下執行。
.h 檔案 (我的檔案是Mysql.h)
#ifndef MYSQL_H
#define MYSQL_H
#include <sqlite3.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <iostream>
using namespace std;
class MySql
{
public:
static MySql *Instance() //獲取唯一單例物件
{
if(!m_sql)
m_sql = new MySql();
return m_sql;
}
void Init(const char* fileName); //初始化
void InsertData(); //插入資料
void SelectData(int id); //通過id查詢資料
private:
MySql(); //私有 防止外部呼叫
~MySql();
static MySql* m_sql; //靜態指標儲存單例物件
static sqlite3 * db; //資料庫類指標
char *Sql_statement; //存放執行語句
sqlite3_stmt *stmt; //標記資料庫的執行資訊
int rc; //執行返回結果
};
#endif // MYSQL_H
.cpp檔案 (我的檔案是MySql.cpp)
#include "MySql.h"
sqlite3 *MySql::db;
MySql *MySql::m_sql = NULL;
MySql::MySql()
{
Sql_statement = new char[1024];
memset(Sql_statement,0,1024);
this->Init("data.db");
}
MySql::~MySql()
{
delete []this->Sql_statement;
}
//初始化,開啟資料庫、建立表
void MySql::Init(const char* fileName)
{
this->rc = sqlite3_open(fileName,&db);
if(this->rc == SQLITE_OK)
{
strcpy(this->Sql_statement,"create table student(id int primary key,name text,age int)");
this->rc = sqlite3_exec(db,Sql_statement,NULL,NULL,&errMes);
if(rc == SQLITE_OK)
{
printf("Success to create table!\n");
}
memset(Sql_statement,0,1024);
}
}
//向表中插入資料
void MySql::InsertData()
{
strcpy(this->Sql_statement,"insert into student values(1,'zhangsan',20)");
sqlite3_exec(db,this->Sql_statement,NULL,NULL,&errMes);
strcpy(this->Sql_statement,"insert into student values(2,'lisi',19)");
sqlite3_exec(db,this->Sql_statement,NULL,NULL,&errMes);
if(rc == SQLITE_OK)
{
printf("Success to insert data!\n");
}
memset(Sql_statement,0,1024);
}
//通過id查詢資料
void MySql::SelectData(int id)
{
const unsigned char *name;
int nid = 0;
int age = 0;
sprintf(this->Sql_statement,"select * from student where id = %d",id);
sqlite3_prepare(db,this->Sql_statement,-1,&this->stmt,NULL);
while(sqlite3_step(this->stmt) == SQLITE_ROW)
{
nid = sqlite3_column_int(this->stmt, 0);
name = sqlite3_column_text(this->stmt, 1);
age = sqlite3_column_int(this->stmt, 2);
printf("name:%s ,id:%d ,age:%d\n",name,nid,age);
}
}
main.cpp檔案
#include "MySql.h"
#include <iostream>
using namespace std;
int main()
{
MySql::Instance()->InsertData();
MySql::Instance()->SelectData(1);
return 0;
}
最後把這三個檔案放在linux的同一目錄底下,然後通過makefile工具進行編譯。
MakeFile檔案
ELF=main
CC=g++
src=$(wildcard *.cpp)
objects=$(src:.cpp=.o)
$(ELF):$(objects)
$(CC) $^ -o [email protected] -lsqlite3 #注意這裡記得加-lsqlite3
$(objects):
clean:
rm -f $(objects) $(ELF)
(不會Makefile的可以看我部落格:MakeFile工具使用)
編譯結果:

