SQLite3单例模式(C++)
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SQLite3单例模式(C++)
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注意:這代碼只能在linux底下運行。
.h 文件 (我的文件是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() //獲取唯一單例對象{if(!m_sql)m_sql = new MySql();return m_sql;}void Init(const char* fileName); //初始化void InsertData(); //插入數據void SelectData(int id); //通過id查詢數據 private:MySql(); //私有 防止外部調用~MySql();static MySql* m_sql; //靜態指針保存單例對象static sqlite3 * db; //數據庫類指針char *Sql_statement; //存放執行語句sqlite3_stmt *stmt; //標記數據庫的執行信息int rc; //執行返回結果 };#endif // MYSQL_H.cpp文件 (我的文件是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,打開數據庫、創建表 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);} } //向表中插入數據 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查詢數據 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文件
#include "MySql.h" #include <iostream> using namespace std;int main() {MySql::Instance()->InsertData();MySql::Instance()->SelectData(1);return 0; }最后把這三個文件放在linux的同一目錄底下,然后通過makefile工具進行編譯。
MakeFile文件
ELF=main CC=g++ src=$(wildcard *.cpp) objects=$(src:.cpp=.o) $(ELF):$(objects)$(CC) $^ -o $@ -lsqlite3 #注意這里記得加-lsqlite3 $(objects): clean:rm -f $(objects) $(ELF)(不會Makefile的可以看我博客:MakeFile工具使用)
編譯結果:
總結
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