FastDb 简单编码运用
夹谷茂
FastDb在代码中实现，首先需要在代码中注册一个表，相当于数据库的建表。代码如下：
class Student
{
public:
char const* vc_stuid;
char const* vc_stuname;
char const* vc_sex;
dbArray< dbReference<Score> > ScoreRefs; /*一个学生对应多个成绩，所以关系是1:n*/
TYPE_DESCRIPTOR((KEY(vc_stuid, INDEXED|HASHED),
KEY(vc_stuname, HASHED),
FIELD(vc_sex),
RELATION(ScoreRefs, StuRef)
));
};
REGISTER(Student);
详细参见http://blog.csdn.net/fuyun10036/article/details/8620542中table那一节。
表建好之后就是打开数据库：
dbDatabase db;
db.open("FastDbTest") 其中FastDbTest是数据库名
插入数据：
Student stu;
stu.vc_stuid = stuid;
stu.vc_stuname = stuname;
stu.vc_sex = sex;
insert(stu);
db.commit();
查询数据：
dbCursor<Student> students; 其中Student是表名
if(students.select() >0)
{
do
{
printf("%s\t%s\t%s\t\n",students->vc_stuid,students->vc_stuname,students->vc_sex);
}while(students.next());
}
删除数据：
dbQuery q2 = "vc_stuname = ",name1;
dbCursor<Student> updatestudent(dbCursorForUpdate);
if(updatestudent.select(q2) >0)
{
updatestudent.removeAllSelected();
db.commit();
}更新记录：
if(updatestudent.select(q1) >0)
{
do
{
updatestudent->vc_stuname = "wang";
}while(students.next());
updatestudent.update();//自动提交
}附上全部代码：
// FastDb_Test_01.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <stdio.h>
#include <string.h>
#include "fastdb.h"
USE_FASTDB_NAMESPACE
class Score;
class Student
{
public:
char const* vc_stuid;
char const* vc_stuname;
char const* vc_sex;
dbArray< dbReference<Score> > ScoreRefs; /*一个学生对应多个成绩，所以关系是1:n*/
TYPE_DESCRIPTOR((KEY(vc_stuid, INDEXED|HASHED),
KEY(vc_stuname, HASHED),
FIELD(vc_sex),
RELATION(ScoreRefs, StuRef)
));
};
class Subject
{
public:
char const* vc_subid;
char const* vc_subname;
dbArray< dbReference<Score> > ScoreRefs; /*一门科目对应多个成绩，所以关系是1:n*/
TYPE_DESCRIPTOR((KEY(vc_subid, INDEXED|HASHED),
KEY(vc_subname, HASHED),
RELATION(ScoreRefs, SubRef)
));
};
class Score
{
public:
char const* vc_stuid;
char const* vc_subid;
int4 l_score;
dbReference<Student> StuRef;
dbReference<Subject> SubRef;
TYPE_DESCRIPTOR((KEY(vc_stuid, INDEXED|HASHED),
KEY(vc_subid, INDEXED|HASHED),
FIELD(l_score),
RELATION(StuRef,ScoreRefs),
RELATION(SubRef,ScoreRefs)
));
};
/* 建表 */
REGISTER(Student);
REGISTER(Subject);
REGISTER(Score);
int main()
{
const int maxStrlen = 256;
dbDatabase db;
Student stu;
Subject sub;
Score sco;
char name[101];
char name1[101];
char id[11];
char id1[4];
strcpy(name,"wangjm");
strcpy(name1,"tanghui");
dbQuery q1,q2,q3,q4,q5;
q1 = "vc_stuname =",name;
q2 = "vc_stuname = ",name1;
q3 = "vc_stuid =",id;
q4 = "vc_subid =",id;
dbCursor<Student> students;
dbCursor<Score> scores;
dbCursor<Subject> subjects;
dbCursor<Student> updatestudent(dbCursorForUpdate);
if (db.open("FastDbTest"))
{
/* 插入 */
char stuid[11];
char stuname[101];
char sex[2];
char subid[4];
char subname[101];
int score;
memset((void *)stuid,'\0',sizeof(stuid));
memset((void *)stuname,'\0',sizeof(stuname));
memset((void *)sex,'\0',sizeof(sex));
memset((void *)subid,'\0',sizeof(subid));
memset((void *)subname,'\0',sizeof(subname));
/* 1 */
strcpy(stuid,"1");
strcpy(stuname,"wangjm");
strcpy(sex,"0");
strcpy(id,stuid);
if (students.select(q3) >0 )
{
printf("this student is existed!\n");
}
else
{
stu.vc_stuid = stuid;
stu.vc_stuname = stuname;
stu.vc_sex = sex;
insert(stu);
db.commit();
printf("student infomation insert successfully!\n");
}
/* 2 */
strcpy(stuid,"2");
strcpy(stuname,"tanghui");
strcpy(sex,"1");
strcpy(id,stuid);
if (students.select(q3) >0 )
{
printf("this student is existed!\n");
}
else
{
stu.vc_stuid = stuid;
stu.vc_stuname = stuname;
stu.vc_sex = sex;
insert(stu);
db.commit();
printf("student infomation insert successfully!\n");
}
/* 3 */
strcpy(subid,"1");
strcpy(subname,"c++");
strcpy(id1,subid);
if (subjects.select(q4) >0)
{
printf("this subject is existed!\n");
}
else
{
sub.vc_subid = subid;
sub.vc_subname = subname;
insert(sub);
db.commit();
}
/* 4 */
strcpy(stuid,"1");
strcpy(subid,"1");
strcpy(id,stuid);
strcpy(id1,subid);
score = 98;
if((scores.select(q3) >0)&&(scores.select(q4) >0))
{
printf("this student's score of this subject is existed!\n");
}
else
{
if(students.select(q3) == 1)
{
sco.StuRef = students.currentId(); /* 可以引用到关联的记录，但是如果后面该关联的记录被删除，则这条记录也会引发错误 */
}
if(subjects.select(q4) ==1)
{
sco.SubRef = subjects.currentId();
}
sco.vc_stuid = stuid;
sco.vc_subid = subid;
sco.l_score = score;
insert(sco);
db.commit();
printf("score infomation insert successfully!\n");
}
/* 查询 */
if(students.select() >0)
{
do
{
printf("%s\t%s\t%s\t\n",students->vc_stuid,students->vc_stuname,students->vc_sex);
}while(students.next());
}
/*if(updatestudent.select(q1) >0)
{
//删除查询到的所有记录
updatestudent.removeAllSelected();
db.commit();
printf("this student is deleted!\n");
}*/
if(scores.select() > 0)
{
do
{
/* 如果students.at()不存在或者已经删除则会报错! */
printf("%s\t%s\t%d\t\n",students.at(scores->StuRef)->vc_stuname,subjects.at(scores->SubRef)->vc_subname,scores->l_score);
}while(scores.next());
}
/* 删除 */
/*if(updatestudent.select(q2) >0)
{
updatestudent.removeAllSelected();
db.commit();
}*/
/* 更新 */
/*
if(updatestudent.select(q1) >0)
{
do
{
updatestudent->vc_stuname = "wang";
}while(students.next());
updatestudent.update(); //自动提交
}*/
}
db.close();
/*
//关闭了之后再开启，内存中的数据就消失了(无盘模式)
if (db.open("FastDbTest"))
{
if(students.select() >0)
{
do
{
printf("%s\t%s\t%s\t\n",students->vc_stuid,students->vc_stuname,students->vc_sex);
}while(students.next());
}
}
db.close();
*/
if (Metatable.select() > 0 )
{
do
{
printf("name:%s,type:%s\n",Metatable.name,Metatable.type);
}while(Metatable.next());
}
return 0;
}
磁盘模式下，fastdb会将数据库存在内存中同时会映射一个数据库文件，一般是.fdb格式，打开数据库时，会先读取同名数据库文件。
无盘模式下，fastdb只会将数据库存入内存，打开时数据库内没有任务记录。
磁盘模式和无盘模式的切换：
1.找到config.h(D:\fastdb-361\inc\config.h)
2.#ifdef VXWORKS
#define DISKLESS_CONFIGURATION 1
#endif // VXWORKS
//DISKLESS_CONFIGURATION - only in-memory temporary database
#define DISKLESS_CONFIGURATION 1//这句话取消注释
3.然后重新编译，编译成fastdb.lib、fastdb.dll,将新生成的fastdb.lib移到lib文件夹中
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