extrafunc.c

sql数据库的实现

#include "mydb.h"


/*本函数承担着数据库的所有搜索任务
 包括由组名搜索组的ID，由学生的姓名和学号搜索学生，
并返回该生在文件中的偏移地址*/

plink search(char *pdata,int searchtype)
{	
	if(!myfileinfo)
	{
		myfileinfo=NEW(fileinfo);
		fcntl(0,READ,myfileinfo,FILEINFOSIZE);
	}
	plink linkhead=NULL,linktemp=NULL;
	if(searchtype==SEARCH_SUB)
	{
		psubinfo subtemp=myfileinfo->sub;int i;
		for(i=0;i<MAXSUBCOUNT;i++,subtemp++)
		if(subtemp->flag&&!strcmp(subtemp->sub_name,pdata))
		{
			linkhead=NEW(link);memset(linkhead,0,LINKSIZE);
			linkhead->data=subtemp->sub_id;
			linkhead->next=NULL;
		}
		return linkhead;
	}
	if(strlen(pdata)>=19)pdata[19]=0;
	if(!mystuinfo)mystuinfo=NEW(stuinfo);
	long seek=DATASEEK;
	int count=myfileinfo->stucount,i;
	for(i=0;i<count;i++,seek+=DATATRANS)
	{
		memset(mystuinfo,0,STUINFOSIZE);
		fcntl(seek,READ,mystuinfo,STUINFOSIZE);
		if(!mystuinfo->flag){i--;continue;}
		pmystu stutemp=&mystuinfo->stu_privacy;
		switch(searchtype)
		{
			case SEARCH_SCHID:
				{
					if(!strcmp(stutemp->stu_schid,pdata))
					{
						linkhead=NEW(link);
						linkhead->data=mystuinfo->stu_seek;
						linkhead->next=NULL;
						return linkhead;
					}
					break;
				}
			case SEARCH_NAME:
				{
					if(!strcmp(stutemp->stu_name,pdata))
					{
						linktemp=NEW(link);
						linktemp->data=mystuinfo->stu_seek;
						linktemp->next=linkhead;
						linkhead=linktemp;
					}
					break;
				}
			default:return NULL;
		}
	}
	return linkhead;
}





/*
本函数将二进制的数据库文件以文本模式重写
使得二进制数据库文件中的内容透明化，同时
便于及时发现数据库中的变量异常
*/
void showfile()
{
	FILE *ftest=fopen(INFOPATH,"w+");
	if(!ftest)seterr("showfile:ftest null");
	if(!myfileinfo)
	{
		myfileinfo=NEW(fileinfo);
		fcntl(0,READ,myfileinfo,FILEINFOSIZE);
	}
	fprintf(ftest,"fileinfo\t\t:\n");
	fprintf(ftest,"stucount\t\t:%d\n",myfileinfo->stucount);
	fprintf(ftest,"countmax\t\t:%d\n",myfileinfo->countmax);
	fprintf(ftest,"subcount\t\t:%d\n",myfileinfo->subcount);
	fprintf(ftest,"spacecount\t\t:%d\n",myfileinfo->spacecount);
	int i=0,j=0;
	fprintf(ftest,"\nseek:\n");
	for(i=0;i<MAXSPACECOUNT;i++)
	{
		fprintf(ftest,"%ld\t",myfileinfo->seek[i]);j++;
		if(j>=10){fprintf(ftest,"\n");j=0;}
	}
	fprintf(ftest,"\n\nsubinfo:\n");
	psubinfo subtemp=myfileinfo->sub;
	fprintf(ftest,"\tflag\t\tsub_id\t\tsub_term\t\tsub_rate\t\tsub_name\n");
	for(i=0;i<MAXSUBCOUNT;i++,subtemp++)
	{
		fprintf(ftest,"\t%d\t\t",subtemp->flag);
		fprintf(ftest,"%d\t\t",subtemp->sub_id);
		fprintf(ftest,"%d\t\t\t",subtemp->sub_term);
		fprintf(ftest,"%3.1f\t\t\t",subtemp->sub_rate);
		fprintf(ftest,"%s\n",subtemp->sub_name);
	}
	fprintf(ftest,"\nstudent info :\n\n");
	fseek(fp,0L,SEEK_END);
	long size=ftell(fp),seek=DATASEEK;
	int allcount=(size-FILEINFOSIZE)/DATATRANS;
	if(!mystuinfo)mystuinfo=NEW(stuinfo);
	psubmark marktemp=NULL;
	pmystu stutemp=NULL;
	for(i=0;i<allcount;i++,seek+=DATATRANS)
	{
		memset(mystuinfo,0,STUINFOSIZE);
		fcntl(seek,READ,mystuinfo,STUINFOSIZE);
		stutemp=&mystuinfo->stu_privacy;
		fprintf(ftest,"flag\t\t:\t%d\n",mystuinfo->flag);
		fprintf(ftest,"stu_sysid\t:\t%d\n",mystuinfo->stu_sysid);
		fprintf(ftest,"stu_name\t:\t%s\n",stutemp->stu_name);
		fprintf(ftest,"stu_schid\t:\t%s\n",stutemp->stu_schid);
		if(stutemp->stu_sex)fprintf(ftest,"stu_sex\t\t:\t女\n");
		else fprintf(ftest,"stu_sex\t\t:\t男\n");
		fprintf(ftest,"stu_major\t:\t%s\n",stutemp->stu_major);
		fprintf(ftest,"stu_seek\t:\t%ld\n",mystuinfo->stu_seek);
		fprintf(ftest,"stu_markcount\t:\t%d\n",mystuinfo->stu_markcount);
		fprintf(ftest,"stu_avemark\t:\t%4.1f\n",mystuinfo->stu_avemark);
		fprintf(ftest,"stumark:\n");
		marktemp=mystuinfo->stu_mark;
		fprintf(ftest,"\t\tflag\t\t\t\t\tsub_id\t\t\t\t\tsub_mark\n");
		for(j=0;j<MAXSUBCOUNT;j++)
		{
			fprintf(ftest,"\t\t%d\t\t\t",marktemp[j].flag);
			fprintf(ftest,"\t\t%d\t\t\t",marktemp[j].sub_id);
			fprintf(ftest,"\t\t%4.1f\n",marktemp[j].sub_mark);
		}
	}
	fclose(ftest);
}




//本函数用于单链表排序
plink sortlink(plink linkhead,int sorttype)	
{
    if(!linkhead||!linkhead->next)return linkhead;
	plink q=linkhead,s,temp=NEW(link);
    temp->next=q ;int flag1,flag2,flag;
	flag=sorttype-SORT_INCLINE;
    while(linkhead&&linkhead->next)
    {
        while(temp-linkhead)		
        {
            s=linkhead->next ;
            if(!s)break ;
			flag1=s->mark<q->mark;
			flag2=s->mark<temp->next->mark;
            if(flag?!flag1:flag1)
            {
				linkhead->next=s->next ;
				s->next=q ;
				q=s ;
				temp=q ;
			}
            else if(flag?!flag2:flag2)
            {
				linkhead->next=s->next ;
				s->next=temp->next ;
				temp->next=s ;
				temp=q ;
			}
            else temp=temp->next ;
        }
        linkhead=linkhead->next ;
        temp=q ;
    }
    return q ;
}



//建立单链表
plink makelink(plink linkhead,double mark,long seek)
{
	plink linktemp=NEW(link);
	linktemp->mark=mark;
	linktemp->next=linkhead;
	linktemp->data=seek;
	linkhead=linktemp;
	return linkhead;
}



//本函数用于将每个学生某科的成绩建立单链表
plink marklink(int markid)
{
	if(markid<-1||markid>MAXSUBCOUNT)return NULL;
	if(!markid)return NULL;
	plink linkhead=NULL;
	if(!myfileinfo)
	{
		myfileinfo=NEW(fileinfo);
		fcntl(0,READ,myfileinfo,FILEINFOSIZE);
	}
	if(!mystuinfo)mystuinfo=NEW(stuinfo);
	int stucount=myfileinfo->stucount,i;
	long seek=DATASEEK;
	psubmark marktemp=mystuinfo->stu_mark;
	for(i=0;i<stucount;i++,seek+=DATATRANS)
	{
		memset(mystuinfo,0,STUINFOSIZE);
		fcntl(seek,READ,mystuinfo,STUINFOSIZE);
		if(!mystuinfo->flag){i--;continue;}
		if(!mystuinfo->stu_markcount)continue;
		if(markid==-1)
		linkhead=makelink(linkhead,mystuinfo->stu_avemark,mystuinfo->stu_seek);
		else if(marktemp[markid-1].flag)
		linkhead=makelink(linkhead,marktemp[markid-1].sub_mark,mystuinfo->stu_seek);
	}
	return linkhead;
}


//释放整条链表的空间
void freelink(plink linkhead)
{
	if(!linkhead)return;
	plink linktemp=linkhead;
	while(linkhead)
	{
		linktemp=linkhead->next;
		free(linkhead);
		linkhead=linktemp;
	}
}



//本函数用于测试链表中的变量是否异常之用
void showlink(plink linkhead)
{
	int j=1;
	while(linkhead&&j)
	{
		printf("mark:%5.1f\t\t",linkhead->mark);
		printf("seek:%ld\t\t",linkhead->data);
		printf("next:%p\t\n",linkhead->next);
		linkhead=linkhead->next;
		printf("input:");
		scanf("%d",&j);
	}
}


//本函数用于测试该类型的结构体中变量值是否异常之用
void showsubmark(psubmark marktemp)
{
	printf("flag:%d\t",marktemp->flag);
	printf("subid:%d\t",marktemp->sub_id);
	printf("submark:%5.1f\n",marktemp->sub_mark);
}


//本函数用于测试该类型的结构体中变量值是否异常之用
void showsubinfo(psubinfo subtemp)
{
	printf("\nflag:%d\t",subtemp->flag);
	printf("sub_id:%d\t",subtemp->sub_id);
	printf("subterm:%d\n",subtemp->sub_term);
	printf("rate:%3.1f\t",subtemp->sub_rate);
	printf("name:%s\n",subtemp->sub_name);
	
}