rdbsm.c

一个用C编写的简单的关系数据库系统

/**
 * Title: RDBMS
 * Description: 〈数据库〉实验
 * Copyright: Copyright (c) 2006
 * Company: BJTU
 * @author HuangHan NO.03281159 JK0306
 * @version 1.0
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <malloc.h>
#include <time.h>
#include <ctype.h>
#include <math.h>
#include <io.h>

#define FIELD_NAME_LENGTH 8 /*最长字段名*/
#define TABLE_NAME_LENGTH 8 /*最长表名*/
#define MAX_COMMOND_LENGTH 100 /*一行命令最多字符数*/
#define MAX_COMMOND_COUNT 20 /*最大命令行数*/
#define MAX_FILED_COUNT 128 /*最多字段数*/
#define MAX_OPENED_COUNT 10 /*可以打开的最多表数*/

#define Int 'a'
#define String 'b'
#define Float 'c'

#define TRUE 1
#define FALSE 0

#define FAILED 0
#define ERROR -1
#define SUCCESS 1
#define FREE -1

#define HELP 0
#define EXIT 1
#define CREATE 2
#define OPEN 3
#define CLOSE 4
#define USE 5
#define INSERT 6
#define DELETE 7
#define SELECT 8
#define UPDATE 9
#define SEEK 10

#define LT 0
#define LE 1
#define EQ 2
#define GT 3
#define GE 4
#define NE 5

typedef struct 
{
	char dhFieldName[FIELD_NAME_LENGTH];
	char dhFieldType;
	char dhFieldLen;
	int dhFieldPos;
} DBF_STRUCT;

typedef struct dhDate
{
	unsigned char year;
	unsigned char month;
	unsigned char day;
};

typedef struct 
{
	char dhName[TABLE_NAME_LENGTH];//文件名
	int dhHandle;
	int dhID;/*文件打开后的对应打开表数组中的号码*/
	//struct dhDate dhModifyDate;//最后修改日期
	long dhRecCount;/*记录数*/
	unsigned dhSturLen;/*字段长度*/
	int dhFieldCount;/*字段数*/
	long dhRecLen;/*记录长度*/
	long dhRecNO;/*当前记录号*/
	int dhModify;/*修改标志*/
	//int * dhEof;//文件尾标志
	DBF_STRUCT dbf_struct[MAX_FILED_COUNT];/*记录结构*/
} DBF;
typedef union {
	int intType;
	float floatType;
	char * string;
} RecUnion;

void welcome();

#include "ShowRec.c"
#include "ReadRec.c"
#include "WriteRec.c"
#include "Compare.c"
#include "InitializeDbf.c"
#include "decipher.c"
#include "Help.c"
#include "Exit.c"
#include "Create.c"
#include "Open.c"
#include "Close.c"
#include "Use.c"
#include "Insert.c"
#include "Delete.c"
#include "Select.c"
#include "Update.c"
#include "Seek.c"

main()
{
	DBF dbf[MAX_OPENED_COUNT];/*存放已打开的表信息，即DBF结构*/
	DBF * cur_dbf;/*当前表指针*/
	DBF * tempDbf = (DBF *)malloc(sizeof(DBF));/*临时表,用于创建表*/
	DBF * dbfPtr = NULL;
	int * opened_dbf_count = (int *)malloc(sizeof(int));/*打开的表数*/
	int i;
	char * commond = (char *)malloc(MAX_COMMOND_COUNT*MAX_COMMOND_LENGTH * sizeof(char));
	char open_style[MAX_OPENED_COUNT];/*记录各个打开的表的打开方式*/
	FILE * opened_fp[MAX_OPENED_COUNT];/*记录表的文件指针*/

	InitializeDbf(tempDbf);
	* opened_dbf_count = 0;
	cur_dbf = tempDbf;

	for (i=0; i<MAX_OPENED_COUNT; i++)
	{
		dbfPtr = &(dbf[i]);
		InitializeDbf(dbfPtr);
		open_style[i] = 'r';
		opened_fp[i] = NULL;
	}
	welcome();
	while (1) {
		printf("RDBSM>");
		switch (decipher(commond)) {
		case ERROR: 
			break;
		case HELP: 
			Help();
			break;
		case EXIT: 
			Exit(dbf);
			break;
		case CREATE: 
			if (Create(tempDbf,commond) != SUCCESS)  
			{
				puts("	创建失败!");
			}
			break;
		case OPEN:
			/*判断已打开的关系数是否超过规定的最大数目*/
			if ((*opened_dbf_count) >= MAX_OPENED_COUNT)
			{	
				puts("	错误，打开的关系已超过MAX_OPENED_COUNT个!!!");
				puts("	请先关闭一个");
				break;
			}
			i = Open(dbf,cur_dbf,commond,open_style);
			if (i >= 0)
			{/*设置当前表指针和打开方式*/
				cur_dbf = &(dbf[i]);
				switch (open_style[i]) {
				case 'r':
					opened_fp[i] = fopen(cur_dbf->dhName,"rb");
					cur_dbf->dhHandle = fileno(opened_fp[i]);
					fseek(opened_fp[i],sizeof(DBF),0);
					break;
				case 'w':
					opened_fp[i] = fopen(cur_dbf->dhName,"rb+");
					cur_dbf->dhHandle = fileno(opened_fp[i]);
					fseek(opened_fp[i],sizeof(DBF),0);
					break;
				default :
					opened_fp[i] = fopen(cur_dbf->dhName,"rb+");
					cur_dbf->dhHandle = fileno(opened_fp[i]);
					fseek(opened_fp[i],sizeof(DBF),0);
					break;
				}
				(*opened_dbf_count)++;
				cur_dbf->dhRecNO = 0;
			}
			else
				puts("	打开失败!!!");
			break;
		case CLOSE:
			i = Close(dbf,commond);
			if (i >= 0)
			{
				opened_fp[i] = NULL;
				open_style[i] = 'r';
				(*opened_dbf_count)--;
				for (i=0; i<MAX_OPENED_COUNT; i++)
					if (dbf[i].dhID != -1)
					{
						cur_dbf = &(dbf[i]);
						printf("	当前关系为%s\n",cur_dbf->dhName);
					}
			}
			else
				puts("	关闭失败!!!");
			break;
		case USE:
			i = Use(dbf, commond);
			if (i != -1)
			{
				cur_dbf = &(dbf[i]);
				printf("	\n使用关系  %s\n",cur_dbf->dhName);
			}
			else
			{
				puts("	未找到该关系，该关系可能还未打开，请用open命令打开");
			}
			break;
		case INSERT:
			if (open_style[cur_dbf->dhID] == 'r')
			{
				puts("	the table is opened with r style, can not be inserted records!!");
				break;
			}
			Insert(cur_dbf,commond,opened_fp);
			break;
		case DELETE:
			if (open_style[cur_dbf->dhID] == 'r')
			{
				puts("	the table is opened with r style, can not delete a record!!");
				break;
			}
			Delete(cur_dbf,commond,opened_fp);
			break;
		case SELECT:
			if (open_style[cur_dbf->dhID] == 'w')
			{
				puts("	the table is opened with w style, can not be select!!");
				break;
			}
			Select(cur_dbf,commond,opened_fp);
			break;
		case UPDATE:
			if (open_style[cur_dbf->dhID] == 'r')
			{
				puts("	the table is opened with r style, can not update a record!!");
				break;
			}
			Update(cur_dbf,commond,opened_fp);
		case SEEK:
			Seek(cur_dbf,commond,opened_fp);
		default:
			break;
		}
	}
}

void welcome()
{
	puts("                          欢迎使用!!!");
	puts("****************************RDBMS*************************************");
	puts("|* Description: 〈数据库〉实验                                       |");
	puts("|* Copyright: Copyright (c) 2006                                     |");
	puts("|* Company: BJTU                                                     |");
	puts("|* @author HuangHan NO.03281159 JK0306                               |");
	puts("|* @version 1.0                                                      |");
	puts("|                                                                    |");
	puts("|                                                                    |");
	puts("|* Enter \"HELP\" to get commonds help                               |");
	puts("**********************************************************************");
}