ecust.c

使用C语言实现的数据库管理系统。 支持简单类 SQL语言。

/* Database Manage System */

#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <string.h>

#define MAX_SIZE 50     /*表中所含字段最大长度*/
#define FILE_NAME_LENGTH 15     /*文件名最大长度*/
#define FIELD_NAME_LENGTH 15    /*字段名最大长度*/
#define T_EDIT_LENGTH 15    /* Table Edit 长度*/

typedef struct {
  char sFieldName[FIELD_NAME_LENGTH];    /*列名*/
  char sType[8];            /*列类型*/
  int iSize;                /*列空间大小*/
  char bKey;                /*是否主键*/
  char bNullFlag;           /*是否为空*/
  char bValidFlag;          /*是否有效     */
  } TableMode,*PTableMode;

void main()
{
   TableMode tempTM;     /*临时文件*/
   TableMode FieldSet[MAX_SIZE];
   int bFound;  /* found the table */
   FILE *fp,*tempfp;    /*定义文件指针*/
   int tempi,tempi1,tempiNum,iNum,jNum;  /*iNum is the number of the Field,and jNum is Record */
   char tempc,temps[FILE_NAME_LENGTH],*temps1;
   char recordset[2*MAX_SIZE][FILE_NAME_LENGTH];
   char dbf[FILE_NAME_LENGTH];
   char datf[FILE_NAME_LENGTH];
   char tname[FILE_NAME_LENGTH];
   char temptn[FILE_NAME_LENGTH];   /* 数据库文件名dbf，表名tname */

   char ctemp_edit[15][15],*c;       /*edit语句的中间变量存放数组*/
   char ctable_name[10];
   int size_edit;    /*Size*/
   char key_edit;   /*Key*/
   char null_edit;  /*Null*/
   char valid_edit; /*Valid*/
   char dbfile[15];
   int i=0,j=0,k=0;
   FILE *fp_edit;
   int success=0;
   static int s;    /*size*/
   static char ke,n,v;  /*key,null,valid*/

   int y=0;
   char inssql[15][15];
   int icd=0;
   char again;
   int temp=0;
   char datafile[15];
   int flag=0,sFieldNameFlag=0;
   int t=0;
   int r=0;
   char code[6];
   int login=0;

   strcpy(dbfile,"edit.tmp") ;
   strcpy(datafile,"data.tmp");

   printf("\n---------------SQL For DBMS---------------------\n");

   printf("\n------------Please LogIN The DBMS--------------");

   for(i=0;i<5;i++)
    {
        printf("\nLOG>Password:");
        scanf("%s",code);

        if(strcmp(code,"admin")==0)
        {
            printf("\nLog in Database Manage System Suceess!\n");
            login=1;
            break;
        }
        else
        {
            printf("\nLOG>Wrong Password!\n");
            login=0;
        }
    }

    printf("Please input the datafile name:");
    scanf("%s",datf);

    while(login)
    {
       iNum=0;     /*iNum置0*/

       printf("\nSQL>");
       scanf("%s",ctemp_edit[0]);

        switch(ctemp_edit[0][0])
        {   

        case 'c':     /* 创建新表 */

           if (strcmp(ctemp_edit[0],"create")==0) printf("");
           else { printf("Wrong SQL!\n");break;}

           scanf("%s",ctemp_edit[1]);       /* table */
           scanf("%15s",ctemp_edit[2]);         /*表名*/
           scanf("%s",ctemp_edit[3]);         /*  (  */
           
         do{
           scanf("%15s",ctemp_edit[4]);       /*字段名*/
           scanf("%8s",ctemp_edit[5]);        /*类型*/
           scanf("%d",&size_edit);            /*大小*/

           scanf("%c",&key_edit);
           while(key_edit==' ')
           scanf("%c",&key_edit);         /*主键*/

           scanf("%c",&null_edit);
           while(null_edit==' ')
           scanf("%c",&null_edit);         /*空值*/

           scanf("%c",&valid_edit);
           while(valid_edit==' ')
           scanf("%c",&valid_edit);         /*可视化 一般为y*/
          
           strcpy(tempTM.sFieldName,ctemp_edit[4]);    /*列名*/
           strcpy(tempTM.sType,ctemp_edit[5]);             /* 列类型 */
           tempTM.iSize=size_edit;              /* 大小 */
           tempTM.bKey=key_edit;                /* 主键 */
           tempTM.bNullFlag=null_edit;           /* 值是否为空 */
           tempTM.bValidFlag=valid_edit;         /* 该字段是否有效，这里默认为有效*/

           FieldSet[iNum]=tempTM;           /*将tempTM放入FieldSet数组内*/
                iNum++;                         /*iNum加1*/

           scanf("%c",&again);
           while(again==' ')
           scanf("%c",&again);
          }while(again==',');
           
           scanf("%s",ctemp_edit[11]);        /*  INTO */
           scanf("%s",ctemp_edit[12]);        /*  DataBase_FileName  */



           if (strcmp(ctemp_edit[1],"table")==0) printf("");
           else{ printf(" table ERROR  !!!\n");break;}

         
           if(strcmp(ctemp_edit[3],"(")==0) printf("");
           else { printf(" ( ERROR \n"); break;}

           if(again==')') printf("");
           else { printf(" ) ERROR !!!\n");  break;}

           if(strcmp(ctemp_edit[11],"into")==0) printf("");
           else { printf(" into error!!!\n");  break;}

           if((fp=fopen(ctemp_edit[12],"ab+")) == NULL )
           {
                printf("\nopen or create file error!!!\n" );
                getch();
                exit(1);
           }
           fwrite("~",sizeof(char),1,fp);
           fwrite(ctemp_edit[2],sizeof(char),FILE_NAME_LENGTH,fp);
           fwrite(&iNum,sizeof(int),1,fp);                    /*此表内所含字段结构的数量*/
           fwrite(FieldSet,sizeof(TableMode),iNum,fp);        /*表的字段结构*/
           fclose(fp);                                        /*关闭文件*/
           printf("\nTable Create Successfully!");
           break;


        case 'v': /* 看表 */

           if (strcmp(ctemp_edit[0],"view")==0) printf("");
           else { printf("Wrong SQL!\n");break;}

           scanf("%s",ctemp_edit[1]);      /*读入table*/
           scanf("%s",ctemp_edit[2]);                /*读入表名*/
           scanf("%s",ctemp_edit[3]);        /*读入in*/
           scanf("%s",dbf);                  /*读入文件名*/
                    
           if (strcmp(ctemp_edit[1],"table")==0)
                printf("");
           else{ printf(" table ERROR  !!!\n");break;}
         
           if (strcmp(ctemp_edit[3],"in")==0)
                printf("");
           else{ printf(" in ERROR  !!!\n");break;}
     
       
           if((fp=fopen(dbf,"rb")) == NULL )
           {
              printf("\nFile Not Exist or Bad File!\n" );
              break;
           }

           if(strcmp(ctemp_edit[2],"*")==0)
           {
              printf("\nTables in %s are as following:",dbf);
              while(!feof(fp))
              {
                 tempi=fread(&tempc,sizeof(char),1,fp);
                 if(!tempi)break;
                 if(tempc!='~')
                 {
                     printf("\n%s Database Format NOT correct!",dbf);
                     fclose(fp);
                     exit(1);
                 }

                 fread(tname,sizeof(char),FILE_NAME_LENGTH,fp);
                 fread(&iNum,sizeof(int),1,fp);
                 printf("\n%s",tname);
                 fread(FieldSet,sizeof(TableMode),iNum,fp);
              }
              break;
           }

           else
           {
               while(!feof(fp))
               {                /*输出表所有字段    */
                    bFound=0;
                    tempi=fread(&tempc,sizeof(char),1,fp);
                    if(!tempi)
                        break;
                    fread(temptn,sizeof(char),FILE_NAME_LENGTH,fp);
                    fread(&iNum,sizeof(int),1,fp);
                    fread(FieldSet,sizeof(TableMode),iNum,fp);
                    if(strcmp(ctemp_edit[2],temptn)==0)
                    {
                        printf("\nFound! Table Fields are as following:");
                        printf("\nField Name     Type     Size  Key   Null");
                        printf("\n------------   ------   ----  ----  ---- ");
                        for(tempi=0;tempi<iNum;tempi++)
                            printf("\n%-15s|%-8s|%-5d|%-5c|%-5c|",FieldSet[tempi].sFieldName,FieldSet[tempi].sType,FieldSet[tempi].iSize,FieldSet[tempi].bKey,FieldSet[tempi].bNullFlag);
                        bFound=1;
                        break;  /*break while*/
                    }
                }
            }
            if(!bFound)
                printf("\nNo such a table in %s",dbf);
            fclose(fp);
            break;
           
        case 'e':

           if (strcmp(ctemp_edit[0],"edit")==0){}
           else { printf("Wrong SQL!\n");break;}

           scanf("%s",ctemp_edit[1]);         /*table*/
           scanf("%s",ctemp_edit[2]);         /*表名*/
           scanf("%s",ctemp_edit[3]);         /*  (  */
           scanf("%s",ctemp_edit[4]);       /*字段名*/
           scanf("%s",ctemp_edit[5]);        /*类型*/
           scanf("%d",&size_edit);            /*大小*/

           scanf("%c",&key_edit);
           while(key_edit==' ')
           scanf("%c",&key_edit);         /*主键*/

           scanf("%c",&null_edit);
           while(null_edit==' ')
           scanf("%c",&null_edit);         /*空值*/

           scanf("%c",&valid_edit);
           while(valid_edit==' ')
           scanf("%c",&valid_edit);         /*可视化 一般为y*/

           scanf("%s",ctemp_edit[10]);        /* 判断 ) */
           scanf("%s",ctemp_edit[11]);        /*  IN  */
           scanf("%s",ctemp_edit[12]);        /*  DataBase_FileName  */

           if (strcmp(ctemp_edit[1],"table")==0){}
           else{ printf(" table ERROR  !!!\n");break;}

           if(strcmp(ctemp_edit[3],"(")==0){}
           else { printf(" ( ERROR \n"); break;}

           if(strcmp(ctemp_edit[10],")")==0){}
           else { printf(" ) ERROR !!!\n");  break;}

           if(strcmp(ctemp_edit[11],"in")==0){}
           else { printf(" in ERROR  !!!\n");  break;}

           if((fp=fopen(ctemp_edit[12],"rb")) == NULL )
           {
              printf("\n NOT found DataBase!!!\n" );
              break;
           }

           while(!feof(fp))      /*察看有几个表*/
           {   tempi=fread(&tempc,sizeof(char),1,fp);  /*读第一个字符到tempc中，成功返回1*/
               if(!tempi)break;
               if(tempc!='~')
               {
                   printf("\n%s Database Format NOT correct!",dbf);
                   fclose(fp);
                   exit(1);
               }
               fread(tname,sizeof(char),FILE_NAME_LENGTH,fp);
               fread(&iNum,sizeof(int),1,fp);
               fread(FieldSet,sizeof(TableMode),iNum,fp);
               j++;            /*表的个数*/
           }

           fclose(fp);
           printf("\n");

           if((fp=fopen(ctemp_edit[12],"rb")) == NULL )
           {
              printf("\nNOT found DataBase!!!\n" );
              break;
           }

           rewind(fp);       /*指针到文件头*/

           while(!feof(fp))          /*读表所有字段    */
           {
               s=size_edit;
               ke=key_edit;
               n=null_edit;
               v=valid_edit;

               for(i=0;i<j;i++)   /*j为表的个数*/
               {
                    tempi=fread(&tempc,sizeof(char),1,fp);
                    if(!tempi)break;
                    fread(ctable_name,sizeof(char),FILE_NAME_LENGTH,fp);
                    fread(&iNum,sizeof(int),1,fp);
                    fread(FieldSet,sizeof(TableMode),iNum,fp);

                    if(strcmp(ctemp_edit[2],ctable_name)==0)
                    {    /*比较ctemp_edit[2]和temptn是否相等*/

                        for(tempi=0;tempi<iNum;tempi++)      /*iNum为字段个数*/
                        {

                            if(strcmp(ctemp_edit[4],FieldSet[tempi].sFieldName)==0)
                            {
                                strcpy(tempTM.sFieldName,FieldSet[tempi].sFieldName);    /*字段名*/
                                strcpy(tempTM.sType,ctemp_edit[5]);             /* 列类型 */
                                tempTM.iSize=s;              /* 大小 */
                                tempTM.bKey=ke;                /* 主键 */
                                tempTM.bNullFlag=n;           /* 值是否为空 */
                                tempTM.bValidFlag=v;         /* 该字段是否有效，这里默认为有效*/
                                FieldSet[tempi]=tempTM;
                                success=1;
                            }
                        }
                    }

                         /*下面为重新输入到文件内*/

                    if(k==0)
                    {    if((fp_edit=fopen(dbfile,"wb+"))==NULL)
                        {
                            printf("open or create file error!");
                            getch();
                            exit(1);
                        }
                        fwrite("~",sizeof(char),1,fp_edit);
                        fwrite(ctable_name,sizeof(char),FILE_NAME_LENGTH,fp_edit);    /*输入表名*/
                        fwrite(&iNum,sizeof(int),1,fp_edit);                    /*此表内所含字段结构的数量*/
                        fwrite(FieldSet,sizeof(TableMode),iNum,fp_edit);        /*表的字段结构*/
                        fclose(fp_edit);                                     /*关闭文件*/
                        k++;
                    }
                    else
                    {   if((fp_edit=fopen(dbfile,"ab+"))==NULL)
                        {
                            printf("open or create file error!");
                            getch();
                            exit(1);
                        }
                        fwrite("~",sizeof(char),1,fp_edit);
                        fwrite(ctable_name,sizeof(char),FILE_NAME_LENGTH,fp_edit);    /*输入表名*/
                        fwrite(&iNum,sizeof(int),1,fp_edit);                    /*此表内所含字段结构的数量*/
                        fwrite(FieldSet,sizeof(TableMode),iNum,fp_edit);        /*表的字段结构*/
                        fclose(fp_edit);                                        /*关闭文件*/
                        k++;
                    }
                }

            } /*end of while*/


            fclose(fp);
            j=0;
            k=0;

            if(success==1)
            {
                if(remove(ctemp_edit[12])==0)
                    printf( "");
                if(rename("edit.tmp",ctemp_edit[12])==0)
                    printf( "");
                printf("\n Edit tables successfully  !!!\n");
            }
            else
            {
                printf("Table Name or Feild Name  ERROR   !!!");
            }
            
            success=0;