insert.c

一个c语言开发的小型的dbms系统

#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include <malloc.h>
#include "struct.h"
#include <time.h>
void insert(struct tab_dic_type table,struct col_dic_type *table_fields,int ft_num,struct col_dic_type *fields,int f_num,char values[10][40])
{char *data,*data1,*data_addr;
 int  *int_data,*int_data1,*int_data_addr;
 //char test_data[20];
 int offset[10];
 int offset1;//数据块偏移地址
 int i,j,data_size;
 int current_block,last_block;
 struct data_head head_data,head_data_temp;
 struct tab_dic_type free_block;
 FILE *data_fp,*tab_fp;
//test
//  get_last(table);

 offset[0]=0;
 data_size=0;

 data_size=table.row_len;
 //开辟数据块空间
 data=(char *)malloc(data_size);
 data_addr=(char *)malloc(data_size);

 if((data_fp=fopen("DATABASE","rb+"))==NULL)
   {printf("cann't open file DATABASE\n");
    exit(0);
   }/*打开数据文件*/

 if((tab_fp=fopen("TABLE","rb+"))==NULL)
   {printf("cann't open file TABLE\n");
    exit(0);
   }/*打开表字典文件*/ 

 fread(&free_block,sizeof(struct tab_dic_type),1,tab_fp);
 
 //选择表的空闲数据块
 current_block=table.first_free_block;
 fseek(data_fp,table.first_free_block*1024,0);
 fread(&head_data,sizeof(struct data_head),1,data_fp);
 while (head_data.next_block!=-1)
	{current_block=head_data.next_block;
	 fseek(data_fp,current_block*1024,0);
	 fread(&head_data,sizeof(struct data_head),1,data_fp);
	}

 fseek(data_fp,head_data.next_free_addr,0);
 fseek(tab_fp,table.tab_id*sizeof(struct tab_dic_type),0);
 
 for (i=1;i<f_num;i++)
     offset[i]=offset[i-1]+table_fields[i-1].col_length+1;

 //读取下一空闲块地址并恢复文件指针到原位
 fread(data_addr,data_size,1,data_fp);
 int_data_addr=data_addr;
 fseek(data_fp,head_data.next_free_addr,0);

 for(i=0;i<data_size;i++)
	 data[i]='\0';
 for(i=0;i<f_num;i++)
 {j=fields[i].col_id-100*fields[i].tab_id;
  if (fields[i].col_type==0)
  {  int_data=&data[offset[j]];
     *int_data=atoi(&values[i]);
  }
  else
     strcpy(&data[offset[j]],values[i]);
 }
 //strcpy(&test_data,&data[21]);
 table.row_num=table.row_num+1;
  
 //修改数据块头信息
//if (*int_data_addr<=(table.first_free_block+1)*1024)
  if (*int_data_addr<(current_block+1)*1024)
	{head_data.next_free_addr=*int_data_addr;
 fflush(data_fp);
	 if (fwrite(data,data_size,1,data_fp)!=1)
        printf("_data file write error!\n");
	 fseek(data_fp,current_block*1024,0);
	 if (fwrite(&head_data,sizeof(struct data_head),1,data_fp)!=1)
       printf("_data file(data_head) write error!\n");
	}
 else
 {head_data.next_block=free_block.first_free_block;//块头信息更新
  fseek(data_fp,current_block*1024,0);
  if (fwrite(&head_data,sizeof(struct data_head),1,data_fp)!=1)
      printf("_data file(data_head) write error!\n");
  //表空间扩展处理
 last_block=current_block;
 current_block=free_block.first_free_block;

 //读取空闲块块头信息
    fseek(data_fp,free_block.first_free_block*1024,0);
fflush(data_fp);
    fread(&head_data_temp,sizeof(struct data_head),1,data_fp);
  if (head_data_temp.last_block==-2)
	free_block.first_free_block=head_data_temp.next_block;
  else
	free_block.first_free_block=free_block.first_free_block+1;//第一空闲块更新
 
 fseek(tab_fp,0,0);
 fflush(data_fp);
 if (fwrite(&free_block,sizeof(struct tab_dic_type),1,tab_fp)!=1)
      printf("_tab_dic file(free_block) write error!\n");
 //填写数据头信息
 head_data.next_block=-1;
 head_data.last_block=last_block;
 head_data.next_free_addr=current_block*1024+24+data_size;
 fseek(data_fp,current_block*1024,0);
 if (fwrite(&head_data,sizeof(struct data_head),1,data_fp)!=1)
     printf("_data file(data_head) write error!\n");
 fseek(data_fp,current_block*1024+24,0);
 offset1=ftell(data_fp);
 while (offset1<=(free_block.first_free_block*1024-1))
		{data1=(char *)malloc(table.row_len);
		 int_data1=data1;
		 *int_data1=offset1+table.row_len;
		 offset1=offset1+table.row_len;
		 if (fwrite(data1,table.row_len,1,data_fp)!=1)
			printf("_data file write error!\n");
		 free(data1);
		}
 fseek(data_fp,current_block*1024+24,0);
 if (fwrite(data,data_size,1,data_fp)!=1)
        printf("_data file write error!\n"); 
 }
 fseek(tab_fp,table.tab_id*sizeof(struct tab_dic_type),0);
 if (fwrite(&table,sizeof(struct tab_dic_type),1,tab_fp)!=1)
       printf("_tab_dic file write error!\n");
 fclose(tab_fp);
 //fclose(col_fp);
 fclose(data_fp);
 free(data_addr);
 free(data);
 //free(data1);
 // if( fclose( data_fp ) )
  //    printf( "The file 'data' was not closed\n" );

}