dbf文件结构

---- 2.Foxpro 中dbf 文件结构---- dbf 文件由文件头和文件记录组成，其中文件头又由数据库说明和字段说明组成。

数据库说明由32 个字节组成，各字节含义见表一：字节含义数据库文件标志有无备注型字段（03H 无）1-3最后一次修改日期4-7文件记录数8-9文件头长度10-11记录长度12-31未用---- 表一---- 字段说明由若干个32 字节组成，每32 字节说明一个字段，各字节含义见表二：字节含义0-10字段名11字段类型12-15该字段在文件首记录中的地址16字段长度17小数位数18-31未用---- 表二---- 文件记录以ASCII 形式存储，每条记录以空格（20H）开头，该空格用来作删除标志用。

---- 3. 建立对应Foxpro 的Oracle 表的SQL 语句---- Foxpro 和Oracle 对应的数据类型的描述见表三：FoxproOracleCharacter(n)char(n) varchar2(n)Number(n,m)number(n-1,m) m< >0number(n,m) m=0Float(n,m)Logicalchar(1)DATEDATE---- 三---- 【注】：---- * 不考虑完整性约束，同时对于TA BLESPACE 及STORA GE 存储参数取缺省值。

---- * 对于数字型字段，n 表示数字的宽度，在Foxpro 中包含小数点位置，而在Oracle 中不包含。

---- * 对于Foxpro logical 型字段类型，由于Oracle 中没有相应的逻辑型变量，故将其转换为字符类型。

---- * 暂且不考虑memo、general、picture 字段的转换。

---- 4. SQL*Loader 控制文件的建立---- 控制文件为SQL*Loader 的核心文件，与Foxpro 字段对应关系为表四：Foxpro 数据类型---- 控制文件语句对应的格式Character(n)CHARNumber(n,m)Float(n,m)DECIMAL EXTERNA L NULLIF < field > = BLANKS （m< >0）INTEGER EXTERNAL NULLIF < field > = BLANKS （m=0）LogicalCHARDATEDATE "YYYYMMDD" NULLIF < field > = BLA NKS---- 四---- 以下是用Borland C++ 5.0 在中文Windows 95 下编制的产生CREATE TA BLE SQL 语句和产生SQL*Loader 数据文件、控制文件的源程序load.cpp。

#include < stdio.h >#include < stdlib.h >#include < iostream.h >#include < fstream.h >#include < string.h >#include < math.h >#define MAX_ROW_LENGTH 1200#define MAX_FIELD_NUMBER 30typedef struct head // dbf头文件结构{ unsigned char mask ;unsigned char date[3] ;unsigned long record_num;unsigned short int head_length;unsigned short int field_length ;} HEA D ;typedef struct field // dbf字段结构{ unsigned char name[11];unsigned char type ;unsigned long add;unsigned char length;unsigned char dec ;} FIELD ;int main(int argc,char **argv){ char buf[MAX_ROW_LENGTH],dbf[40],*sqlload;unsigned int i,field_num;HEAD *dbfhead ;FIELD dbffield[MAX_FIELD_NUM BER];FILE *fout, *fp;if (argc!=2){ cout < < "Usage : load dbfile" < < endl ;return -1;}sqlload = new char(40);dbfhead = new HEA D;strcpy(buf,"");strcpy(dbf,argv[1]);strcat(dbf,".dbf");if ((fp=fopen(dbf,"rb")) == NULL){ cout < < "Cannot open file " < < dbf < < endl;return -1 ;}fseek(fp,0,SEEK_SET);fread(dbfhead,sizeof(HEAD),1,fp); // 读dbf头文件信息field_num = (dbfhead- >head_length-1)/32 -1 ; //字段个数for( i=0; i< field_num; i++){ fseek(fp,32*(i+1),SEEK_SET);fread(&dbffield[i],sizeof(FIELD),1,fp); // 读dbf结构信息}// 产生SQL*Loader 控制文件strcpy(sqlload,argv[1]);strcat(sqlload,".ctl");if ((fout=fopen(sqlload,"w")) == NULL){ cout < < "Cannot open file " < < sqlload < < endl;return -1 ;}fprintf(fout,"LOAD DATA\n");fprintf(fout,"INFILE '%s.txt'\n", argv[1]);fprintf(fout,"INTO TABLE %s (\n", argv[1]);for(i=0;i< field_num;++i){ fprintf(fout, "%11s POSITION(%d:%d)", dbffield[i].name, dbffield[i].add, dbffield[i].add + dbffield[i].length -1 ); switch (dbffield[i].type){ case 'C':case 'L': // 字符型/ 逻辑型fprintf(fout, " CHA R");break ;if (dbffield[i].dec == 0 ) //整数型fprintf(fout, "INTEGER EXTERNAL NULLIF %s = BLANKS", dbffield[i].name);else //实数型fprintf(fout, " DECIMAL EXTERNAL NULLIF %s =BLA NKS", dbffield[i].name );break;case 'D': //日期型fprintf(fout, " DATE 'YYYYMMDD' NULLIF %s = BLANKS", dbffield[i].name);break;default:break;}if(i< field_num -1)fprintf(fout, ",\n") ;}fprintf(fout, ")\n");fclose(fout);// 产生CREATE TA BEL. 的SQL 语句strcpy(sqlload,argv[1]);strcat(sqlload,".sql");if ((fout=fopen(sqlload,"w")) == NULL){ cout < < "Cannot open file " < < sqlload < < endl;return -1 ;}fprintf(fout, "create table %s (\n", argv[1]);for(i=0;i< field_num;i++){ fprintf(fout,"%11s",dbffield[i].name);switch (dbffield[i].type){ case 'C': //字符型fprintf(fout, " CHA R(%d)",dbffield[i].length);break;case 'L': //逻辑型fprintf(fout, " CHA R(1)");break;case 'N': //数字型if (dbffield[i].dec==0)fprintf(fout," NUMBER(%d)", dbffield[i].length) ;elsefprintf(fout, " NUMBER(%d,%d)",dbffield[i].length-1, dbffield[i].dec);case 'D': // 日期型fprintf(fout, " DATE");;break;default:break;}if (i< field_num - 1)fprintf(fout, ",\n");}fprintf(fout, ")\n");fclose(fout);// 产生SQL*Loader数据文件strcpy(sqlload,argv[1]);strcat(sqlload,".txt");if((fout=fopen(sqlload,"w")) == NULL){ cout < < "Cannot open file " < < sqlload < < endl; return -1 ;}fseek(fp,dbfhead- >head_length,SEEK_SET);for(i=0;i< dbfhead- >record_num;i++){ fread(buf,dbfhead- >field_length,1,fp);buf[dbfhead- >field_length] ='\0';fprintf(fout,"%s\n", buf+1); //skip记录首字节(删除标志) }fclose(fout);fclose(fp);delete sqlload;return 0 ;}。