create.c

linux 下用c++ 开发的一个小型数据库系统

#include "catalog.h"


const Status RelCatalog::createRel(const string & relation, 
				   const int attrCnt,
				   const attrInfo attrList[])
{
  Status status;
  RelDesc rd;
  AttrDesc ad;
  int     offset = 0 ;  
  int     myi, myj, myn ;

  if (relation.empty() || attrCnt < 1)
    return BADCATPARM;

  if (relation.length() >= sizeof rd.relName)
    return NAMETOOLONG;
  
  for (myi = 0; myi < attrCnt; myi++){
    myn = 0 ;
    for (myj = 0; myj < attrCnt; myj++)
      if (strcmp(attrList[myi].attrName, attrList[myj].attrName) == 0) myn++ ;
    if (myn >= 2) return ATTRXT ;
  }

  if ((status = getInfo( relation, rd)) == OK) return RELEXISTS ;
  
  strncpy( rd.relName, relation.c_str(), relation.length()) ;
  rd.relName[relation.length()] = 0 ;
  rd.attrCnt = attrCnt ;
  if ((status = relCat->addInfo(rd)) != OK) return status ;
 
  int len ;
  for (int i = 0; i < attrCnt; i++){
    strcpy( ad.relName, attrList[i].relName) ;
    len = strlen(attrList[i].relName) ;
    ad.relName[len] = 0 ;
    strcpy( ad.attrName, attrList[i].attrName) ;
    len = strlen(attrList[i].attrName) ;
    ad.attrName[len] = 0 ;
    ad.attrType = attrList[i].attrType ;
    ad.attrLen = attrList[i].attrLen ;
    ad.attrOffset = offset ;
    offset = offset + ad.attrLen ;
    attrCat->addInfo(ad) ;     
  }

  status = createHeapFile(relation) ;
  if (status != OK) return status ;
  
  if (strcmp(rd.relName,"Tmp_Ubase_Result") != 0)
    printf("  Table  %s  Createed!\n", rd.relName) ;
  return OK ;
}