select.c

linux 下用c++ 开发的一个小型数据库系统

#include "catalog.h"
#include "query.h"


// forward declaration
const Status ScanSelect(const string & result, 
			const int projCnt, 
			const AttrDesc projNames[],
			const AttrDesc *attrDesc, 
			const Operator op, 
			const char *filter,
			const int reclen);

/*
 * Selects records from the specified relation.
 *
 * Returns:
 * 	OK on success
 * 	an error code otherwise
 */

const Status QU_Select(const string & result, 
		       const int projCnt, 
		       const attrInfo projNames[],
		       const attrInfo *attr, 
		       const Operator op, 
		       const char *attrValue)
{
   // Qu_Select sets up things and then calls ScanSelect to do the actual work
   // cout << "Doing QU_Select " << endl;
   InsertFileScan	*ifs = NULL ;
   HeapFileScan		*hfs = NULL ;
   AttrDesc		ads ;
   RelDesc		rds ;
   AttrDesc		*attrs ;
   Record		rec ;
   RID			rid, rid1 ;
   string 		astr, bstr ;
   int			intval ;
   float		flval ;
   char			*mydata ;
   int			i, n, t, len, attrCnt ;
   Status		status ;
   
   if ((status = relCat->getInfo( result.c_str(), rds)) != OK) return status ;
   bstr.append(projNames[0].relName) ;
   if ((status = relCat->getInfo( bstr.c_str(), rds)) != OK) return status ;
   
   len = 0 ;   
   astr.append("projName") ;
   for( i = 0; i < projCnt; i++){
     astr.erase(1) ;
     n = strlen(projNames[i].attrName) ;
     astr.replace( 0, n, projNames[i].attrName) ;
     if((status = attrCat->getInfo( bstr, astr, ads)) != OK)
       return status ;
     len = len + ads.attrLen ;
   }
   
   if (attr == NULL){
     ifs =new InsertFileScan( result, status) ;
       if(status != OK) return status ;

     hfs =new HeapFileScan( bstr, status) ;
       if(status != OK) return status ;

     status =attrCat->getRelInfo( bstr, attrCnt, attrs) ;
       if (status != OK) return status ;

     hfs->startScan( 0, 0, (Datatype)attrs[0].attrType, NULL, EQ ) ;

     mydata = new char[len] ;
     char *tmpattr = NULL ;
     int tempi, tempf ;
     while(hfs->scanNext(rid) != FILEEOF){
       hfs->getRecord(rec) ;

       t = 0 ;
       for( i = 0; i < len; i++) mydata[i] = 0 ;

         for (i = 0; i < attrCnt; i++){
           tmpattr = (char *)rec.data + attrs[i].attrOffset;
           switch(attrs[i].attrType) {
             case INTEGER:
               memcpy(&tempi, tmpattr, sizeof(int));
               break;
             case FLOAT:
               memcpy(&tempf, tmpattr, sizeof(float));
               break;
           }
           for (n = 0; n < projCnt; n++){
             if (strcmp(attrs[i].attrName, projNames[n].attrName) == 0){
               if (attrs[i].attrType == INTEGER){
                 memcpy( mydata + t, &tempi, sizeof(int)) ;
                 t = t + sizeof(int) ;
               }
               if (attrs[i].attrType == FLOAT){
                 memcpy( mydata + t, &tempf, sizeof(float)) ;
		 t = t + sizeof(float) ;
               }
               if (attrs[i].attrType == STRING){
                 memcpy( mydata + t, tmpattr, attrs[i].attrLen) ;
                 t = t + attrs[i].attrLen ;
               }
             }
           }
         }

      rec.data = mydata ;
      rec.length = len ;
      ifs->insertRecord( rec, rid1) ;
    }

     delete [] attrs ;
     delete [] mydata ;
     delete hfs ;
     delete ifs ;
     return OK ;

  }
   
   cout<<"where"<<endl ;
   astr.append("attr") ;
   astr.erase(1) ;
   n = strlen(attr[0].attrName) ;
   astr.replace( 0, n, attr[0].attrName) ;
   
   if ((status = attrCat->getInfo( bstr, astr, ads)) != OK) return status ;
   
   ifs =new InsertFileScan( result, status) ;
   if(status != OK) return status ;
   
   hfs =new HeapFileScan( bstr, status) ;
   if(status != OK) return status ;   

   status =attrCat->getRelInfo( bstr, attrCnt, attrs) ;
   if (status != OK) return status ;

    if (ads.attrType == INTEGER){
      intval = atoi(attrValue) ;
      hfs->startScan( ads.attrOffset, ads.attrLen,
                      (Datatype)ads.attrType, (char *)&intval, op) ;
    }

    if (ads.attrType == FLOAT){
      flval =(float)atof(attrValue) ;
      hfs->startScan( ads.attrOffset, ads.attrLen,
                      (Datatype)ads.attrType, (char *)&flval, op) ;
    }

    if (ads.attrType == STRING){
       hfs->startScan( ads.attrOffset, ads.attrLen,
                       (Datatype)ads.attrType, attrValue, op) ;
    }
   
   mydata = new char[len] ;
   while(hfs->scanNext(rid) != FILEEOF){
     hfs->getRecord(rec) ;

     t = 0 ;
     for( i = 0; i < len; i++) mydata[i] = 0 ;

      for (i = 0; i < attrCnt; i++){
         for (n = 0; n < projCnt; n++){
          if (strcmp(attrs[i].attrName, projNames[n].attrName) == 0){
            memcpy( mydata + t,(char *)rec.data + attrs[i].attrOffset,
                    attrs[i].attrLen) ;
            t = t + attrs[i].attrLen ; 
          }
        }
      }
     
      rec.data = mydata ;
      rec.length = len ;
      ifs->insertRecord( rec, rid1) ;
   }      
   
   delete [] attrs ;
   delete [] mydata ;
   delete hfs ;
   delete ifs ;
   return OK ; 
}


const Status ScanSelect(const string & result, 
			const int projCnt, 
			const AttrDesc projNames[],
			const AttrDesc *attrDesc, 
			const Operator op, 
			const char *filter,
			const int reclen)
{
   // cout << "Doing HeapFileScan Selection using ScanSelect()" << endl;
   
  return OK ;
}