void DBHandle::dropTable(const char *relName) {
/* FileHandle &handle,
AttrType attrType, int attrLength, int attrOffset,
int nullBitOffset, int nullBitMask,
CompOp compOp, void *value) */
std::vector< RID > rids;
char name[MAX_NAME_LENGTH];
strcpy(name, relName);
rm::FileScan attrScan(attrCatalog_, STRING, MAX_NAME_LENGTH, 0, 0, 0, EQ_OP, name);
while (true) {
Record &r = attrScan.next();
if (r.rid.pageNum <= 0)
break;
rids.push_back(r.rid);
}
for (int i = 0; i < rids.size(); i++) {
attrCatalog_.deleteRec(rids[i]);
}
rids.clear();
rm::FileScan relScan(relCatalog_, STRING, MAX_NAME_LENGTH, 0, 0, 0, EQ_OP, name);
while (true) {
Record &r = relScan.next();
if (r.rid.pageNum <= 0)
break;
rids.push_back(r.rid);
}
for (int i = 0; i < rids.size(); i++) {
relCatalog_.deleteRec(rids[i]);
}
rids.clear();
}
RelInfo DBHandle::getRelInfo(const char *relName) {
char name[MAX_NAME_LENGTH];
strcpy(name, relName);
rm::FileScan relScan(relCatalog_, STRING, MAX_NAME_LENGTH, 0, 0, 0, EQ_OP, name);
Record &r = relScan.next();
return *(RelInfo*)(r.getData());
}
void DBHandle::showTables() {
char name[MAX_NAME_LENGTH];
rm::FileScan relScan(relCatalog_, STRING, MAX_NAME_LENGTH, 0, 0, 0, NO_OP, name);
while (true) {
Record &r = relScan.next();
if (r.rid.pageNum <= 0) break;
loadCol(r.getData(), 0, MAX_NAME_LENGTH, STRING, name);
printer << name << endl;
}
}
int DBHandle::findTable(const char *relName) {
char name[MAX_NAME_LENGTH];
strcpy(name, relName);
rm::FileScan relScan(relCatalog_, STRING, MAX_NAME_LENGTH, 0, 0, 0, EQ_OP, name);
while (true) {
Record &r = relScan.next();
if (r.rid.pageNum <= 0) break;
return 1;
}
return 0;
}
/**
* This function scans the relation for tuples
* that match the filter predicate and copy these
* tuples into a relation named result.
*
* @param result
* @param projCnt
* @param projNames[]
* @param attrDesc
* @param op
* @param filter
* @param reclen
* @return: OK on success
* an error code otherwise
**/
const Status ScanSelect(const string & result,
const int projCnt,
const AttrDesc projNames[],
const AttrDesc *attrDesc,
const Operator op,
const char *filter,
const int reclen)
{
Status status;
//used to keep track of how many total tuples are selected
int resultTupCnt = 0;
// open the result table
InsertFileScan resultRel(result, status);
if (status != OK) { return status; }
//initialize pointer a location of size reclen
char outputData[reclen];
//the record to be copied to later
Record outputRec;
outputRec.data = (void *) outputData;
outputRec.length = reclen;
// start scan on outer table
HeapFileScan relScan(attrDesc->relName, status);
if (status != OK) { return status; }
status = relScan.startScan(attrDesc->attrOffset, attrDesc->attrLen, (Datatype) attrDesc->attrType, filter, op);
if (status != OK) { return status; }
// scan outer table
RID relRID;
Record relRec;
while (relScan.scanNext(relRID) == OK) {
status = relScan.getRecord(relRec);
ASSERT(status == OK);
// we have a match, copy data into the output record
int outputOffset = 0;
for (int i = 0; i < projCnt; i++) {
memcpy(outputData + outputOffset, (char *)relRec.data + projNames[i].attrOffset, projNames[i].attrLen);
outputOffset += projNames[i].attrLen;
} // end copy attrs
// add the new record to the output relation
RID outRID;
status = resultRel.insertRecord(outputRec, outRID);
ASSERT(status == OK);
resultTupCnt++;
}
//before returning print out the total number of tuples in this relation
printf("selected %d result tuples \n", resultTupCnt);
return OK;
}
