help.C

#include <sys/types.h>
#include <functional>
#include <string.h>
#include <stdio.h>
using namespace std;

#include "error.h"
#include "utility.h"
#include "catalog.h"

// define if debug output wanted


//
// Retrieves and prints information from the catalogs about the for the
// user. If no relation is given (relation is NULL), then it lists all
// the relations in the database, along with the width in bytes of the
// relation, the number of attributes in the relation, and the number of
// attributes that are indexed.  If a relation is given, then it lists
// all of the attributes of the relation, as well as its type, length,
// and offset, whether it's indexed or not, and its index number.
//
// Returns:
// 	OK on success
// 	error code otherwise
//

const Status RelCatalog::help(const string & relation)
{
  Status status;
  RelDesc rd;
  AttrDesc *attrs;
  int attrCnt;

  if (relation.empty())
    return UT_Print(RELCATNAME);

  // get relation data

  if ((status = getInfo(relation, rd)) != OK)
    return status;

  // get attribute data

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

  // print relation information

  cout << "Relation name: " << rd.relName << " ("
       << rd.attrCnt << " attributes)" << endl;

  printf("%16.16s   Off   T   Len   I\n\n",  "Attribute name");
  for(int i = 0; i < attrCnt; i++) {
    Datatype t = (Datatype)attrs[i].attrType;
    printf("%16.16s   %3d   %c   %3d\n", attrs[i].attrName,
	   attrs[i].attrOffset,
	   (t == INTEGER ? 'i' : (t == FLOAT ? 'f' : 's')),
	   attrs[i].attrLen);
  }

  free(attrs);

  return OK;
}