Method getTupleDesc

src/java/simpledb/execution/SeqScan.java:112–124

Returns the TupleDesc with field names from the underlying HeapFile, prefixed with the tableAlias string from the constructor. This prefix becomes useful when joining tables containing a field(s) with the same name. The alias and name should be separated with a "." character (e.g., "alias.fieldName

()

     *         prefixed with the tableAlias string from the constructor.
     */
    public TupleDesc getTupleDesc() {
        // some code goes here
        TupleDesc tupleDesc = Database.getCatalog().getDatabaseFile(this.tableId).getTupleDesc();
        int itemLen = tupleDesc.getItemLength();
        Type[] types = new Type[itemLen];
        String[] fieldNames = new String[itemLen];
        for(int i=0;i<itemLen;i++){
            types[i] = tupleDesc.getFieldType(i);
            fieldNames[i] = this.tableAlias +"."+ tupleDesc.getFieldName(i);
        }

        return new TupleDesc(types,fieldNames);
    }

    public boolean hasNext() throws TransactionAbortedException, DbException {
        // some code goes here