Broken NullDecimal

[xhit]

I modified the code for documentation (#38 (comment)) for tried with driver.NullDecimal instead driver.Decimal:

	db, err := sql.Open("hdb", connstring)
	if err != nil {
		log.Fatal(err)
	}
	defer db.Close()

	query := "select decimal_column from test"

	rows, err := db.Query(query)
	if err != nil {
		log.Fatal(err)
	}

	defer rows.Close()

	//The 1 is the columns len returned in query
	recordPointers := make([]interface{}, 1)

	//For Decimal Column
	var t driver.NullDecimal
	recordPointers[0] = &t

	for rows.Next() {

		// Scan the result into the column pointers...
		if err := rows.Scan(recordPointers...); err != nil {
			log.Fatal(err)
		}

		for _, v := range recordPointers {
			switch x := v.(type) {

			case *driver.NullDecimal:
				if x.Valid {
					d := (*big.Rat)(x.Decimal)
					log.Print(d.FloatString(6))
				} else {
					log.Print("NULL")
				}

			default:
				log.Print("is not Decimal")
			}
		}
	}

When decimal_column is NULL the code return NULL but when is not null return the error:
sql: Scan error on column index 0, name "decimal_column": invalid decimal value <nil>

I expect the decimal value.

If driver.Decimal is used then I got the value but when column is NULL then the same error is returned.

[stfnmllr]

driver.NullDecimal needs to be 'instantiated' with non-nil Decimal attribute, like
var t = driver.NullDecimal{Decimal: new(driver.Decimal)}
The uninitialized Decimal attribute causes the error message you get after scan.
It's arguable why the Decimal isn't created automatically, but full allocation control should be with the user of the client lib - no lib internal magic.

[xhit]

Perfect. Thanks!