Method Next

backend/iter.go:112–185

Next retrieves the next row. It will return io.EOF if it's the last row.

(ctx *sql.Context)

// Next retrieves the next row. It will return io.EOF if it's the last row.
func (iter *SQLRowIter) Next(ctx *sql.Context) (sql.Row, error) {
	if !iter.rows.Next() {
		if err := iter.rows.Err(); err != nil {
			return nil, err
		}
		return nil, io.EOF
	}

	// Scan the values into the buffer
	if err := iter.rows.Scan(iter.pointers[:len(iter.columns)]...); err != nil {
		return nil, err
	}

	// Process decimal values
	for _, idx := range iter.decimals {
		switch v := iter.buffer[idx].(type) {
		case duckdb.Decimal:
			iter.buffer[idx] = decimal.NewFromBigInt(v.Value, -int32(v.Scale))
		case string:
			iter.buffer[idx], _ = decimal.NewFromString(v)
		}
	}

	// Process interval values
	for _, idx := range iter.intervals {
		t := types.TimespanType_{}
		switch v := iter.buffer[idx].(type) {
		case duckdb.Interval:
			iter.buffer[idx] = t.MicrosecondsToTimespan(v.Micros + int64(v.Days)*24*60*60*1000000) // ignore the month part, which does not appear in MySQL
		}
	}

	// Process type conversions
	for _, targetType := range iter.conversions {
		idx := targetType.idx
		rawValue := iter.buffer[idx]
		if targetType.kind == reflect.Float64 {
			switch v := rawValue.(type) {
			case *big.Int:
				iter.buffer[idx], _ = v.Float64()
			}
		}
		if targetType.kind == reflect.Int64 {
			switch v := rawValue.(type) {
			case float64:
				iter.buffer[idx] = int64(v)
			case float32:
				iter.buffer[idx] = int64(v)
			case *big.Int:
				iter.buffer[idx] = v.Int64()
			}
		}
	}

	// Prune or fill the values to match the schema
	width := len(iter.schema) // the desired width
	if width == 0 {
		width = len(iter.columns)