Is there a better way to indicate “null” values in Excel?

Question

I have an Excel 2007 workbook that contains tables of data that I\'m importing into DataTable objects using ADO.NET.

Through some experimentation, I\'ve

Answer 1

You're hitting the brickwall that many very frustrated users of Excel are experiencing. Unfortunately Excel as a company tool is widespread and seems quite robust, unfortunately because each cell/column/row has a variant data type it makes it a nightmare to handle with other tools such as MySQL, SQL Server, R, RapidMiner, SPSS and the list goes on. It seems that Excel 2007/2010 is not very well supported and even more so when taking 32/64 bit versions into account, which is scandalous in this day and age.

The main problem is that when ACE/Jet access each field in Excel they use a registry setting 'TypeGuessRows' to determine how many rows to use to assess the datatype. The default for "Rows to Scan" is 8 rows. The registry setting 'TypeGuessRows' can specify an integer value from one (1) to sixteen (16) rows, or you can specify zero (0) to scan all existing rows. If you can't change the registry setting (such as in 90% of office environments) it makes life difficult as the rows to guess are limited to the first 8.

For example, without the registry change If the first occurrence of #N/A is within the first 8 rows then IMEX = 1 will return the error as a string "#N/A". If IMEX = 0 then an #N/A will return 'Null'.

If the first occurrence of #N/A is beyond the first 8 rows then both IMEX = 0 & IMEX = 1 both return 'Null' (assuming required data type is numeric).

With the registry change (TypeGuessRows = 0) then all should be fine.

Perhaps there are 4 options:

1. Change the registry setting TypeGuessRows = 0

2. List all possible type variations in the first 8 rows as 'dummy data' (eg memo fields/nchar(max)/ errors #N/A etc)

3. Correct ALL data type anomalies in Excel

4. Don't use Excel - Seriously worth considering!

Edit: Just to put the boot in :) another 2 things that really annoy me are; if the first field on a sheet is blank over the first 8 rows and you can't edit the registry setting then the whole sheet is returned as blank (Many fun conversations telling managers they're fools for merging cells!). Also, if in Excel 2007/2010 you have a department return a sheet with >255 columns/fields then you have huge problems if you need non-contiguous import (eg key in col 1 and data in cols 255+)