What happens when a deleting a field from a raster dataset?

[JulieWynia]

I am relatively new to GIS and attempted to delete a field from a raster dataset (land cover) in a map package; the result of a serious error message tells me this is not a good thing to do.

I deleted the map package and re-downloaded the map package from the original source; however, the "Open Attribute Table" option for this raster persists in being gray so I cannot open the attribute table to view it.

I don't think I would have affected the original so I am not sure why this problem exists after re-downloading the original map package. Does anyone know what I can do to troubleshoot this issue?

The map package represents demo materials for an online GIS course I am taking. The map includes a relatively small area of a DEM overlaying a "nlcd_2011_land_cover_extracted" raster which had 15 values.

[DanPatterson_Retired]

The exact error message would be useful, I suspect your interpretation of 'not a good thing' might need some elaboration.

Also, why do you need to delete the field in the first place? If you didn't make the map package, then there should be no need to remove anything.

[XanderBakker]

In addition to what Dan Patterson  mentioned, if you would want to delete a Value field of a raster you would actually delete the raster values (which is really not something you would want and that's why it should not be possible). When a raster has no value attribute table, this is normally due to the raster type. If it has decimal (floating) values, the raster will not have an attribute table. It is very likely that the DEM is such a raster.

Dan's question on why you want to delete the field is spot on. If you can clarify that or if you can clarify what you want to achieve, we might be able to provide ways to accomplish it.

[JulieWynia]

Thank you to both Dan and Xander for your replies.

The error message was only on the screen momentarily so I do not know the exact message.

By "not a good thing", the attribute table closed when I deleted the field then, when right clicking on the raster in the TOC, the "Open Attribute Table" was gray (rather than black) thus no longer a viable option.

The map package was provided as demo materials for an online lecture; it showed the results of the lecture demonstration. However, I learn/remember much better if I do something rather than just watch something so I decided to delete the two columns that had been added to the attribute table as a result of the lecture demonstration (so the attribute table looked like the original attribute table in the lecture demo) so that I could follow the process and add them myself. The first column I had deleted had been the result of a join (joining cell values with the land cover type represented by the cell value; there were 15 cell values); this field deletion worked. The second column I attempted to delete was the result of using the field calculator to calculate the total area of each cell value/land cover type; this is when I received the error message and the attribute table closed.

[DanPatterson_Retired]

Julie... If it was a Shape_area field, I might have suggested that it was one of the reserved fields for a featureclass table... but you indicate it was a raster table and that it was an area field resulting from a field calculation which shouldn't be an issue, unless it was a field in the table that was joined to the main table, in which case you can't do that , you can only delete allowed fields in the destination table.  

Having a backup copy would allow you to start again to try to narrow down the issue.  In which case, I would recommend making a new file so that the joins are permanent and you can do whatever you want with the fields that you are allowed to edit without relying on the tenuous/temporary nature of a join

[JulieWynia]

Thank you for responding to my initial inquiry and for following up with further insight so I can better understand how various parts of GIS work (and don't work!).

[DanPatterson_Retired]

Hope you got it worked out Julie