Dealing with NULL values in geodatabase using GDAL commands?

I have a geodatabase and I’d like to return a value for NULL. (When I look at my raster layer, there are a lot of zeroes which I am assuming is because of the NULL values)

Is there a way to use the hstore_get_value() to map NULL to some value?

I already am using the hstore_get_value() in the gdal_rasterize command so this way would be ideal.

If this is not possible, then how can I update the database so that null is replaced with some value. I am trying to run the following command:

./ogrinfo geodatabasename.gdb -sql "update tablename set columnname='No value' where columnname is null"

But I get the following error:

ERROR 1: SQL Expression Parsing Error: syntax error, unexpected
identifier, expecting SELECT or ‘(‘. Occured around :

Not sure if this ./ogrinfo only accepts SELECT statements, but is there anyway of updating the table using gdal commands? If not, how can I update the table?