We can not only use the attribute tables of layers, but we can also extend, decrease, or modify them. These are very useful functions for maintaining a layer. For example, as data often comes in a general format with a lot of obsolete attributes, which is practically useless for our analysis, we can get rid of it in a matter of clicks. The size of the attribute table always has an impact on performance; therefore, it is beneficial to not store superfluous data.
In the first example, let's delete some values from our administrative boundaries layer. If we inspect its attribute table, we can see some unnecessary columns. In my table, ID_0
and CCN_1
have constant values, which have absolutely no meaning to me. The CCA_1
and NL_NAME_1
columns are filled with null values, while VARNAME_1
is scarcely filled, therefore, I cannot use them. Let's pick every unnecessary column and remember their names. In the attribute table's toolbar, we can see some tools...