Consolidate List of what datatypes of a column can be altered - from and to - topic by tdreturn

I am trying to get a list/mapping of the data types I can change using an alter command and to what.    For example, I am trying to alter an integer column to a bigint and is it not letting me do it. Would love to know if there is a consolidate list somewhere, where I can see what alters are allowed per datatype.    Thanks