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

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

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