sql - mysql sum only specific groups of a table -

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is there way sum specific groups of table? example if have 

keys  /  vals     /   1     /   2 b     /   3 b     /   3  c     /   1 c     /   1

and want grouping , c not others such b above:

keys  /  vals     /   3 b     /   3 b     /   3  c     /   2

this seems straightforward stored proc not sure if possible query?

union all non-b part b part:

select keys, sum(vals) tablename keys <> 'b' group keys union select keys, vals tablename keys = 'b'

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