sql - database data structure using powers of two -


i'm designing data structure , wanted know if missing doing way.

lets have column day of type int.

1  : monday 2  : tuesday 4  : wednesday 8  : thursday 16 : friday 32 : saturday 64 : sunday

if wanted store monday , friday input 17 day column. if wanted store tuesday , wednesday enter 6 etc.

is valid way of storing data. how query if wanted select record contained saturday , variation of days, or saturday not wednesday. possible? fast?

what concept called?

some people may tell code 'smell' because represents denormalisation, think valid use of bit-mask field:

-- contains saturday , other combination of days select * table (daybitcolumn & 32) = 32  -- contains saturday , other combination of days, except wednesday select * table (daybitcolumn & 32) = 32 , (daybitcolumn & 4) = 0

edit: pointed out @andriy m, can written more succinctly as:

select * table (daybitcolumn & 36) = 32

['&' bitwise and]


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