>>'true' and 'false' are literal values for bit but it only works when comparing to bit
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>The real shortcoming of bit values in TSQL is that you can't use them in expressions unless a part of comparison, i.e.
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when a and b then 100 else when a and not b then 50 ...

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>doesn't work, a and b, bit fields, are not recognised as boolean values in a logical expression, you have to put it as
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when a=1 and b=1 then 100 else when a=1 and  b=0 then 50 ...

Yep, Unfortunately T-SQL doesn't have logical data type