>>>They were introduced in SQL-99 - you probably blocked that memory, as this was the SQL that added official support for boolean data type - sticking it to Oracle and DB2 ;-))
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>>SQL Server doesn't have boolean data type either
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>UPDATE
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>In practise it does not matter. The bit datatype can hold only three vaues. 0, 1 and NULL, just like the boolean datatype.

In practice it's equally useless, as you can't do anything with it - no operators work with those values. You can't say "if table1.bitfld1 OR table2.bitfld2" or any such thing - the stored values or variables with such values can't be used in boolean expressions, only in comparisons. Damn, even the 5K basic interpreter on ZX Spectrum, 36 years ago, was able to do "if x and y then".