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  2. Boolean data type - Wikipedia

    en.wikipedia.org/wiki/Boolean_data_type

    The SQL:1999 standard introduced a BOOLEAN data type as an optional feature (T031). When restricted by a NOT NULL constraint, a SQL BOOLEAN behaves like Booleans in other languages, which can store only TRUE and FALSE values. However, if it is nullable, which is the default like all other SQL data types, it can have the special null value also.

  3. SQL syntax - Wikipedia

    en.wikipedia.org/wiki/SQL_syntax

    Predicates, which specify conditions that can be evaluated to SQL three-valued logic (3VL) (true/false/unknown) or Boolean truth values and are used to limit the effects of statements and queries, or to change program flow. Queries, which retrieve the data based on specific criteria. This is an important element of SQL.

  4. Three-valued logic - Wikipedia

    en.wikipedia.org/wiki/Three-valued_logic

    in the skew binary number system, only the least-significant non-zero digit can have a value of 2, and the remaining digits have a value of 0 or 1; 1 for true, 2 for false, and 0 for unknown, unknowable/undecidable, irrelevant, or both; [16] 0 for false, 1 for true, and a third non-integer "maybe" symbol such as ?, #, ⁠ 1 / 2 ⁠, [17] or xy.

  5. Null (SQL) - Wikipedia

    en.wikipedia.org/wiki/Null_(SQL)

    E. F. Codd mentioned nulls as a method of representing missing data in the relational model in a 1975 paper in the FDT Bulletin of ACM-SIGMOD.Codd's paper that is most commonly cited with the semantics of Null (as adopted in SQL) is his 1979 paper in the ACM Transactions on Database Systems, in which he also introduced his Relational Model/Tasmania, although much of the other proposals from ...

  6. Truth table - Wikipedia

    en.wikipedia.org/wiki/Truth_table

    A truth table is a mathematical table used in logic—specifically in connection with Boolean algebra, Boolean functions, and propositional calculus—which sets out the functional values of logical expressions on each of their functional arguments, that is, for each combination of values taken by their logical variables. [1]

  7. Boolean function - Wikipedia

    en.wikipedia.org/wiki/Boolean_function

    In mathematics, a Boolean function is a function whose arguments and result assume values from a two-element set (usually {true, false}, {0,1} or {-1,1}). [ 1 ] [ 2 ] Alternative names are switching function , used especially in older computer science literature, [ 3 ] [ 4 ] and truth function (or logical function) , used in logic .

  8. Truth value - Wikipedia

    en.wikipedia.org/wiki/Truth_value

    In C, the number 0 or 0.0 is false, and all other values are treated as true. In JavaScript, the empty string (""), null, undefined, NaN, +0, −0 and false [3] are sometimes called falsy (of which the complement is truthy) to distinguish between strictly type-checked and coerced Booleans (see also: JavaScript syntax#Type conversion). [4]

  9. Boolean-valued function - Wikipedia

    en.wikipedia.org/wiki/Boolean-valued_function

    A Boolean-valued function (sometimes called a predicate or a proposition) is a function of the type f : X → B, where X is an arbitrary set and where B is a Boolean domain, i.e. a generic two-element set, (for example B = {0, 1}), whose elements are interpreted as logical values, for example, 0 = false and 1 = true, i.e., a single bit of information.