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In Transact-SQL, the functions return zero or one rather than Boolean values True and False. IsArray(name) This function determines whether the variable name passed as its argument is an array. Uninitialized arrays will, note, return False from this function in Visual Basic .NET. [7]
Access represents TRUE as −1, while it is 1 in SQL Server; Access does not support the Null tri-state, supported by SQL Server; PostgreSQL has a distinct BOOLEAN type as in the standard, [21] which allows predicates to be stored directly into a BOOLEAN column, and allows using a BOOLEAN column directly as a predicate in a WHERE clause.
In this example a new strong type string named "someString" is created (using Type inference) and the iif function will fill it depending on the outcome of the boolean expression. SQL Server 2012 and newer implements the IIF() function ( Transact-SQL ):
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.
The condition is evaluated true or false as a Boolean expression. On the basis of the evaluation of the Boolean condition, the entire expression returns value_if_true if condition is true, but value_if_false otherwise. Usually the two sub-expressions value_if_true and value_if_false must have the same type, which determines the type of the ...
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 ...
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.
The SQL:1999 standard calls for a Boolean type, [1] but many commercial SQL servers (Oracle Database, IBM Db2) do not support it as a column type, variable type or allow it in the results set. Microsoft SQL Server is one of the few database systems that properly supports BOOLEAN values using its "BIT" data type [citation needed]. Every 1–8 ...