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Primitive Data Types TutorialFunctions isNull and IfNullDatabase and map usage may result in NULL string value. For example, the reading of a map value corresponding to a non-existing key results in NULL value. Function isNull(s), of type ( String -> Bool ), tests if the string s is NULL or not. Function ifNull(s,p), of type ( String * String -> Bool ), returns s if it is not NULL, and p if s is NULL.
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© 2006 Saša Malkov | |||||||||||||||