Neoview SQL Reference Manual (R2.4 SP2)

If all of the expressions in the row-value-constructor are null, the IS NULL predicate is
true. Otherwise, it is false. If none of the expressions in the row-value-constructor are null,
the IS NOT NULL predicate is true. Otherwise, it is false.
Considerations for NULL
Summary of NULL Results
Let rvc be the value of the row-value-constructor. This table summarizes the results of
NULL predicates. The degree of a rvc is the number of values in the rvc.
NOT rvc IS NOT
NULL
NOT rvcIS NULLrvc IS NOT NULLrvc IS NULLExpressions
TRUEFALSEFALSETRUEdegree 1: null
FALSETRUETRUEFALSEdegree 1: not null
TRUEFALSEFALSETRUEdegree>1: all null
TRUETRUEFALSEFALSEdegree>1: some null
FALSETRUETRUEFALSEdegree>1: none null
Note that the rvc IS NOT NULL predicate is not equivalent to NOT rvc IS NULL.
Examples of NULL
• Find all rows with null in the SALARY column:
salary IS NULL
• This predicate evaluates to true if the expression (PRICE + TAX) evaluates to null:
(price + tax) IS NULL
• Find all rows where both FIRST_NAME and SALARY are null:
(first_name, salary) IS NULL
Quantified Comparison Predicates
• “Considerations for ALL, ANY, SOME”
• “Examples of ALL, ANY, SOME”
A quantified comparison predicate compares the values of sequences of expressions to the values
in each row selected by a table subquery. The comparison operation is quantified by the logical
quantifiers ALL, ANY, or SOME.
row-value-constructor comparison-op quantifier table-subquery
row-value-constructor is:
(expression [,expression]...)
| row-subquery
comparison-op is:
= Equal
| <> Not equal
| != Not equal
| < Less than
| > Greater than
| <= Less than or equal to
| >= Greater than or equal to
quantifier is:
ALL | ANY | SOME
284 SQL Language Elements