Quantified comparison predicate
The quantified comparison predicate is used to compare a value
with the result of a query.
Syntax
<quantified
comparison predicate> ::=
<value
expression> <comparison operator> ( ALL |
SOME | ANY ) '(' <query specification>
')'.
|
The <query specification> must have the a result of one
column. The data type of the <value
expression> must be comparable to the type of that
column.
If ALL is specified, the result of the <quantified comparison predicate> is:
-
true, if the result of
the <query specification> is empty or
if the implied <comparison predicate>
between the <value expression> and all
the rows of the result of the <query
specification> evaluates to true.
-
false, if the implied
<comparison predicate> between the
<value expression> and at least one row
of the result of the <query
specification> evaluates to false.
-
unknown,
else.
If SOME or ANY is specified, the
result of the <quantified comparison
predicate> is:
-
true, if the implied
<comparison predicate> between the
<value expression> and at least one row
of the result of the <query
specification> evaluates to true.
-
false, if the result
of the <query specification> is empty
or if the implied <comparison
predicate> between the <value
expression> and all the rows of the result of the <query specification> evaluates to false.
-
unknown, else.
Example
SELECT * FROM a WHERE c > ALL (
SELECT c FROM b )
|
The Quantified
Comparison. This
SELECT yields all rows from table a where
the column a.c has a
value that is greater than all values of column b.cin
table b.
More Information
Value
expressions
Query
Specification