"Vladimir V. Zolotych" wrote:
>Please give me hints how can I use "conditional operators ALL, ANY" in
>WHERE clause.
[This query would have been better directed to the pgsql-sql list.]
>Some examples will be appreciated.
ALL is used to test a value against all of a list of items.
Find the customer whose account has been created the longest:
SELECT id, date_opened
FROM customer
WHERE date_opened IS NOT NULL AND date_opened <= ALL (SELECT date_opened
FROM customer
WHERE date_opened IS NOT NULL);
id | date_opened
-------+-------------
25832 | 1998-01-05
(1 row)
ANY is used to compare against any item of the list; "x = ANY y" is the
same as "x IN y":
SELECT COUNT(*)
FROM customer
WHERE area = ANY (SELECT id
FROM country);
count
-------
216
(1 row)
But note that use of ALL may be very inefficient:
bray=# explain select id,date_opened from customer where date_opened is not
null and date_opened <= all (select date_opened from customer where
date_opened is not null);
NOTICE: QUERY PLAN:
Seq Scan on customer (cost=0.00..240125.47 rows=1144 width=16)
SubPlan
-> Seq Scan on customer (cost=0.00..139.89 rows=1144 width=4)
EXPLAIN
bray=# explain select id,date_opened from customer where date_opened is not
null and date_opened <= (select min(date_opened) from customer);
NOTICE: QUERY PLAN:
Seq Scan on customer (cost=0.00..148.47 rows=381 width=16)
InitPlan
-> Aggregate (cost=139.89..139.89 rows=1 width=4)
-> Seq Scan on customer (cost=0.00..131.31 rows=3431 width=4)
EXPLAIN
--
Oliver Elphick [EMAIL PROTECTED]
Isle of Wight http://www.lfix.co.uk/oliver
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========================================
"And he said unto his disciples, Therefore I say unto
you, Take no thought for your life, what ye shall eat;
neither for the body, what ye shall put on. For life
is more than meat, and the body is more than clothing.
Consider the ravens, for they neither sow nor reap;
they have neither storehouse nor barn; and yet God
feeds them; how much better you are than the birds!
Consider the lilies, how they grow; they toil
not, they spin not; and yet I say unto you, that
Solomon in all his glory was not arrayed like one of
these. If then God so clothe the grass, which is to
day in the field, and tomorrow is cast into the oven;
how much more will he clothe you, O ye of little
faith? And seek not what ye shall eat, or what ye
shall drink, neither be ye of doubtful mind.
But rather seek ye the kingdom of God; and all these
things shall be added unto you."
Luke 12:22-24; 27-29; 31.
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