Is there any equivalent to Postgresql EVERY aggregate function on other RDBMS?

问题

Documentation for EVERY aggregate:

every(expression) : true if all input values are true, otherwise false

http://www.postgresql.org/docs/9.1/static/functions-aggregate.html

EVERY is semantically equivalent to COUNT(conditionIsTrue) = COUNT(*)

select person_id, 

    every(visited_site = 'http://stackoverflow.com') as visited_same_site_forever,

    count(case when visited_site = 'http://stackoverflow.com' then '^_^' end) 
    = count(*) as visited_same_site_forever2

from z
group by person_id
order by person_id

Output:

 person_id | visited_same_site_forever | visited_same_site_forever2 
-----------+---------------------------+----------------------------
        88 | f                         | f
     55327 | t                         | t
    256196 | f                         | f

Data source:

create table z(person_id int, visited_site varchar(100), datetime_visited timestamp);

insert into z values
(55327,'http://stackoverflow.com','Jan 1, 2010'),
(55327,'http://stackoverflow.com','Feb 14, 2012'),
(55327,'http://stackoverflow.com','May 1, 2012'),
(256196,'http://stackoverflow.com','February 1, 2012'),
(256196,'http://stackoverflow.com','February 2, 2012'),
(256196,'http://slashdot.org','May 2, 2012'),
(88,'http://theregister.co.uk','April 1, 2012'),
(88,'http://slashdot.org','April 2, 2012');

回答1:

Emulating `EVERY()` with `CASE` and `SUM()`

In fact, this article describes how EVERY() can be emulated via CASE and SUM(). The following two statements are equivalent:

SELECT EVERY(id < 10)
FROM book

SELECT CASE SUM(CASE WHEN id < 10 THEN 0 ELSE 1 END) 
         WHEN 0 THEN 1 
         ELSE 0 
       END
FROM book;

The same is true for the EVERY() window function:

SELECT 
  book.*, 
  EVERY(title LIKE '%a') OVER (PARTITION BY author_id)
FROM book

SELECT
  book.*,
  CASE SUM(CASE WHEN title LIKE '%a' THEN 0 ELSE 1 END)
       OVER(PARTITION BY author_id)
    WHEN 0 THEN 1 
    ELSE 0
  END
FROM book;

SQL Standard

The SQL:2008 standard mentions the EVERY aggregate function:

10.9 <aggregate function>

[...]

<aggregate function> ::=
  COUNT <left paren> <asterisk> <right paren> [ <filter clause> ]
  | <general set function> [ <filter clause> ]
  | <binary set function> [ <filter clause> ]
  | <ordered set function> [ <filter clause> ]

<general set function> ::=
  <set function type> <left paren> [ <set quantifier> ]
  <value expression> <right paren>

<set function type> ::=
  <computational operation>

<computational operation> ::=
  AVG
  | MAX
  | MIN
  | SUM
  | EVERY
  | [...]

But "advanced" SQL standard features are not often implemented by databases. Oracle 11g for instance, doesn't support it, neither does SQL Server 2012.

With HSQLDB, however, you may be more lucky. HSQLDB 2.x is very standards-compliant, also MySQL knows the BIT_AND() aggregate function, which is a non-standard alias to EVERY(), also supported by Postgres.

Note, some databases allow for writing user-defined aggregate functions, so you may as well implement EVERY() yourself.

来源：https://stackoverflow.com/questions/10407354/is-there-any-equivalent-to-postgresql-every-aggregate-function-on-other-rdbms

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