MySQL: How to bulk SELECT rows with multiple pairs in WHERE clause

问题

Let's say I have a table, email_phone_notes that looks like this:

+-----------------------+--------------+------+-----+---------+-------+
| Field                 | Type         | Null | Key | Default | Extra |
+-----------------------+--------------+------+-----+---------+-------+
| email                 | varchar      | NO   | PRI | NULL    |       |
| phone                 | varchar      | NO   | PRI | NULL    |       |
| notes                 | text         | NO   |     | 0       |       |
+-----------------------+--------------+------+-----+---------+-------+

So, each email/phone combination is unique, but you could have several email addresses with different phone numbers and vice versa. This is a little contrived but it mirrors my scenario.

I'd like to do a query like this:

SELECT * FROM email_phone_notes  WHERE email = 'foo@bar.com' AND phone = '555-1212';

But, I'd like to do multiple pairs at once so I don't have to make several SELECT queries. It's also important to keep the pairs together because I don't want to return an errant phone/email combination that wasn't requested.

I could do something like this, but for the possibility of several hundred values the query will be really long.

SELECT * FROM email_phone_notes WHERE ( 
  (email='foo@bar.com' && phone='555-1212') || 
  (email='test@test.com' && phone='888-1212') || 
   ...

Is there a more elegant solution, or should I stick with this? Thanks!

回答1:

If you're after elegant SQL, you could use row constructors:

SELECT * FROM email_phone_notes WHERE (email, phone) IN (
  ('foo@bar.com'  , '555-1212'),
  ('test@test.com', '888-1212')
  -- etc.
);

However, that's not at all index-friendly and would not be recommended on a table of any significant size. Instead, you could materialise a table with your desired pairs and join that with your table:

SELECT * FROM email_phone_notes NATURAL JOIN (
  SELECT 'foo@bar.com' AS email, '555-1212' AS phone
UNION ALL
  SELECT 'test@test.com', '888-1212'
-- etc.
) t;

Or else pre-populate a (temporary) table:

CREATE TEMPORARY TABLE foo (PRIMARY KEY (email, phone)) Engine=MEMORY
  SELECT email, phone FROM email_phone_notes WHERE FALSE
;

INSERT INTO foo
  (email, phone)
VALUES
  ('foo@bar.com'  , '555-1212'),
  ('test@test.com', '888-1212')
  -- etc.
;

SELECT * FROM email_phone_notes NATURAL JOIN foo;

回答2:

You can use a row constructor like this:

SELECT *
FROM email_phone_notes
WHERE (email, phone) IN (
  ('foo@bar.com', '555-1212'),
  ('test@test.com', '888-1212')
)

SQLfiddle example

来源：https://stackoverflow.com/questions/13426203/mysql-how-to-bulk-select-rows-with-multiple-pairs-in-where-clause

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mysql

sql

mysql-5.5