MySQL query using AND & OR operators

Question

The query below loads all conversations, however, I wanted to only load the conversation between two people.

SELECT * FROM msg 
WHERE senderid = '{$sender}' 
OR recid = '{$recipient}' 
OR recid = '{$sender}' 
OR senderid = '{$recipient}' 
order by id asc

How would I use the AND & OR operators together? Would the following work?

SELECT * FROM msg 
WHERE senderid = '{$sender}' 
AND recid = '{$recipient}' 
OR recid = '{$sender}' 
AND senderid = '{$recipient}' 
order by id asc

Still, be careful with mixing AND and OR in boolean expressions. It is easy to make mistakes. Use parentheses to be safe. — Bart Friederichs
– Bart Friederichs, Commented Aug 21, 2012 at 14:44

Adriano Carneiro · Accepted Answer · 2012-08-21 14:50:16Z

4

When using AND and OR together, use parentheses to group your logic and make sure the it does what you expect:

SELECT * FROM msg 
WHERE (senderid = '{$sender}' AND recid = '{$recipient}')
OR    (recid = '{$sender}' AND senderid = '{$recipient}')
order by id asc

edited Aug 21, 2012 at 14:50

answered Aug 21, 2012 at 14:40

Adriano Carneiro

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2 Comments

Jose Salvatierra Over a year ago

I'd like to add for other people that it's always much better to have too many parentheses (brackets?) than too few!

Adriano Carneiro Over a year ago

@jslvtr Agreed! On an additional note, further clarification on used terminology can be found here: en.wikipedia.org/wiki/Bracket :)

Adriano Carneiro · Accepted Answer · 2012-08-21 14:48:00Z

0

Please find below.

SELECT * FROM msg 
WHERE (senderid = '{$sender}' AND recid = '{$recipient}') 
OR (recid = '{$sender}' AND senderid = '{$recipient}') 
order by id asc

edited Aug 21, 2012 at 14:48

Adriano Carneiro

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answered Aug 21, 2012 at 14:44

Haris Iltifat

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