MySQL Join with multiple conditions

Question

I have a problem with an sql query, actually a simple query but I can\'t figure up what am I missing, so I came to ask your help... So, what i have to do

I have two

Answer 1

If you join the facilities table twice you will get what you are after:

select u.* 
from room u 
  JOIN facilities_r fu1 on fu1.id_uc = u.id_uc and fu1.id_fu = '4'
  JOIN facilities_r fu2 on fu2.id_uc = u.id_uc and fu2.id_fu = '3' 
where 1 and vizibility='1' 
group by id_uc 
order by u_premium desc, id_uc desc

Answer 2

also this should work (not tested):

SELECT u.* FROM room u JOIN facilities_r fu ON fu.id_uc = u.id_uc AND u.id_fu IN(4,3) WHERE 1 AND vizibility = 1 GROUP BY id_uc ORDER BY u_premium desc , id_uc desc

If u.id_fu is a numeric field then you can remove the ' around them. The same for vizibility. Only if the field is a text field (data type char, varchar or one of the text-datatype e.g. longtext) then the value has to be enclosed by ' or even ".

Also I and Oracle too recommend to enclose table and field names in backticks. So you won't get into trouble if a field name contains a keyword.

Answer 3

SELECT 
    u . *
FROM
    room u
        JOIN
    facilities_r fu ON fu.id_uc = u.id_uc
        AND (fu.id_fu = '4' OR fu.id_fu = '3')
WHERE
    1 and vizibility = '1'
GROUP BY id_uc
ORDER BY u_premium desc , id_uc desc

You must use OR here, not AND.

Since id_fu cannot be equal to 4 and 3, both at once.

Answer 4

You can group conditions with parentheses. When you are checking if a field is equal to another, you want to use OR. For example WHERE a='1' AND (b='123' OR b='234').

SELECT u.*
FROM rooms AS u
JOIN facilities_r AS fu
ON fu.id_uc = u.id_uc AND (fu.id_fu='4' OR fu.id_fu='3')
WHERE vizibility='1'
GROUP BY id_uc
ORDER BY u_premium desc, id_uc desc