I have 2 tables.
Table A: trades: which contains the columns: tradeID, tradeName, tradeShow, and tradeGuy.
Table B: offers: which contains the columns: tradeID, offerName, offerGuy.
I'm trying to select all columns from table A (trades) WHERE the value of "tradeShow" = 'Yes', And the value of "tradeGuy" != the user's Username. That much is easy, but I also don't want to select any records which have an offer created by the user. In other words, in table B (offers), offerGuy != Username WHERE trade ID from Table B = tradeID from Table A.
But, how do I merge these 2 conditions? I've tried this:
$sql = "SELECT *
FROM trades t1
JOIN offers t2
ON (t1.tradeID = t2.tradeID)
WHERE t1.tradeShow='Yes' AND t1.tradeGuy!='$username' AND t2.offeringGuy!='$username'";
But the problem with that is it only selects the records from trades which have an offer, because of the forth line: ON (t1.tradeID = t2.tradeID), as in it only selects trades which have a record in (offers) that mentions their tradeID.
I've also tried an awkward attempt to link the 2 tables with a meaningless link by adding a "linker" column to each table with the default value of "XXX", and did this:
$sql = "SELECT *
FROM trades t1
JOIN offers t2
ON (t1.linkerA = t2.linkerB)
WHERE t1.tradeShow='Yes' AND t1.tradeGuy!='$username' AND (t2.offeringGuy!='$username' WHERE t1.tradeID=t2.tradeID)";
But the problem with that is using 2 Where clauses...
So, how do I merge the 2 conditions?
What you're looking for is called an OUTER JOIN (in this case a LEFT OUTER JOIN) which will give you null results for missing matches, something like;
SELECT *
FROM trades t1
LEFT OUTER JOIN offers t2
ON t1.tradeID = t2.tradeID AND t2.offeringGuy = '$username'
WHERE t1.tradeShow='Yes' AND t1.tradeGuy!='$username' AND t2.offeringGuy IS NULL
We add a condition to the LEFT JOIN that we're only interested in matches against t2.offeringGuy = '$username', which will return NULL values in t2's fields if there is no match.
Then we just check that t2.offeringGuy IS NULL to find the non matches.
I would do this with not exists rather than an explicit join:
SELECT *
FROM trades t
WHERE t.tradeShow = 'Yes' AND t.tradeGuy <> '$username' and
not exists (select 1
from offers o
where t.tradeID = o.tradeID and o.tradeGuy = '$username'
);
Related
I have two tables, one for registered users and one to store votes.
We are logging in with registrants.id and registrants.zipcode. Once they vote their votes are inserted into the votes table, along with their Registration ID.
Im trying to right a select statement that returns a record that will select all the records for Matched ID and Zipcode, but the ID is not in the Votes.voter column. i have tried all kinds of variations of all the joins i can think of. is it something simple i am missing.
SELECT * FROM registrants
LEFT JOIN votes on registrants.id = votes.voter
WHERE registrants.id = 1 AND registrants.zipcode = 46706 and votes.voter <> 1
Perhaps a not exists query:
select * from registrants
where registrants.zipcode = '46706'
and not exists (select 1 from votes where registrants.id = votes.voter)
I am trying to only show unique userIds (userIds are (0,1,2,3,4,5,6,7,8,9 etc...) for the query I am running. I tried using DISTINCT in my query, but it only shows me unique values of the rows that have 2 or more of the same userId.
Is there a way I can use php to only show the unique values. My weak points are arrays and it makes it more complicated because its using data from a MySQLi query.
Example right now I have with the query now (lets say its GROUP BY rentPaid DESC and the rent total is 800.00 for all users):
userID rentPaid rentMonth
2--------800.00------April
1--------500.00------April
3--------400.00------April
3--------400.00------April
1--------200.00------April
1--------100.00------April
Example desired output:
userID rentPaid rentMonth
2--------800.00------April
1--------500.00------April
3--------400.00------April
Can I do this with MYSQL because I tried DISTINCT and it wouldn't work, how about PHP?
Query:
SELECT
properties.*,
leases.*,
users.userId, users.primaryPhone,
CONCAT(users.userFirstName,' ',users.userLastName) AS user,
admins.adminName, payments.*
FROM
properties
LEFT JOIN leases ON properties.propertyId = leases.propertyId
LEFT JOIN assigned ON properties.propertyId = assigned.propertyId
LEFT JOIN admins ON assigned.adminId = admins.adminId
LEFT JOIN users ON properties.propertyId = users.propertyId
LEFT JOIN payments ON properties.propertyId = payments.propertyId
WHERE
payments.rentMonth = '$currentMonth' AND
payments.rentYear = '$currentYear'
Edit: Please excuse my formatting, this is my first post.
Edit: Added query....its long, but works lol. I only want unique userIds (no double or triple userIds etc...)
I suspect this is what you want:
SELECT userID, MAX(rentPaid) AS maxRentPaid, rentMonth
FROM yourTable
WHERE rentMonth = "April"
GROUP BY userID
ORDER BY maxRentPaid
I keep falling back into questions with MySQL joining.
And I would like to request a very simple example I could use to continue my journey of understanding learning the MySQL syntax.
Let's say I got the following table's
test_testtable
testtable_id
testtable_name
testtable_user
testtable_option
testtable_textfield
test_testlink
testlink_id
testlink_link
testlink_address
test_address
address_id
address_name
address_phone
address_email
address_street
address_city
address_zip
I would like to make a selection like :
SELECT * (lets say I would define the fields) FROM `test_testable`
JOIN `test_testtable`.`testtable_id` = `test_testlink`.`testlink_link`
AND
JOIN `test_testlink`.`testlink_addres` = `test_address`.`address_id`
WHERE `user_id` = 5
Hence the linking structure is like:
test_testtable.testtable_id = leading
table test_testlink is a table to link the table test_testtable and test_address
And linking table test_testlink uses the field testlink_link to link to the table test_testtable, and uses the field testlink_address to link to the table test_address
This does not work. FOR ME.. Since I continuously seem to fail of catching the correct syntax logic.
So I hope that someone could give me a small example of how to correctly implement such a simple yet critical query!
TIAD!!
A general approach :
SELECT table1.* FROM table1
JOIN table2 ON table2.id_table1 = table1.id
JOIN table3 ON table3.id_table2 = table2.id
WHERE table1.id = 10
For your purpose :
SELECT * (lets say I would define the fields) FROM `test_testable`
JOIN `test_testlink` ON `test_testtable`.`testtable_id` = `test_testlink`.`testlink_link`
JOIN `test_address` ON `test_testlink`.`testlink_addres` = `test_address`.`address_id`
WHERE `user_id` = 5
Please read the reference
You are using wrong syntax. You should mention which tables to join first then based on which fields.
SELECT * (lets say I would define the fields) FROM `test_testable`
INNER JOIN test_testlink
ON `test_testtable`.`testtable_id` = `test_testlink`.`testlink_link`
INNER JOIN `test_address`
ON `test_testlink`.`testlink_addres` = `test_address`.`address_id`
AND `test_testtable`.`user_id` = 5
select * from testlink JOIN testtable ON testlink.tableid = testtable.ID
JOIN testaddress ON testlink.addressid = testaddress.ID
WHERE testtable.ID = 5
I have two database tables. One is egl_achievement and the other is egl_achievement_member. One just holds achievements, and the other holds members who have achievements. I'm trying to write a query that will return all achievements a member doesn't have. I thought I could use MINUS, but mysql doesn't support that.
SELECT egl_achievement.id as id FROM egl_achievement LEFT JOIN egl_achievement_member ON egl_achievement.id = egl_achievement_member.egl_achievement_id WHERE egl_achievement_member.member_id =57;
This will obviously return the ids that member 57 has, but how can I get the opposite?
You can use a subselect which contains all achievments and then just list those which are not contained:
SELECT egl_achievement.id as id
FROM egl_achievement
WHERE egl_achievement.id NOT IN(
SELECT egl_achievement_member.egl_achievement_id
FROM egl_achievement_member
WHERE egl_achievement_member.member_id =57);
You should be able to use NOT IN.
This should select all distinct id's which member 57 does not have.
select distinct eql_achievement.id as id
from eql_achievement where eql_achievement.id not in
(SELECT egl_achievement_member.eql_achievement_id as id FROM egl_achievement_member
WHERE egl_achievement_member.member_id =57;)
Right join and filter the ones without id (So those that are not defined in your A table)
SELECT * FROM `egl_achievement_member` `a`
RIGHT JOIN `egl_achievement` `b`
ON `a`.`achievement_id` = `b`.`id`
WHERE `a`.`achievement_id` IS NULL
And then with the user
SELECT * FROM `egl_achievement_member` `a`
RIGHT JOIN `egl_achievement` `b`
ON `a`.`member_id` = 57
AND `a`.`achievement_id` = `b`.`id`
WHERE `a`.`achievement_id` IS NULL
Here is a pretty sweet schedule
I have two mysql tables with content one is called petitions
{"success":1,"petitions":[{"id":"6","name":"should he go","timestamp":"2013-10-26 03:02:44"},{"id":"3","name":"Olara Otunu should get married","timestamp":"2013-10-24 14:33:53"},{"id":"4","name":"Teachers deserve 30 not 20 salary rise","timestamp":"2013-10-24 14:33:53"},{"id":"5","name":"Prostitution should be banned","timestamp":"2013-10-24 14:33:53"},{"id":"1","name":"Has Jennifer Musisi done great work for Kampala","timestamp":"2013-10-24 14:32:58"},{"id":"2","name":"Do lecturers deserve 100% salary increase","timestamp":"2013-10-24 14:32:58"}]}
and the other table is called petition_response
{"success":1,"petition_response":[{"id":"2","petitionID":"2","yes":"0","no":"1","memberID":"14","timestamp":"2013-11-02 08:36:20"},{"id":"1","petitionID":"1","yes":"1","no":"0","memberID":"14","timestamp":"2013-11-01 21:26:02"}]}
I need to select * petitions which have no response in the petition_response. But if they have any response in the petition_response table then the memberID should not be equal to 14
I have tried this code below but its not working
$result = mysql_query("select * from petition_response where memberID='14' order by timestamp DESC", $db->connect());
while($row = mysql_fetch_assoc($result)){
$id = $row['id'];
$result2 = mysql_query("select * from petitions where id != '$id' order by timestamp DESC", $db->connect());
}
return $result2;
You're looking to effect an anti-join, for which there are three possibilities in MySQL:
Using NOT IN:
SELECT *
FROM petitions
WHERE id NOT IN (
SELECT petitionID
FROM petition_response
WHERE memberID = 14
)
Using NOT EXISTS:
SELECT *
FROM petitions p
WHERE NOT EXISTS (
SELECT *
FROM petition_response r
WHERE r.petitionID = p.id
AND r.memberID = 14
LIMIT 1
)
Using an OUTER JOIN:
SELECT p.*
FROM petitions p
LEFT OUTER JOIN petition_response r
ON r.petitionID = p.id AND r.memberID = 14
WHERE r.petitionID IS NULL
See them on sqlfiddle.
According to #Quassnoi's analysis:
Summary
MySQL can optimize all three methods to do a sort of NESTED LOOPS ANTI JOIN.
It will take each value from t_left and look it up in the index on t_right.value. In case of an index hit or an index miss, the corresponding predicate will immediately return FALSE or TRUE, respectively, and the decision to return the row from t_left or not will be made immediately without examining other rows in t_right.
However, these three methods generate three different plans which are executed by three different pieces of code. The code that executes EXISTS predicate is about 30% less efficient than those that execute index_subquery and LEFT JOIN optimized to use Not exists method.
That’s why the best way to search for missing values in MySQL is using a LEFT JOIN / IS NULL or NOT IN rather than NOT EXISTS.
$query = "
SELECT *
FROM petition_response pr
LEFT
JOIN petitions p
ON p.id = pr.id
WHERE pr.memberID = 14
AND p.id IS NULL
ORDER
BY pr.timestamp DESC;
";