I am a little bit rusty on my SQL and would like some help with these queries that I am struggling getting my head round or even finding out if it is possible.
Hi so I have some tables;
clients,products,clientproducts
when a client opts in for a product that is added to clientproducts, using the clientid and the productid.
the easy query
I want to run a query that will only show me products the client has opted in for.
the harder one
I also want to run a query that will show me just the clients that haven't opted in for a product/s.
Thank you for your help in advance.
Query 1:
SELECT table1.id1 FROM table1
WHERE table1.id1 IN (SELECT table2.foreign_id FROM table2);
Query 2:
SELECT table1.id1 FROM table1
WHERE table1.id1 NOT IN (SELECT table2.foreign_id FROM table2);
here, use LEFT JOIN
SELECT a.*
FROM products a
LEFT JOIN clientproducts b
ON a.productID = b.productID
LEFT JOIN clients c
ON b.clientID = c.clientID AND
c.ClientID = 'clientID HERE'
WHERE c.client IS NULL
OR
SELECT a.*
FROM products a
LEFT JOIN clientproducts b
ON a.productID = b.productID AND
b.ClientID = 'clientID HERE'
WHERE b.productID IS NULL
The easy query
SELECT * FROM clients LEFT JOIN products ON clients.id = products.client_id
The hard query
SELECT * FROM clients WHERE clients.id NOT IN (SELECT clients.id FROM clients LEFT JOIN products ON clients.id = products.client_id)
Get all the products information where client_id = 1
select products.*
from products, clientproducts
where products.id = clientproducts.product_id
and clientproducts.client_id = 1
Get all the clients details who has not opted for any products
select *
from clients
where id not in (select client_id
from clientproducts)
Related
I'm new to this, so I know I'm missing something simple, but I can't figure it out. I'm trying to join 3 tables together and I've got it working with 2 joins, but when combined in the same query, there ends up being an error.
My 3 tables are:
TBL_Authors
Author_ID
Author_Name
TBL_Publishers
Publisher_ID
Publisher_Name
TBL_Books
Title
Author_ID
Publisher_ID
ISBN
Genre
Price
Cost
Rating
What I have that isn't working:
$query = 'SELECT * FROM TBL_PUBLISHERS
JOIN TBL_BOOKS ON TBL_PUBLISHERS.Publisher_ID = TBL_BOOKS.Publisher_ID
SELECT * FROM TBL_AUTHORS
JOIN TBL_BOOKS ON TBL_AUTHORS.Author_ID = TBL_BOOKS.Author_ID
ORDER BY TBL_BOOKS.Title ASC;';
This query assumes that each book was published.
SELECT
*
FROM
TBL_Books b
INNER JOIN TBL_Publishers p ON b.Publisher_ID = p.Publisher_ID
INNER JOIN TBL_Authors a ON b.Author_ID = a.Author_ID
ORDER BY
b.Title
Book will always have an Author, but not necessarily a Publisher, if it's not published. If you need to fetch all the books irrespective of whether published or not, you will have to change INNER join on TBL_Publishers to LEFT.
This Query Will show you the result of all details of book, publisher name, author name.
SELECT
t1.* , t2.Publisher_Name , t3.Author_Name
FROM
TBL_Books as t1
INNER JOIN TBL_Publishers as t2 ON t1.Publisher_ID = t2.Publisher_ID
INNER JOIN TBL_Authors as t3 ON t1.Author_ID = t2.Author_ID
ORDER BY
t1.Title
Check This and update if this query helps you.
I have a pretty big query which is used by an ajax call to return and also sort active items. From my understanding sub queries should be avoided where possible and since this query will be called very often, I would like to do just that.
At the moment everything is fine except for the COUNT(b.bic) AS bids. If there are two(2) bids the query returns four(4), if there are 4, it returns 8, and so on. I've tried grouping by other columns ... but no luck.
Some of the tables. I hope each of the column names are pretty self explanatory:
countries_ship - each item can be shipped to multiple countries so item_id can be duplicate.
id item_id country_id ship_cost
countries
id country_code country_name
item_expire - not sure if item_expire should have it's own table.
id item_id exp_date
bids - Just as countries_ship, item_id can be duplicate. This is where the bids are stored.
id item_id user_id bid previous_bid bid_date
The query:
$q = $this->db->mysqli->prepare("
SELECT c.ship_cost,
c.item_id,
co.country_name,
co.id AS co_id,
i.id,
i.user_id,
i.item_start,
i.item_title,
i.item_number,
i.item_year,
i.item_publisher,
i.item_condition,
i.item_description,
i.item_location,
e.exp_date AS exp_date,
i.active,
CAST(u.fb_id AS CHAR(50)) AS fb_id,
u.user_pic,
MAX(b.bid) AS maxbid,
COUNT(b.bid) AS bids,
p.publisher_name,
t.tag_name
FROM countries_ship c
JOIN items i
ON c.item_id = i.id
JOIN item_expire e
ON c.item_id = e.item_id
JOIN users u
ON i.user_id = u.id
LEFT JOIN bids b
ON i.id = b.item_id
LEFT JOIN publishers p
ON i.item_publisher = p.id
LEFT JOIN tags_rel tr
ON c.item_id = tr.item_id
JOIN tags t
ON t.id = tr.tag_id
LEFT JOIN countries co
ON i.item_location = co.id
WHERE ".$where."
GROUP BY c.item_id ORDER BY ".$order." ".$limit."");
You may try
COUNT(distinct b.bic) AS bids
This will ignore duplicates due to joins
I have a Products table and an Orders table defined in such a way that I can do JOIN query as the following to return Products with zero orders for a specific user.
This query works but its very slow.
select * from products where id not in (select product_id from orders where user_id = 1)
The question is, how to write same query better way and faster?
No need of a subquery for that:
SELECT p.product_id
FROM
Products p
LEFT JOIN Order o ON p.product_id = o.product_id AND o.user_id = #UserId
WHERE
o.order_id IS NULL -- or any other field that cannot be null on Order
EDIT: for increased performance you may want to check as well that you have indexes in place on the Order user_id column and on your ids (more likely you have them there and probably clustered indexes, both worth to check)
You should be able to do simple LEFT JOIN
SELET * FROM products
LEFT JOIN orders ON (orders.product_id=products.id and orders.user_id=1)
WHERE orders.id IS NULL;
SELECT P.*
FROM products P
LEFT JOIN (SELECT product_id from orders where user_id = 1) O
ON P.id = O.product_id
WHERE O.product_id IS NULL
I have the following query which works perfectly:
SELECT *
FROM contacts
WHERE id in (
SELECT DISTINCT contacts.id
FROM contacts
INNER JOIN contacts2tags
ON contacts.id = contacts2tags.contactid
WHERE tagid in(7,4)
)
Here contacts table contains id, first_name, last_name, ..and tags table contains id, name. contacts2tags table contains contactid and tagid which are same as contacts.id and tags.id respectively
Now, what I want is, to display only the contacts which have both a tagid 7 and a tagid 4.
I tried something like this:
SELECT *
FROM contacts
WHERE id IN
(
SELECT CT1.contactid
FROM
tags T1, contacts2tags CT1, tags T2, contacts2tags CT2
WHERE CT1.contactid = CT2.contactid
AND CT1.tagid = T1.id
AND CT2.tagid = T2.id
AND (T1.id = 7 AND T2.id = 4)
and it works too.
My problem is, I want to convert the above second query to one using inner joins.
I have an array of ids stored in $tmp in php
I want to use those ids and write the above query for them.
How do I do that? I am not comfortable with sql. Might be its a very simple thing to ask.
Thanks in advance
EDIT:
The answer below solved the problem. But the sql runs very slow for 10k records. Any suggestions to optimise it? Pasting the updated query as given in the answer.
SELECT c.id
FROM contacts c
inner join contacts2tags t on c.id = t.contactid
where t.tagid in (7,4)
group by c.id
having count(distinct t.tagid) = 2
This should work
SELECT c.id
FROM contacts c
inner join contacts2tags t on c.id = t.contactid
where t.tagid in (7,4)
group by c.id
having count(distinct t.tagid) = 2
I've got reporting of a user's score everytime it happens. Now I want to show the best score a user has had. The table set up is like this:
Player(id, name)
PlayerHasAchievement(id, playerId,
achievementId)
Achievement(id, type, amount, time)
This is what I have right now:
$query = "SELECT MAX(ach.amount) as amount, p.username, ach.time
FROM achievement as ach
INNER JOIN playerHasAchievement as playAch ON ach.id = playAch.id
INNER JOIN player as p ON p.userId = playAch.userid
WHERE ach.type = 2
GROUP BY amount
ORDER by `amount` DESC
LIMIT $amount";
I tried to select it distinctly but it didn't work. I'm stumped, it's supposed to be so easy! Thanks for reading, I'll be grateful for any help!
The problem is the the ach.time you are getting is not the same row as the MAX(amount). Join another subquery to get the MAX(amount) first.
Note: In the table definitions you posted, playerHasAchievement has a field playerId not userId
SELECT MAX(ach.amount) as amount, p.username, MAX(ach.time) MaxTime
FROM achievement as ach
INNER JOIN playerHasAchievement as playAch ON ach.id = playAch.id
INNER JOIN player as p ON p.userId = playAch.playerId
INNER JOIN (
SELECT playAch.playerId, MAX(ach.amount) as MaxAmount
FROM achievement as ach
INNER JOIN playerHasAchievement as playAch ON ach.id = playAch.id
WHERE ach.type = 2
GROUP BY playAch.playerId
) g ON p.playerId = g.playerId AND ach.amount = g.MaxAmount
WHERE ach.type = 2
GROUP BY p.playerId
ORDER by `amount` DESC
LIMIT $amount";
The reason why we group the outer query, is to avoid ties - say a player had the same score twice.
In your join on line 3 don't you really want
INNER JOIN playerHasAchievement as playAch ON ach.id = playAch.achievementId
and others are correct, you need to group by your non aggregate columns, not the aggregate one.
Assuming your db layout is as specified in the question here is the query I would use.
SELECT ach.amount, p.Name, ach.time
FROM achievement as ach
JOIN playerHasAchievement as playAch ON ach.id=playAch.achievementId
JOIN player AS p ON p.id = playAch.playerId
WHERE ach.type = 2
AND ach.amount = (SELECT MAX(ach.amount)
FROM achievement as ach
JOIN playerHasAchievement as playAch ON ach.id=playAch.achievementId
JOIN player AS p ON p.id = playAch.playerId
WHERE ach.type = 2)
GROUP BY ach.amount
ORDER by ach.time
taking the first result (in case there are multiples of the same score) will give you the high score and the lowest time.
Hope that helps!
You are not using group by appropriately, as you are only grouping by amount.
What about the user name and the time?