I am wanting to select the 3 biggest selling records with this is my table
CREATE TABLE IF NOT EXISTS `contas` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`id_service` int(11) DEFAULT NULL,
`data` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=28 ;
the 'id_service' is the main column, the more sales, more records are added with the same 'id_service'.
so how do I do this without using PHP and select in descending order?
I tried this
select id_service, count(*) as id_service
from vendas WHERE id_service is not null
group by id_service order by id_service desc LIMIT 3
You have aliased both columns to the same name. No wonder the query is confused. Try this:
select id_service, count(*) as cnt
from vendas WHERE id_service is not null
group by id_service
order by cnt desc
LIMIT 3;
Related
I'm trying to create a ranking table based on how many likes/upvotes a user had on all his items in total. User in the upvotes table links to id of the user that made the like, but I think you don't need this.
Hopefully by giving these tables everything will get clear.
I think the trick here is to get all the upvotes by each item and merge them together towards a user this item was from to get a total likes for each user and then rank all the users based on this total. Of course doing this will probably be a slow query so I need a very performant way to handle this.
The hard thing is here mainly that the upvotes table doesn't include the user id.
3 tables:
CREATE TABLE `items` (
`id` int(255) NOT NULL AUTO_INCREMENT,
`user_id` int(255) NOT NULL,
`img` varchar(500) NOT NULL,
`message` varchar(200) NOT NULL,
`created_on` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
`active` int(11) NOT NULL DEFAULT '1',
PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=19 DEFAULT CHARSET=latin1;
CREATE TABLE `upvotes` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`user` int(255) NOT NULL,
`item_id` int(255) NOT NULL,
`created_on` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
PRIMARY KEY (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=4 DEFAULT CHARSET=latin1;
CREATE TABLE `users` (
`id` int(255) NOT NULL AUTO_INCREMENT,
`email` varchar(255) NOT NULL,
`password` binary(60) NOT NULL,
`first_name` varchar(255) NOT NULL,
`last_name` varchar(255) NOT NULL,
`active` int(1) NOT NULL DEFAULT '1',
`created_on` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
PRIMARY KEY (`id`),
UNIQUE KEY `email` (`email`)
) ENGINE=MyISAM AUTO_INCREMENT=17 DEFAULT CHARSET=latin1;
I need a performant query giving me the ranking of each user ranked on how many likes they got on all their items?
I managed to write this:
SELECT #rank := #rank + 1 AS rank, m.*
FROM (SELECT
users.first_name as first_name,
users.last_name as last_name,
count(upvotes.item_id) as total
FROM upvotes
INNER JOIN users
ON users.id = (SELECT items.user_id FROM items WHERE items.id = upvotes.item_id LIMIT 1)
GROUP BY users.id
ORDER BY total DESC
) m, (SELECT #rank := 0) r
But I reckon this will be super slow when the database grows...
You can do a simple join query in order to get the total likes for each item of user and order your results with the resulting count in descending order
SELECT u.*,i.*,COUNT(DISTINCT up.user) `total_user_likes_item`
FROM users u
JOIN items i ON(i.user_id = u.id)
JOIN upvotes up ON(up.item_id = i.id)
GROUP BY u.id,i.id
ORDER BY u.id,i.id,total_user_likes_item DESC
Edit from comments For user total likes you remove i.id from group by as below query
SELECT u.*,COUNT(DISTINCT up.user) `total_user_likes_item`
FROM users u
JOIN items i ON(i.user_id = u.id)
JOIN upvotes up ON(up.item_id = i.id)
GROUP BY u.id
ORDER BY total_user_likes_item DESC
I'll try answer your question:
In table users you can add row sum_upvotes. Every time when someone get one like (vote) you will increment this column by:
UPDATE users
SET sum_upvotes = sum_upvotes + 1
;
Of course, you will insert a column in table upvotes.
Finally, you query to select users and order them by upvotes will look like this
SELECT first_name, last_name
FROM users
ORDER BY sum_upvotes
;
Hope this helps.
I have 2 separate tables, both of which I need to query simultaneously to get the correct information to display. The tables are members and posts. Through an html form, a user enters criteria for the members table, and then I need to use the primary index of all those specific members to find all the posts submitted by those members and then do a sort on the posts table results. The results will be a mixture of rows from the two tables. Both tables have a primary index of the name 'id'. So far what I've come up with is:
$sql_get_posts = mysqli_query($link, "(SELECT id, username FROM members WHERE active='y' AND gender='M' AND city='Yuma' AND state='Arizona') UNION (SELECT * FROM posts WHERE member_id='id' AND active='y' ORDER BY list_weight DESC)") or die(mysqli_error($link));
The error I'm getting is "The used SELECT statements have a different number of columns".
I need to then cycle through the returned results from both tables to populate the content seen by the user:
<?php
while ($row = mysqli_fetch_array($sql_get_posts)) {
$post_id = $row['id']; //This should be the post primary index named 'id', not the member primary index also name 'id'
$member_id = $row['member_id']; //This is the member_id row in the post table referencing this particular member who wrote this post
$member_username = $row['username']; //This is a row stored in the member table
$title = $row['title']; //This is a row stored in post table
******//and on and on getting rows from only the post table
}
Edit My SQL tables:
CREATE TABLE IF NOT EXISTS `members` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`username` varchar(20) NOT NULL,
`age` varchar(3) NOT NULL,
`gender` varchar(1) NOT NULL,
`city` varchar(20) NOT NULL,
`state` varchar(50) NOT NULL,
`active` enum('y','n') NOT NULL DEFAULT 'y',
`created_date` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=3 ;
CREATE TABLE IF NOT EXISTS `posts` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`member_id` int(11) NOT NULL,
`title` text NOT NULL,
`comments` enum('y','n') NOT NULL DEFAULT 'y',
`post_date` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
`list_weight` double NOT NULL,
`active` enum('y','n') NOT NULL DEFAULT 'y',
PRIMARY KEY (`id`)
) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=47 ;
Use join instead of union, union assumes the tables you're combining are similar, whereas join merges the columns of two tables.
Something like:
SELECT members.id, members.username, posts.*
FROM members
INNER JOIN posts
ON members.id = posts.member_id
WHERE members.active='y' AND members.gender='M' AND members.city='Yuma' AND members.state='Arizona'
ORDER BY posts.list_weight DESC
SELECT statement within the UNION must have the same number of columns. The columns must also have similar data types. Also, the columns in each SELECT statement must be in the same order.
But you have selected only 2 columns in first query and "*" for second select query
use joins
SELECT m.id, m.username,p.* FROM members m JOIN posts p on m.active='y' AND m.gender='M' AND m.city='Yuma' AND m.state='Arizona' and p.member_id='id' AND p.active='y' ORDER BY p.list_weight DESC
or you can use
SELECT m.id, m.username,p.* FROM members m,posts p where m.active='y' AND m.gender='M' AND m.city='Yuma' AND m.state='Arizona' and p.member_id='id' AND p.active='y' ORDER BY p.list_weight DESC
I am trying to make a printable page, where there is all the sales of a specified manufacturer, listing all the products, between specified dates. If there has not been any sales, it should display 0.
The tables
// Manufacturer table
// mid, manufacturer
// Products table
// pid, product, ref_manufacturer_id
// Orders table
// oid, orderPrice, orderDateTime, ref_product_id
And the query that works (without date limitation)
SELECT prod.product, COALESCE(COUNT(pord.oid),0) AS orderCount,
COALESCE(SUM(pord.orderPrice),0) AS orderSum
FROM product_manufacturer AS manu
JOIN product_list AS prod ON prod.ref_manufacturer_id = manu.mid
LEFT JOIN product_orders AS pord ON pord.ref_product_id = prod.pid
WHERE manu.mid = :manu_id
GROUP BY prod.product;
But as soon as I add into the WHERE-syntax this
WHERE manu.mid = :manu_id AND DATE(pord.orderDateTime) BETWEEN :orders_start AND :orders_end
I am using PHP PDO on connecting and verifying that the manu_id is int and the orders_start/end is converted to MySQL date format.
But the question I am trying to fidn out is, what is causing the problem, that when I add the date restriction, every product that was not ordered, is not displayed on the output?
SQL on creating the tables
CREATE TABLE product_list (
pid bigint(20) unsigned NOT NULL AUTO_INCREMENT,
product varchar(255) NOT NULL,
ref_manufacturer_id bigint(20) unsigned NOT NULL,
PRIMARY KEY (pid),
KEY ref_manufacturer_id (ref_manufacturer_id)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;
CREATE TABLE product_manufacturer (
mid bigint(20) unsigned NOT NULL AUTO_INCREMENT,
manufacturer varchar(255) NOT NULL,
PRIMARY KEY (mid),
UNIQUE KEY manufacturer (manufacturer)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;
CREATE TABLE product_orders (
oid bigint(20) unsigned NOT NULL AUTO_INCREMENT,
orderPrice float(10,2) NOT NULL,
orderDatetime timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
red_product_id bigint(20) unsigned NOT NULL,
PRIMARY KEY (oid),
KEY red_product_id (red_product_id)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;
What you need is to move the orderDateTime criteria to the join clause instead of where clause like:
SELECT prod.product, COALESCE(COUNT(pord.oid),0) AS orderCount,
COALESCE(SUM(pord.orderPrice),0) AS orderSum
FROM product_manufacturer AS manu
JOIN product_list AS prod ON prod.ref_manufacturer_id = manu.mid
LEFT JOIN product_orders AS pord
ON pord.ref_product_id = prod.pid
AND DATE(pord.orderDateTime) BETWEEN :orders_start AND :orders_end
WHERE manu.mid = :manu_id
GROUP BY prod.product;
The reason it does not work within the WHERE clause is because of the NULL values returned from the outer join. When you do not have a row in product_orders fot a product, the outer join returns a NULL for the date field orderDateTime and that row will be filtered out because a NULL is not equal to anything.
Try:
SELECT p.product,
COALESCE(o.orderCount, 0) as orderCount,
COALESCE(o.orderSum,0) AS orderSum
FROM product_manufacturer AS m
JOIN product_list AS p ON p.ref_manufacturer_id = m.mid
LEFT JOIN (
SELECT ref_product_id as pid, COUNT(oid) AS orderCount, SUM(orderPrice) AS orderSum
FROM product_orders
WHERE DATE(orderDateTime) BETWEEN :orders_start AND :orders_end
GROUP BY ref_product_id
) AS o ON p.pid = o.pid
WHERE m.mid = :manu_id
Edit: Corrected after ypercube comment.
try this on the where clause.
WHERE manu.mid = :manu_id AND (DATE(pord.orderDateTime) BETWEEN :orders_start AND :orders_end)
It might be reading the second AND function as another where clause that the statement should return true. Just a hunch on that. Let me know if this does the trick.
I don't know how your specific system works, but it may be orderDateTime is not set (ie, NULL or something else) until that product gets ordered. You may want to try:
WHERE manu.mid = :manu_id AND ((DATE(pord.orderDateTime) BETWEEN :orders_start AND :orders_end) OR pord.orderDateTime=NULL)
If this is not the case, could you give an example of the orderDateTime value for something that is not showing up when you want it to?
I am trying to make some sort of SQL Query where I only get the 10 people with the most referrals, but with minimum 1 referral.
My Table looks like this:
CREATE TABLE IF NOT EXISTS `beta_list` (
`id` int(10) NOT NULL AUTO_INCREMENT,
`email` varchar(250) NOT NULL,
`referrer` int(10) NOT NULL,
`referral_code` int(10) NOT NULL,
UNIQUE KEY `id` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1;
I have tried something like this:
SELECT
email,
referral_code as refcode,
(SELECT COUNT(*) FROM beta_list WHERE referrer=refcode) as referrals
FROM
beta_list
WHERE
referrals > 0
ORDER BY
referrals DESC
LIMIT
10
But it just says "Unknown column 'referrals' in 'where clause'".
I am no sql guru, I am only just beginning to learn more complex sql queries, so any help on how to achieve something like this would be deeply appreciated!
Cheers!
Try this - Add an outer query to extract the results from inner query -
select ref.email, ref.refcode, ref.referrals from
(
SELECT
email,
referral_code as refcode,
(SELECT COUNT(*) FROM beta_list WHERE referrer=refcode) as referrals
FROM
beta_list
) as ref
WHERE
ref.referrals > 0
ORDER BY
ref.referrals DESC
LIMIT
10
Give this a go:
SELECT email,referral_code as refcode,count(*) as referrals
FROM beta_list
WHERE referrer = referral_code
GROUP BY email,referral_code
ORDER BY referrals DESC
LIMIT 10;
How to change the order of rows in order to have the rows ordered by custom_field?
For example I have got table with id asc and would like to have the rows in the desc order. I need it in order not to use the 'order by id desc' in the mysql query to optimize the query speed.
I tried:
insert table_with_ordered_rows()
select * from table_with_not_ordered_rows order by id desc;
but it just copy the table with standard asc order.
The only way to get the sorted result set in mysql - is to add ORDER BY in query.
in the mysql query to optimize the query speed.
It is incorrect. If you have issues with query performance - then ask about query performance. Give us complete table structure, the query, the explain and statistics about data.
The only way to guarantee order in a result set is to use an ORDER BY clause. An ORDER BY can make use of an index, if one exists...
That said, the following worked for me on MySQL 5.1.49:
CREATE TABLE `t1` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`col` varchar(45) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=latin1$$
INSERT INTO t1 (col) VALUES ('a'),('b'),('c');
Result set:
id col
--------
1 a
2 b
3 c
Intermediate table:
CREATE TABLE `t2` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`col` varchar(45) DEFAULT NULL,
`old_id` int(11) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=latin1$$
INSERT INTO t2 (col, old_id)
SELECT t.col, t.id
FROM t1 t
ORDER BY t.id DESC
Result set:
id col old_id
----------------
1 c 3
2 b 2
3 a 1
ALTER `tablename` ORDER BY `orderField` DESC;
But you must execute this query after each insert. See 13.1.7. ALTER TABLE Syntax.