Table structure
client_commands (the "main" table):
id | completed
command_countries:
id | command_id | country_code
command_os:
id | command_id |OS
command_id on references the id column on client_commands.
Problem
I can add client commands with filters based on countries and operating systems. To try and normalise my DB structure, for each new command added:
Add a new row to client_commands
For each country, I add a new row to command_countries, each referencing client_command.id
For each OS, I add a new row to command_os, each referencing client_command.id
For one of the pages on my site, I need to display all client_commands (where completed = 0) as well as all the countries and operating systems for that command. My desired output would be something like:
id | countries | OS
1 | GB, US, FR| 2, 3
2 | ES, HU | 1, 3
I'm not sure how to go about doing this. The current query I'm using returns multiple rows:
SELECT a.id, b.country_code, c.OS
FROM client_commands a
LEFT JOIN command_countries b on b.command_id = a.id
LEFT JOIN command_os c on c.command_id = a.id
WHERE a.completed = 0
Any help?
Thanks!
EDIT: I forgot to mention (if you couldn't infer from above) - there can be a different number of operating systems and countries per command.
--
Also: I know I could do this by pulling all the commands, then looping through and running 2 additional queries for each result. But if I can, I'd like to do it as efficiently as possible with one query.
You can do this in one query by using GROUP_CONCAT
SELECT a.id,
GROUP_CONCAT(DISTINCT b.country_code SEPARATOR ' ,') `countries`,
GROUP_CONCAT(DISTINCT c.OS SEPARATOR ' ,') `os`,
FROM client_commands a
LEFT JOIN command_countries b on b.command_id = a.id
LEFT JOIN command_os c on c.command_id = a.id
WHERE a.completed = 0
GROUP BY a.id
if you want the ordered results in in a row you can use ORDER BY in GROUP_CONCAT like
GROUP_CONCAT(b.country_code ORDER BY b.command_id DESC SEPARATOR ' ,') `countries`
But be aware of that fact it has a limit of 1024 character to concat set by default but this can be increased b,steps provided in manual
Related
This question already has answers here:
How to resolve ambiguous column names when retrieving results?
(11 answers)
Closed 2 years ago.
I have some big tables which I need to combine into a single very large table, to form a single-page data export for a statistical package.
This is easy with INNER JOIN but the some of the tables have the same column names and these are being overwritten by each other when I fetch them as an array in PHP.
There are 4 tables being joined with 30-200 columns in each so there are far too many field names to manually include in the query with aliases, as would be the norm in this situation.
Here's the query:
SELECT * FROM logs
INNER JOIN logdetail ON logdetail.logID = logs.id
INNER JOIN clients ON clients.id = logs.clientID
INNER JOIN records ON records.id = logdetail.id
WHERE logs.userID=1
Is there any way around this? I don't actually mind what the column names are as long as I have the data so if I could prepend the table name to each field, that would do the trick.
I would create a view, your view would be comprised of your long query with aliases
Here is an example taken from the manual
mysql> CREATE TABLE t (qty INT, price INT);
mysql> INSERT INTO t VALUES(3, 50);
mysql> CREATE VIEW v AS SELECT qty, price, qty*price AS value FROM t;
mysql> SELECT * FROM v;
+------+-------+-------+
| qty | price | value |
+------+-------+-------+
| 3 | 50 | 150 |
+------+-------+-------+
This has always worked for me, unless you have one to many or some other relationship among these tables, which will duplicate records.
SELECT * FROM logs l
INNER JOIN logdetail ld ON ld.logID = l.id
INNER JOIN clients c ON c.id = l.clientID
INNER JOIN records r ON r.id = ld.id
WHERE l.userID=1
As andrew says you can also use a View to get this thing working which is much cooler.
I found a solution for this. Simply, fetch each duplicate column a second time, this time using an alias. This way, the overwritten values are selected again and aliased:
SELECT * FROM logs,
clients.name as clientName,
logs.name as logName,
etc...
INNER JOIN logdetail ON logdetail.logID = logs.id
INNER JOIN clients ON clients.id = logs.clientID
INNER JOIN records ON records.id = logdetail.id
WHERE logs.userID=1
Note: There is no need to do this for the final instance of the duplicate, because this column will not have been overwritten. So, in the example above, there is no need to include a line like records.name as recordName because, since there are no columns after it which have the same name, the record.name field was never overwritten and is already available in the name column.
I'm trying to query information from two different tables, but I'm not figuring out how to do it best. As a disclaimer, I'm still learning MySQL/PHP, and I don't have control over the tables as they're set up - I'm trying to work with what I've got, since I can't add/change the tables. Below are the tables and the relevant attributes:
Table(attribute1, attribute2, ...);
------------------------------------
reports(id, reporter_id, added)
report_comments(comment_id, report_id, comment_text, commenter_id)
The reporter_id refers to the user who filed a report, and commenter_id is not the same person as reporter_id.
I want to get a count of how many report comments have, for example, the word "incorrect" in comment_text, for each reporter_id. I then want to make a table that shows each reporter's ID and the number of comments that are associated with that reporter's reports since "1383359439" (timestamp).
So far, I've not been very successful. My current query looks like this:
SELECT r.id, r.reporter_id,
(SELECT COUNT(*) FROM report_comments WHERE comment_text LIKE '%incorrect%' AND report_id = r.id) AS comments
FROM reports AS r
LEFT JOIN report_comments AS rc ON r.id = rc.report_id
WHERE r.added > 1383359439
GROUP BY r.reporter_id;
The resulting page, when I set the HTML table to list "reporter_id" followed by "comments", gives everyone who has filed a report since the time listed, but the count is either "0" or "1", with any reporter who has had "incorrect" in any report comment getting a "1" and those without "incorrect" getting "0":
Reporter1 | 0
Reporter2 | 1
Reporter3 | 0
Reporter4 | 1
Reporter5 | 1
The thing is, some reporters have had several comments with "incorrect" in them, and I want to get a count of each, and ONLY for those reporters (not ones who've never had an "incorrect" comment). For example:
Reporter2 | 2
Reporter4 | 17
Reporter5 | 3
I'm clearly missing something - what am I doing wrong?
You need to utilize grouping for this.
SELECT
r.reporter_id AS `reporter_id`,
COUNT(rc.report_id) AS `incorrect_count`
FROM reports AS r
INNER JOIN report_comments AS rc
ON r.id = rc.report_id
WHERE rc.comment_text LIKE '%incorrect%'
AND r.added > ?
GROUP BY `reporter_id`
Here ? represents the timestamp you are trying to compare against.
To answer your follow-up question, there are a couple of ways to do this. I might suggest use of SUM() in conjunction with CASE like this:
SELECT
r.reporter_id AS `reporter_id`,
SUM(
CASE WHEN rc.comment_text LIKE '%incorrect%'
THEN 1
ELSE 0
END CASE
) AS `incorrect_count`,
SUM(
CASE WHEN rc.comment_text LIKE '%fake%'
THEN 2
ELSE 0
END CASE
) AS `fake_count`,
FROM reports AS r
INNER JOIN report_comments AS rc
ON r.id = rc.report_id
WHERE
rc.comment_text LIKE '%incorrect%'
OR rc.comment_text LIKE '%fake%'
AND r.added > ?
GROUP BY `reporter_id`
It's something like this:
SELECT r.reporter_id, COUNT(*) comments
FROM reports AS r
INNER JOIN report_comments AS rc ON r.id = rc.report_id
WHERE r.added > 1383359439
AND comment_text LIKE '%incorrect%'
GROUP BY r.reporter_id;
I removed r.id since it doesn't make sense to have in this case as one reporter can have many reports (so multiple r.id).
You could try
SELECT r.id, COUNT(c.id) tot
FROM reports r INNER JOIN report_comments
ON r.id = c.report_id
AND c.comment_text LIKE '%incorrect%'
AND r.added > 1383359439
GROUP BY r.reporter_id
So, I have a table named clients, another one known as orders and other two, orders_type_a and orders_type_b.
What I'm trying to do is create a query that returns the list of all clients, and for each client it must return the number of orders based on this client's id and the amount of money this customer already spent.
And... I have no idea how to do that. I know the logic behind this, but can't find out how to translate it into a MySQL query.
I have a basic-to-thinkimgoodbutimnot knowledge of MySQL, but to this situation I've got really confused.
Here is a image to illustrate better the process I'm trying to do:
Useful extra information:
Each orders row have only one type (which is A or B)
Each orders row can have multiple orders_type_X (where X is A or B)
orders relate with client through the column client_id
orders_type_X relate with orders through the column order_id
This process is being made today by doing a query to retrieve clients, and then from each entry returned the code do another query (with php) to retrieve the orders and yet another one to retrieve the values. So basically for each row returned from the first query there is two others inside it. Needless to say that this is a horrible approach, the performance sucks and I thats the reason why I want to change it.
UPDATE width tables columns:
clients:
id | name | phone
orders:
id | client_id | date
orders_type_a:
id | order_id | number_of_items | price_of_single_item
orders_type_b:
id | order_id | number_of_shoes_11 | number_of_shoes_12 | number_of_shoes_13 | price_of_single_shoe
For any extra info needed, just ask.
If I understand you correctly, you are looking for something like this?
select c.*, SUM(oa.value) + SUM(ob.value) as total
from clients c
inner join orders o on c.order_id = o.id
inner join orders_type_a oa on oa.id = o.order_type_id AND o.type = 'A'
inner join orders_type_b ob on ob.id = o.order_type_id AND o.type = 'B'
group by c.id
I do not know your actual field names, but this returns the information on each customer plus a single field 'total' that contains the sum of the values of all the orders of both type A and type B. You might have to tweak the various names to get it to work, but does this get you in the right direction?
Erik's answer is on the right track. However, since there could be multiple orders_type_a and orders_type_b records for each order, it is a little more complex:
SELECT c.id, c.name, c.phone, SUM(x.total) as total
FROM clients c
INNER JOIN orders o
ON o.client_id = c.id
INNER JOIN (
SELECT order_id, SUM(number_of_items * price_of_single_item) as total
FROM orders_type_a
UNION ALL
SELECT order_id, SUM((number_of_shoes_11 + number_of_shoes_12 + number_of_shoes_13) * price_of_single_shoe) as total
FROM orders_type_b
) x
ON x.order_id = o.id
GROUP BY c.id
;
I'm making a few assumptions about how to calculate the total based on the columns in the orders_type_x tables.
tbl_teams: team_id | team_name
tbl_players: player_id | player_fname | player_sname | player_bplace | player_bdate
tbl_players_stats: player_id | season_id | player_squad_no | team_id | player_apps | player_goals
Sorry if this is a basic question, but from all the MySQL tables and columns above I'd like to join the tables and then display the results by which season_id and team_id is selected. I need using PHP like this:
player_squad_no | player_sname, player_fname | team_name | player_apps | player_goals
I've looked at examples on here but still can't figure out how to write the MySQL query to do it with three separate tables and how to specify the table name before the column name. I've seen some examples with only the initial. tt.teams for instance. Is Left Join the way to do it?
Any help would be much appreciated.
With three separate tables, you simply write the join like this:
SELECT *
FROM Table_A AS A
LEFT JOIN Table_B AS B USING(ID)
LEFT JOIN Table_C AS C USING(ID)
Note that USING(column) is a syntactic alternative to ON A.column = B.column that you can use when the columns you want to join on have the same name in both tables.
In the above example, the tables are aliased with AS so that you can refer to them by the alias instead of the full table name. (AS is actually optional; you can just give the alias immediately after the table, if you're paying by the character.) Try to choose an alias that makes sense when you look at it; often times people will alias like this:
SELECT a.Name, b.State
FROM Customers AS a
LEFT JOIN Orders AS b
...etc.
But if you have a longer query, how are you supposed to remember what tables a and b refer to? At the very least, it would make sense to alias Customers AS C and Orders AS O; in some cases, I would go a step further: Registration AS REG, for instance. This gets more and more important as you JOIN more and more tables together.
Here's one way to write your query:
SELECT
Stats.player_squad_no,
CONCAT_WS(', ', Players.player_sname, Players.player_fname) AS player_full_name,
Teams.team_name,
Stats.player_apps,
Stats.player_goals
FROM tbl_players AS Players
LEFT JOIN tbl_players_stats AS Stats USING(player_id)
LEFT JOIN tbl_teams AS Teams USING(team_id)
The CONCAT_WS() function is included to assemble the player's full name the way you indicated you wanted it to be displayed. Since this function will output a column with a messy name, I also gave it an alias.
This should work
SELECT tbl_players_stats.player_squad_no,
tbl_players.player_sname,
tbl_players.player_fname,
tbl_teams.team_name,
tbl_players_stats.player_apps,
tbl_players_stats.player_goals
FROM tbl_players
JOIN tbl_players_stats ON tbl_players.player_id = tbl_players_stats.player_id
JOIN tbl_teams ON tbl_teams.team_id = tbl_players_stats.team_id
SELECT player_squad_no , player_sname, player_fname,team_name, player_apps, player_goals
FROM tbl_players_stats as s
JOIN tbl_players as p ON s.player_id=p.player_id
JOIN tbl_teams as t ON s.team_id=t.team_id
Nothing Joining is simple concept. But we should use proper columns for tables. While selecting the list of columns to select we should be little careful by using table aliasing. Try the below code
select c.player_squad_no,b.player_sname,b.player_fname,a.team_name,c.player_apps,c.player_goals
from tbl_teams a,tbl_players b,tbl_players_stats c
where a.team_id=c.team_id
and b.player_id=c.player_id
I have the following database structure:
Sites table
id | name | other_fields
Backups table
id | site_id | initiated_on(unix timestamp) | size(float) | status
So Backups table have a Many to One relationship with Sites table connected via site_id
And I would like to output the data in the following format
name | Latest initiated_on | status of the latest initiated_on row
And I have the following SQL query
SELECT *, `sites`.`id` as sid, SUM(`backups`.`size`) AS size
FROM (`sites`)
LEFT JOIN `backups` ON `sites`.`id` = `backups`.`site_id`
WHERE `sites`.`id` = '1'
GROUP BY `sites`.`id`
ORDER BY `backups`.`initiated_on` desc
The thing is, with the above query I can achieve what I am looking for, but the only problem is I don't get the latest initiated_on values.
So if I had 3 rows in backups with site_id=1, the query does not pick out the row with the highest value in initiated_on. It just picks out any row.
Please help, and
thanks in advance.
You should try:
SELECT sites.name, FROM_UNIXTIME(b.latest) as latest, b.size, b.status
FROM sites
LEFT JOIN
( SELECT bg.site_id, bg.latest, bg.sizesum AS size, bu.status
FROM
( SELECT site_id, MAX(initiated_on) as latest, SUM(size) as sizesum
FROM backups
GROUP BY site_id ) bg
JOIN backups bu
ON bu.initiated_on = bg.latest AND bu.site_id = bg.site_id
) b
ON sites.id = b.site_id
In the GROUP BY subquery - bg here, the only columns you can use for SELECT are columns that are either aggregated by a function or listed in the GROUP BY part.
http://dev.mysql.com/doc/refman/5.5/en/group-by-hidden-columns.html
Once you have all the aggregate values you need to join the result again to backups to find other values for the row with latest timestamp - b.
Finally join the result to the sites table to get names - or left join if you want to list all sites, even without a backup.
Try with this:
select S.name, B.initiated_on, B.status
from sites as S left join backups as B on S.id = B.site_id
where B.initiated_on =
(select max(initiated_on)
from backups
where site_id = S.id)
To get the latest time, you need to make a subquery like this:
SELECT sites.id as sid,
SUM(backups.size) AS size
latest.time AS latesttime
FROM sites AS sites
LEFT JOIN (SELECT site_id,
MAX(initiated_on) AS time
FROM backups
GROUP BY site_id) AS latest
ON latest.site_id = sites.id
LEFT JOIN backups
ON sites.id = backups.site_id
WHERE sites.id = 1
GROUP BY sites.id
ORDER BY backups.initiated_on desc
I have removed the SELECT * as this will only work using MySQL and is generally bad practice anyway. Non-MySQL RDBSs will throw an error if you include the other fields, even individually and you will need to make this query itself into a subquery and then do an INNER JOIN to the sites table to get the rest of the fields. This is because they will be trying to add all of them into the GROUP BY statement and this fails (or is at least very slow) if you have long text fields.