hi I'm looking for a way to only show a matching set of mysql results only once. can anyone tell me how to do this?
here's an example of what i'm trying to achieve:
id | profile_id | viewed_profile_id | date_viewed
1 4 7 00:00:00
2 5 6 00:00:00
1 4 7 00:00:00
so if profile_id and viewed_profile_id match then to only show one result for those matching columns rather than twice or three times or however many times it appears in the database?
Use the DISTINCT keyword:
SELECT DISTINCT id, profile_id, viewed_profile_id, date_viewed
FROM myTable
This will show only one row for each unique combination of the columns selected.
Or, reading into your question a lot (since you only want to match profile_id and viewed_profile_id), if you want to show the latest date viewed for each viewer, you can use GROUP BY and select the MAX date viewed. I am also assuming there is data in date_viewed and it is sortable:
SELECT profile_id, viewed_profile_id, MAX(date_viewed)
FROM myTable
GROUP BY profile_id, viewed_profile_id
DISTINCT helps to eliminate duplicates. If a query returns a result that contains duplicate rows, you can remove duplicates to produce a result set in which every row is unique. To do this, include the keyword DISTINCT after SELECT and before the output column list
http://dev.mysql.com/doc/refman/5.0/en/distinct-optimization.html
SELECT DISTINCT(` profile_id`),`viewed_profile_id`,`id`,`date_viewed` FROM `tableName` GROUP BY `viewed_profile_id`
try this:
$query = "SELECT * FROM TABLENAME WHERE profile_id = '$PROFILEIDVALUE' AND viewed_profile_id = '$VIEWEDIDVALUE' LIMIT 0, 1"
Depending upon the ORDER you want use can use ORDER BY id DESC/ASC
I hope this would be useful
Related
Is it possible to sort in MySQL by "order by" using a predefined set of column values (ID) like order by (ID=1,5,4,3) so I would get records 1, 5, 4, 3 in that order out?
UPDATE: Why I need this...
I want my records to change sort randomly every 5 minutes. I have a cron task to update the table to put different, random sort order in it.
There is just one problem! PAGINATION.
I will have visitors who come to my page, and I will give them the first 20 results. They will wait 6 minutes, go to page 2 and have the wrong results as the sort order has already changed.
So I thought that if I put all the IDs into a session on page 2, we get the correct records even if the sorting had already changed.
Is there any other better way to do this?
You can use ORDER BY and FIELD function.
See http://lists.mysql.com/mysql/209784
SELECT * FROM table ORDER BY FIELD(ID,1,5,4,3)
It uses Field() function, Which "Returns the index (position) of str in the str1, str2, str3, ... list. Returns 0 if str is not found" according to the documentation. So actually you sort the result set by the return value of this function which is the index of the field value in the given set.
You should be able to use CASE for this:
ORDER BY CASE id
WHEN 1 THEN 1
WHEN 5 THEN 2
WHEN 4 THEN 3
WHEN 3 THEN 4
ELSE 5
END
On the official documentation for mysql about ORDER BY, someone has posted that you can use FIELD for this matter, like this:
SELECT * FROM table ORDER BY FIELD(id,1,5,4,3)
This is untested code that in theory should work.
SELECT * FROM table ORDER BY id='8' DESC, id='5' DESC, id='4' DESC, id='3' DESC
If I had 10 registries for example, this way the ID 1, 5, 4 and 3 will appears first, the others registries will appears next.
Normal exibition
1
2
3
4
5
6
7
8
9
10
With this way
8
5
4
3
1
2
6
7
9
10
There's another way to solve this. Add a separate table, something like this:
CREATE TABLE `new_order` (
`my_order` BIGINT(20) UNSIGNED NOT NULL,
`my_number` BIGINT(20) NOT NULL,
PRIMARY KEY (`my_order`),
UNIQUE KEY `my_number` (`my_number`)
) ENGINE=INNODB;
This table will now be used to define your own order mechanism.
Add your values in there:
my_order | my_number
---------+----------
1 | 1
2 | 5
3 | 4
4 | 3
...and then modify your SQL statement while joining this new table.
SELECT *
FROM your_table AS T1
INNER JOIN new_order AS T2 on T1.id = T2.my_number
WHERE ....whatever...
ORDER BY T2.my_order;
This solution is slightly more complex than other solutions, but using this you don't have to change your SELECT-statement whenever your order criteriums change - just change the data in the order table.
If you need to order a single id first in the result, use the id.
select id,name
from products
order by case when id=5 then -1 else id end
If you need to start with a sequence of multiple ids, specify a collection, similar to what you would use with an IN statement.
select id,name
from products
order by case when id in (30,20,10) then -1 else id end,id
If you want to order a single id last in the result, use the order by the case. (Eg: you want "other" option in last and all city list show in alphabetical order.)
select id,city
from city
order by case
when id = 2 then city else -1
end, city ASC
If i had 5 city for example, i want to show the city in alphabetical order with "other" option display last in the dropdown then we can use this query.
see example other are showing in my table at second id(id:2) so i am using "when id = 2" in above query.
record in DB table:
Bangalore - id:1
Other - id:2
Mumbai - id:3
Pune - id:4
Ambala - id:5
my output:
Ambala
Bangalore
Mumbai
Pune
Other
SELECT * FROM TABLE ORDER BY (columnname,1,2) ASC OR DESC
I have a database table with the following structure and data:
| username | content | date |
elgrand hello 2013-08-08 17:04:07
alphard hey,how are you elgrand? 2013-08-08 17:50:22
elyson I don't have any idea 2013-08-08 18:14:31
Is it POSSIBLE to select ALL of row where the username is 'elgrand' + ALL of row where the content is containing word 'elgrand'
and the result will be sort by date as DESCENDING ??
I've tried this but seems there is something wrong with the query and wasn't really ORDERED BY the date, and sometimes the result are double.
SELECT * FROM ms_writing
WHERE username='elgrand' OR content LIKE '%elgrand%'
ORDER BY date DESC
You need an AND -
SELECT
*
FROM
ms_writing
WHERE
username = 'elgrand' AND
content LIKE '%elgrand%'
ORDER BY
date DESC
This query will return all rows whose username is elgrand and whose content has the string elgrand.
Please use AND instead OR
SELECT * FROM ms_writing WHERE username='elgrand' AND content LIKE '%elgrand%' ORDER BY date DESC
Results never double until 2 records have same data
You just need to use AND instead of OR. So your query will be:
SELECT * FROM ms_writing
WHERE username='elgrand' AND content LIKE '%elgrand%'
ORDER BY date DESC
Plus one thing for your information, not to use reserve words as a database field name, e.g date,order etc. It might create a sort of ambiguity.
I am trying to select from a database but because the database as duplicate data and the item names in each data may or may not be duplicated. Please look at the example below to understand more
Table shoe
shoeid pid Name
1 1 green
2 1 green
3 2 red
4 3 red
Thats a simple example.
How I can I select Name and pid from this table but i dont want to see any repeated numbers or names. for example i don't want to see red or green or whatever color i have in the database more than once. Please remember I have over 100 colors in the database. The same thing apply to the pid
Use DISTINCT
http://www.mysqltutorial.org/mysql-distinct.aspx
http://www.w3schools.com/sql/sql_distinct.asp
This might be what you want
this gives you only unique results
SELECT DISTINCT Name, pid FROM shoe;
try this:
SELECT DISTINCT Name FROM table_name;
or if you want maximum id in output:
SELECT Name, MAX(pid) AS id FROM table_name GROUP BY Name;
or if you want comma separated list of ids for that Name:
SELECT Name, GROUP_CONCAT(pid) AS id_list FROM table_name GROUP BY Name;
Use GROUP BY
select * from `yourtable` group by `pid`,`Name`
SELECT DISTINCT Name FROM shoe
this query get the unique values , if you want where you can use it by
SELECT DISTINCT Name FROM shoe WHERE your_key = 'your_key_val'
This is an example of my table:
|..id.|.class...|.group....|..name....|
|..5..|....1....|.....A....|....XX....|
|.19..|....1....|.....B....|....XX....|
|.12..|....2....|.....A....|....XX....|
|.28..|....2....|.....B....|....XX....|
|..8..|....3....|.....A....|....XX....|
|.50..|....3....|.....B....|....XX....|
It has about 30 rows per class and group. What I'm trying to do is to fetch all data after the row | 12 | 2 | A | XX |. Can't just state "where class > 2" since there are still some rows with class and group 2A that I need to be in the select.
Is there a way to do that, from SELECT or maybe a Fetch() argument in PHP & Mysql
Thanks!
Try this:
SELECT * FROM `table`
WHERE
CONCAT(`CLASS`, `GROUP`, `NAME`) >= '2AMarcus'
Select all ids and loop through them creating a comma-delimited list in PHP of the ids after 12 is found. Then do your select where id in ().
Or
Create the list of ids to exclude until 12 is found. Then do select where id not in ().
It looks like you need some work on normalizing tables, out of sql sentences.
If you need the rows after Class 2 Group A Name Marcus, it says to me that something occur in real life from that point in the time, an event, so, i would add a new column for timestamp or for another data for that event, and then back to sql sentences and use that new column for the apropiate SELECT / WHERE.
for example i have a table like this :
name rating
matei 124
andrei 20
serj 25
john 190
mike 96
andy 245
tom 73
i need to output something like this(order by rating):
john's position is 2; or, tom's position is 5; (i don't need to get all result , just one )
How can I achieve this?
Thanks in advance
Generally order of rows in a query result is not guaranteed by MySQL unless ordering is explicitly specified with ORDER BY clause. If you have some separate ordering column, you may use query like the following:
SELECT count(1) as position
FROM table
WHERE order_column <= {john's order_column value};
If you don't have ordering column, I'd recommend you to define first, what does "john's position" and "tom's position" mean.
UPDATE:
AFAIU, you want to get position in list sorted by rating (sorry, I initially did not get it). So, rating would be your order_column. In this case, you should decide, how do you calculate position, if two guys have equal rating (who's position is higher?).
So, the query may look in the following way:
SELECT count(1) as position
FROM table
WHERE
rating > (SELECT rating FROM table WHERE id={user's ID});
SELECT COUNT(*) + 1
FROM users
WHERE (rating, name) <
(
SELECT rating, name
FROM users
WHERE name = 'john'
)
Note that if you will have duplicates on both name and rating, this query will assign the same rating to both of them.
Tables are more formally known as relations in database literature - they are not guaranteed to be ordered (they are sets of "tuples"), so your question doesn't make sense. If you need to rely on an order/position, you need to define an additional column (like an auto-incrementing ID column) to capture and store that info.
Is this any help > http://craftycodeblog.com/2010/09/13/rownum-simulation-with-mysql/ ?
Would offset not work like so?
SELECT * FROM Table ORDER BY rating DESC LIMIT 1,6
This would return 1 row that has been off setted by 6 rows ? or am I mistaken, the syntax would be
SELECT * FROM Table ORDER BY rating DESC LIMIT 1 , {{POS}}