I have a simple MySQL query like this:
SELECT * ,
( MATCH (table.get) AGAINST('playstation ' IN BOOLEAN MODE) )
+ ( table.get LIKE '%playstation%') AS _score
FROM table
JOIN users on table.id_user = users.id
WHERE table.expire_datetime > 1375997618
HAVING _score > 0
ORDER BY RAND(table.id) ,_score DESC ;
If I run this query in MySQL, it returns usually more then 1 record, now I would like to LIMIT 1 and get one of them randomly, not always the same record.
Is it possible?
select * from <my_table>
ORDER BY RAND()
LIMIT 4
You would quit seeding the random number generator. My guess is that it is returning the first table id encountered, so the numbers are generated in the same sequence:
SELECT * ,
( MATCH (table.get) AGAINST('playstation ' IN BOOLEAN MODE) )
+ ( table.get LIKE '%playstation%') AS _score
FROM table
JOIN users on table.id_user = users.id
WHERE table.expire_datetime > 1375997618
HAVING _score > 0
ORDER BY RAND()
LIMIT 1;
As I understand problem in ,_score ?
Try this:
Select * FROM (
***your sql query***
) as t
ORDER BY RAND()
LIMIT 1
Related
WITH t as (
SELECT *
FROM scd p
WHERE p.modified_date > FROM_UNIXTIME(1593060230)
AND ( p.main_id = 1
OR FIND_IN_SET(1, p.mult_ids) <> 0 )
ORDER BY modified_date DESC
LIMIT 2 OFFSET 0
),
del as (
SELECT
*
FROM t WHERE (status <> 1 AND status <> 2)
),
w_del as (
SELECT
*
FROM t WHERE (status = 1 OR status = 2)
)
SELECT w_del.*, del.* FROM w_del,del;
How do I achieve this with normal sub queries. I am using MySQL 5.7 and can't use CTEs. Im getting can't reuse table error if I use UNION/sub-queries. Is there a way to achieve this without temporary tables?
Please help.
You can just plug in the code for each alias . . . and keep doing that until you are at the base tables:
SELECT w_del.*, del.*
FROM (SELECT t.*
FROM (SELECT *
FROM scd p
WHERE p.modified_date > FROM_UNIXTIME(1593060230) AND
( p.main_id = 1 OR FIND_IN_SET(1, p.mult_ids) <> 0 )
ORDER BY modified_date DESC
LIMIT 2 OFFSET 0
) t
WHERE (status <> 1 AND status <> 2)
) w_del CROSS JOIN
(SELECT t.*
FROM (SELECT *
FROM scd p
WHERE p.modified_date > FROM_UNIXTIME(1593060230) AND
( p.main_id = 1 OR FIND_IN_SET(1, p.mult_ids) <> 0 )
ORDER BY modified_date DESC
LIMIT 2 OFFSET 0
) t
WHERE (status = 1 OR status = 2)
) del;
One critical point, though: The definition of t is using ORDER BY and LIMIT. If there are ties in the modified_date column, then the two subqueries could return different result sets. You have two choices to avoid a problem here:
Add additional keys to the ORDER BY to ensure that the sorting is stable (i.e. returns the same results each time because the combination of keys is unique).
Materialize the subquery using a temporary table.
For my project, i have a requirement where i have to display all the records in descending order except the first record. I am kind of messed up. Anyways, i have tried the following:
SELECT * FROM ins_nr nl WHERE nl.nl_status = '2' ORDER BY nl.nl_id DESC
Here, i have a table called ins_nr which will display all the records with status 2 and the id which is the primary key(unique). It is displaying in desc order perfectly.
I dont want the first record from the top alone. What should i do? How to modify the above query..?
Use OFFSET. Then you can skip 1 records and select the remaining ones until the end.
Example:
SELECT * FROM ins_nr nl WHERE nl.nl_status = '2'
ORDER BY nl.nl_id DESC LIMIT 99999999999 OFFSET 1;
OR ( You could also use a shorter syntax to achieve the same result: )
$sql = "SELECT * FROM table_name LIMIT 1, 999999999";
You can generate dynamic rownum and filter on it to omit the first row, e.g.:
SELECT *
FROM (
SELECT nl.*, #r := #r + 1 AS `rn`
FROM ins_nr nl, (SELECT #r := 0)
WHERE nl.nl_status = '2'
ORDER BY nl.nl_id DESC
) a
WHERE a.rn > 1;
Another way is to get the max id from subquery and put it in a where clausole
You are looking for the offset clause. This looks like:
SELECT *
FROM ins_nr nl
WHERE nl.nl_status = '2'
ORDER BY nl.nl_id DESC
LIMIT 999999999 OFFET 1;
Unfortunately, LIMIT is required. For this situation, it is traditional to just put in a very large number.
Also, if nl_status is numeric, then use nl.nl_status = 2. Don't compare strings to numbers.
SELECT * FROM (
SELECT * FROM cars WHERE site = '5'
ORDER BY cost DESC LIMIT 0 , 10
)
ORDER BY time
How would I execute a sql query like this? So first it selects the 10 cars with the highest cost, THEN it reorders those 10 cars by what time they were added to the DB.
I tried to figure it out but I just cannot get a grip on the syntax :P
Just give an alias to the sub-query.
SELECT * FROM (
SELECT * FROM `cars` WHERE `site` = '5'
ORDER BY `cost` DESC LIMIT 0 , 10
)t
ORDER BY `time`;
This query will give you the desired results
SELECT * FROM ( SELECT * FROM cars WHERE site = 5
ORDER BY cost DESC LIMIT 0 , 10 ) as t ORDER BY time
What I am trying to get is to send a request to DB that will:
1 count all rows
2 return 10 rows
SELECT count( * ) AS 'total'
FROM stuff
WHERE usr = '65'
LIMIT 10
So it is supposed to return 10 results PLUS 'total' with the number of all rows.
So far it returns the counted amount of rows only....
-- count records first
SET #total = (
SELECT count( * ) AS 'total'
FROM `stuff`
WHERE `usr` = '65'
);
-- then, select your ten records and include the total from previous operation
SELECT *, #total
FROM `stuff`
WHERE `usr` = '65'
LIMIT 10
You'll need to split the 2 concerns out, and then recombine them:
SELECT s.col1, s.col2, s.col3, x.total
FROM `stuff` s
CROSS JOIN
(
SELECT count(*) AS total
FROM `stuff`
WHERE `usr` = '65'
) x
WHERE s.`usr` = '65'
LIMIT 10;
Fiddle here
RDBMs like SqlServer and Oracle allow for CTE's which would allow you to DRY up the repeated select ... where. Some options in MySql here
If you want all rows to be counted and limit the result to 10 then you can do it the following way
SELECT SQL_CALC_FOUND_ROWS * FROM `stuff` WHERE `usr` = '65' LIMIT 10
SELECT FOUND_ROWS();
I am trying to generate a random integer for each row I select between 1 and 60 as timer.
SELECT downloads.date, products.*, (FLOOR(1 + RAND() * 60)) AS timer
I have searched and keep coming up to this FLOOR function as how to select a random integer in a range. This is giving me a 1 for every row.
What am I missing?
I am on mysql 5.0.75
Heres the rest of the query I belive it might be a nesting issue
SELECT *
FROM (
SELECT downloads.date, products.*, FLOOR(1 + (RAND() * 60)) AS randomtimer,
(
SELECT COUNT( * )
FROM distros
WHERE distros.product_id = products.product_id
) AS distro_count,
(SELECT COUNT(*) FROM downloads WHERE downloads.product_id = products.product_id) AS true_downloads
FROM downloads
INNER JOIN products ON downloads.product_id = downloads.product_id
) AS count_table
WHERE count_table.distro_count > 0
AND count_table.active = 1
ORDER BY count_table.randomtimer , count_table.date DESC LIMIT 10
This is working for me. Your mysql version maybe?
SELECT id, (FLOOR( 1 + RAND( ) *60 )) AS timer
FROM users
LIMIT 0 , 30
The output of the RAND function will always be a value between 0 and 1.
Try this:
SELECT downloads.date, products.*, (CAST(RAND() * 60 AS UNSIGNED) + 1) AS timer
Old question, but always actual problem.
Here a way to create a MySQL function random_integer() based on manual :
CREATE FUNCTION random_integer(value_minimum INT, value_maximum INT)
RETURNS INT
COMMENT 'Gets a random integer between value_minimum and value_maximum, bounds included'
RETURN FLOOR(value_minimum + RAND() * (value_maximum - value_minimum + 1));
SELECT ALL random_integer(1, 60) AS timer;
I'm running your query and it does give me a random number for each row.... maybe has something to do with the name of the random (timer)?
You can increase the number multiplied by the number of records in the table.
SELECT id,
(FLOOR( (SELECT MIN(id) FROM your_table ) + RAND( ) * 1000000 ) ) AS timer
FROM your_table
LIMIT 0 , 30