I am new to stored procedure
select distinct(movie_id) from movielist where mdate = ?
This return movie_id(s) and I need to run 3 sql for each movie_id
foreach(movie_id){
select count(*) as total_viewed from movielist where mdate = ? and movie_id = ? limit 1 //return only one value
select count(*) as total_viewed from movielist where mdate like ? and movie_id = ? limit 1 //return only one value
select count(*) as total_viewed from movielist where mdate like ? and movie_id = ? limit 1 //return only one value
//Then all the 3 value with movie_id and mdate insert at another table
}
Now how to write the stored procedures for this...
I guess you want to show the number of views based on each movie
select count(*) as total_viewed from movielist group by movie_id
this will show you all the counts based on movie_id
select count(*) as total_viewed from movielist group by mdate,movie_id
will show you all counts based on date and movie..
You can use UNION ALL to merge the results (just a hint, can be used, don't know what do you actually want).
You could use a cursor, but you do not need at all.
I am not sure what your stored procedure should do, but looks like to give the top 3 viewed movies on a particular day? If so just do
select movie_id, count(*) as total_viewed from movielist
where mdate = ?
group by movie_id
order by total_viewed desc
limit 0,3;
Related
I have a table. Table has structure of id, name, color, product_id.
And the table has multiple rows with the same product_id.
With SQL query from PHP file - I would like to choose only one, the oldest, row. (The first one that was added to the current table).
What query should I use or approach?
Thank you!
Just making up a bit of mockup data ... Note the notes I put in. And I trust it's a newer version of MySQL, as the older ones did not support ROW_NUMBER() OVER() .
Here goes:
WITH
-- input ... you *need* a timestamp to identify the oldest ---
indata(id, name, color, product_id,ts) AS (
SELECT 1,'Arthur','blue' ,42,TIMESTAMP'2021-01-31 17:45:00'
UNION ALL SELECT 1,'Arthur','blue' ,42,TIMESTAMP'2021-01-31 17:50:00'
UNION ALL SELECT 1,'Arthur','blue' ,42,TIMESTAMP'2021-01-31 17:55:00'
UNION ALL SELECT 1,'Arthur','blue' ,42,TIMESTAMP'2021-01-31 18:00:00'
UNION ALL SELECT 2,'Ford' ,'red' ,42,TIMESTAMP'2021-01-31 17:45:00'
UNION ALL SELECT 2,'Ford' ,'blue', 42,TIMESTAMP'2021-01-31 17:50:00'
UNION ALL SELECT 2,'Ford' ,'green',42,TIMESTAMP'2021-01-31 17:55:00'
UNION ALL SELECT 2,'Ford' ,'cyan' ,42,TIMESTAMP'2021-01-31 18:00:00'
)
,
-- select all, plus a rank, on which you will filter outside ..
with_rank AS (
SELECT
*
, ROW_NUMBER() OVER(PARTITION BY id ORDER BY ts) AS rnk
FROM indata
)
SELECT
id
, name
, color
, product_id
, ts
FROM with_rank
WHERE rnk = 1
id|name |color|product_id|ts
1|Arthur|blue |42 |2021-01-31 17:45:00
2|Ford |red |42 |2021-01-31 17:45:00
One method is a correlated subquery:
select t.*
from t
where t.id = (select min(t2.id)
from t t2
where t2.product_id = t.product_id
);
This assumes that id is incrementing with each insertion. If not, you have no way of knowing what the "oldest" row is. SQL tables represent unordered sets, so there is no "oldest" row unless a column contains that information.
SELECT * FROM TableName WHERE product_id = ProductID ORDER BY product_id LIMIT 1;
I would like to get number of all records and get last record :
$sql_count_sms = "SELECT count(*) as total,content,id FROM android_users_sms WHERE user_id=$id ORDER BY id DESC";
$result_count_sms = mysql_query($sql_count_sms);
$row_num_sms = mysql_fetch_assoc($result_count_sms);
$num_sms = $row_num_sms['total'];
$last_my_sms = $row_num_sms['content'];
I can get number of records but I can't get last content record .
It returns first record !
Where is my wrong ?
Below codes works fine, but I think count(*) is faster than mysql_num_rows .
$sql_count_sms = "SELECT content,id FROM android_users_sms WHERE user_id=$id ORDER BY id DESC";
$result_count_sms = mysql_query($sql_count_sms);
$row_num_sms = mysql_fetch_assoc($result_count_sms);
$num_sms = mysql_num_rows($result_count_sms);
$last_my_sms = $row_num_sms['content'];
Any solution?
The grain of the two results you want is not the same. Without using a sub-query you can't combine an aggregate and a single row into the same result.
Think of the grain as the base unit of the result. The use of GROUP BY and aggregate functions can influence that "grain"... one result row per row on table, or is it grouped by user_id etc... Think of an aggregate function as a form of grouping.
You could break it out into two separate statements:
SELECT count(*) as total FROM android_users_sms WHERE user_id = :id;
SELECT * FROM android_users_sms WHERE user_id = :id ORDER BY id DESC LIMIT 1;
Also, specific to your question, you probably want a LIMIT 1 in combination with the ORDER BY to get just the last row.
Now, counter intuitively perhaps, this should also work:
SELECT count(*), content, id
FROM android_users_sms
WHERE user_id = :id
GROUP BY id, content
ORDER BY id
LIMIT 1;`
This is because we've changed the "grain" with the GROUP BY. This is the real nuance and I feel like this could probably be explained better than I am doing now.
You could also do this with a sub query like so:
SELECT aus.*,
(SELECT count(*) as total FROM android_users_sms WHERE user_id = :id) AS s1
FROM android_users_sms AS aus
WHERE user_id = :id ORDER BY id DESC LIMIT 1;
I have a table with named "user-recent-activity" which has following columns: id, userid, activity and datetime. Now, I want to delete the records if any unique userid has more than 50 items, deleting the oldest records. For example, if the user id(lets say 1234) has more than 50 records in this table, then I have to save latest 50 records of user id(1234) and delete the oldest one.
Before inserting, query for the last 50 records with that ID (ordering from newer to older). If there is a 50th, substitute it (via update) instead of inserting a new row.
Assuming you are using a RDBMS that supports standard SQL the following stored procedure should do it.
create procedure remove-old-activities
(
#userid int
)
as
delete from user-recent-activity where userid=#userid and id not in (select top 50 id from user-recent-activity where userid=#userid order by datetime desc)
If you're DB does not support stored procedures then you should be able to use SQL parameters to pass the userid value...
Hope that helps
You could use rank method to precisely defined the rows number and thus delete the rows you want.
delete from tblName where id=
(select id from (
select #i := CASE WHEN ( #userid <> userid ) THEN 1
ELSE #i+1
END AS rank , id,userid, datetime2 ,#userid:=userid AS clset
from tblName x,(SELECT #i:=0) a ,(SELECT #userid:= 0) s
order by x.userid, datetime2 desc) T
where T.rank='50') ;
Another option:
Use the select query to select the rank <=50 and insert into a new table. Delete the old table and rename the new table afterwards.
insert into newtable (userid,activity,datetime2)
select userid,datetime2 from (
select #i := CASE WHEN ( #userid <> userid ) THEN 1
ELSE
#i+1
END AS rank , userid, activity,datetime2 ,#userid:=userid AS clset
from tblName x,(SELECT #i:=0) a ,(SELECT #userid:= 0) s
order by x.userid, datetime2 desc) T
where t.rank <=50
so I'm trying to create a ranking system for my website, however as a lot of the records have same number of points, they all have same rank, is there a way to avoid this?
currently have
$conn = $db->query("SELECT COUNT( * ) +1 AS 'position' FROM tv WHERE points > ( SELECT points FROM tv WHERE id ={$data['id']} )");
$d = $db->fetch_array($conn);
echo $d['position'];
And DB structure
`id` int(11) NOT NULL,
`name` varchar(150) NOT NULL,
`points` int(11) NOT NULL,
Edited below,
What I'm doing right now is getting records by lets say
SELECT * FROM tv WHERE type = 1
Now I run a while loop, and I need to make myself a function that will get the rank, but it would make sure that the ranks aren't duplicate
How would I go about making a ranking system that doesn't have same ranking for two records? lets say if the points count is the same, it would order them by ID and get their position? or something like that? Thank you!
If you are using MS SQL Server 2008R2, you can use the RANK function.
http://msdn.microsoft.com/en-us/library/ms176102.aspx
If you are using MySQL, you can look at one of the below options:
http://thinkdiff.net/mysql/how-to-get-rank-using-mysql-query/
http://www.fromdual.ch/ranking-mysql-results
select #rnk:=#rnk+1 as rnk,id,name,points
from table,(select #rnk:=0) as r order by points desc,id
You want to use ORDER BY. Applying on multiple columns is as simple as comma delimiting them: ORDER BY points, id DESC will sort by points and if the points are the same, it will sort by id.
Here's your SELECT query:
SELECT * FROM tv WHERE points > ( SELECT points FROM tv WHERE id ={$data['id']} ) ORDER BY points, id DESC
Documentation to support this: http://dev.mysql.com/doc/refman/5.0/en/sorting-rows.html
Many Database vendors have added special functions to their products to do this, but you can also do it with straight SQL:
Select *, 1 +
(Select Count(*) From myTable
Where ColName < t.ColName) Rank
From MyTable t
or to avoid giving records with the same value of colName the same rank, (This requires a key)
Select *, 1 +
(Select Count(Distinct KeyCol)
From myTable
Where ColName < t.ColName or
(ColName = t.ColName And KeyCol < t.KeyCol)) Rank
From MyTable t
UPDATE statistics'
SET money = money + '$money'
WHERE member_id IN ((SELECT member_id FROM races WHERE l_id = '$mem_id'), $other_id)
What's wrong with that? I want to retrieve all member_ids from races and also include to member_id $other_id. Without $other_id it works.
By the way, it gives me "Subquery returns more than 1 row" error.
Try with:
UPDATE statistics
SET money = money + $money
WHERE member_id IN (
SELECT member_id
FROM races
WHERE l_id = $mem_id
)
OR member_id = $other_id
And suggestion - for int type columns do not use apostrophs.
subquery returns member_id and $other_id
Another way to do it:
(SELECT member_id FROM races WHERE l_id = '$mem_id'
UNION
SELECT $other_id)