I want to manipulate with a table, but the only solution I found so far is to create some tables first and join them together to the desired results.
I'm trying to avoid creating tables and dropping them at the end of my MySQL query which btw, I'm running on phpmyadmin page.
Here is the data: I have one table containing user_id, columnA_unixtime, columnB_unixtime -- meaning that for each user there are two unix_time stored in the database for two different events.
user_id eventA_join eventB_join
1 1321652009 1321652009
2 0 1321652257
3 0 1321668650
4 1321669261 0
what I want to have is a table showing how many users joined the two events for each day. Something like this (just a sample)
day eventA eventB
11/18/11 3 2
11/19/11 11 8
11/20/11 6 3
11/21/11 17 11
Here is the code I'm using so far:
CREATE TABLE table1(
day VARCHAR(256),
eventA_count INT);
INSERT INTO table1 (day, eventA_count)
(SELECT DATE(FROM_UNIXTIME('eventA_join') ) AS 'day', COUNT('user_id') AS 'eventA_count'
FROM org_table
WHERE 'eventA_join' > 0
GROUP BY day);
CREATE TABLE table2(
day VARCHAR(256),
eventB_count INT);
INSERT INTO table2 (day, eventB_count)
(SELECT DATE(FROM_UNIXTIME('eventB_join') ) AS 'day', COUNT('user_id') AS 'eventB_count'
FROM org_table
WHERE 'eventB_join' > 0
GROUP BY day);
SELECT t.day, t1.eventA_count, t2.eventB_count FROM
(SELECT DISTINCT day FROM table1
UNION
SELECT DISTINCT day FROM table2) t
LEFT JOIN table1 t1
ON t.day = t1.day
LEFT JOIN table2 t2
ON t.day = t2.day
DROP table2;
DROP table1;
As far as I tried I couldn't use table variables in phpmyadmin and neither I could use template tables because there was no way to refer to template tables multiple times (error #10327 Can't reopen temporary table) when I try to join them together.
Is there anyway I avoid creating tables but gain what I'm looking for? Any thoughts?
Edit: both tables are getting data from 'org_table' which is now corrected in the code.
This is pretty easy to do with a single query. You just need UNION ALL:
select date, sum(IsEventA) as EventA, sum(isEventB) as EventB
from ((select user_id, DATE(FROM_UNIXTIME('eventA_join') as date,
1 as IsEventA, 0 as IsEventB
from table1
where eventA_join > 0
) union all
(select user_id, DATE(FROM_UNIXTIME('eventB_join') as date,
0 as IsEventA, 1 as IsEventB
from table1
where eventB_join > 0
)
) t
group by date
order by 1
Related
Hello – I have a DB table (MySQL ver 5.6.41-84.1-log) that has about 92,000 entries, with columns for:
id (incremental unique ID)
post_type (not important)
post_id (not important, but shows relation to another table)
user_id (not important)
vote (not important)
ip (IP Address, ie. 123.123.123.123)
voted (Datestamp in GMT, ie. 2018-12-03 04:50:05)
I recently ran a contest and we had a rule that no single IP could vote more than 60 times per day. So now I need to run a custom SQL formula that applies the following rule:
For each IP address, for each day, if there are > 60 rows, delete those additional rows.
Thank you for your help!
This is a complicated one, and I think it is hard to provide a 100% sure answer without actual table and data to play with.
However let me try to describe the logic, and build the query step by step so you can paly around with it and possibly fix lurking erros.
1) We start with selecting all ip adresses that posted more than 60 votes on a given day. For this we use a group by on the voting day and on the ip adress, combined with a having clause
select date(voted), ip_adress
from table
group by date(voted), ip_adress
having count(*) > 60
2) From then, we go back to the table and select the first 60 ids corresponding to each voting day / ip adress couple. id is an autoincremented field so we just sort using this field and the use the mysql limit instruction
select id, ip_adress, date(voted) as day_voted
from table
where ip_adress, date(voted) in (
select date(voted), ip_adress
from table
group by date(voted), ip_adress
having count(*) > 60
)
order by id
limit 60
3) Finally, we go back once again to the table and search for the all ids whose ip adress and day of vote belong to the above list, but whose id is greater than the max id of the list. This is achieved with a join and requires a group by clause.
select t1.id
from
table t1
join (
select id, ip_adress, date(voted) as day_voted
from table
where ip_adress, date(voted) in (
select date(voted), ip_adress
from table
group by date(voted), ip_adress
having count(*) > 60
)
order by id
limit 60
) t2
on t1.ip_adress = t2.ip_adress
and date(t1.voted) = t2.day_voted and t1.id > max(t2.id)
group by t1.id
That should return the list of all ids that we need to delete. Test if before you go further.
4) The very last step is to delete those ids. There are limitations in mysql that make a delete with subquery condition quite uneasy to achieve. See the following SO question for more information on the technical background. You can either use a temporary table to store the selected ids, or try to outsmart mysql by wrapping the subquery and aliasing it. Let us try with the second option :
delete t.* from table t where id in ( select id from (
select t1.id
from
table t1
join (
select id, ip_adress, date(voted) as day_voted
from table
where ip_adress, date(voted) in (
select date(voted), ip_adress
from table
group by date(voted), ip_adress
having count(*) > 60
)
order by id
limit 60
) t2
on t1.ip_adress = t2.ip_adress
and date(t1.voted) = t2.day_voted
and t1.id > max(t2.id)
group by t1.id
) x );
Hope this helps !
You could approach this by vastly simplifying your sample data and using row number simulation for mysql version prior to 8.0 or window function for versions 8.0 or above. I assume you are not on version 8 or above in the following example
drop table if exists t;
create table t(id int auto_increment primary key,ip varchar(2));
insert into t (ip) values
(1),(1),(3),(3),
(2),
(3),(3),(1),(2);
delete t1 from t t1 join
(
select id,rownumber from
(
select t.*,
if(ip <> #p,#r:=1,#r:=#r+1) rownumber,
#p:=ip p
from t
cross join (select #r:=0,#p:=0) r
order by ip,id
)s
where rownumber > 2
) a on a.id = t1.id;
Working in to out the sub query s allocates a row number per ip, sub query a then picks row numbers > 2 and the outer multi-table delete deletes from t joined to a to give
+----+------+
| id | ip |
+----+------+
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 3 |
| 5 | 2 |
| 9 | 2 |
+----+------+
6 rows in set (0.00 sec)
I had someone help me write the following query, which addressed my question.
SET SQL_SAFE_UPDATES = 0;
create table temp( SELECT id, ip, voted
FROM
(SELECT id, ip, voted,
#ip_rank := IF(#current_ip = ip, #ip_rank + 1, 1) AS ip_rank,
#current_ip := ip
FROM `table_name` where ip in (SELECT ip from `table_name` group by date(voted),ip having count(*) >60)
ORDER BY ip, voted desc
) ranked
WHERE ip_rank <= 2);
DELETE FROM `table_name`
WHERE id not in (select id from temp) and ip in (select ip from temp);
drop table temp;
I have a table having id and no field, what I really want is the result raw will be repeated no filed times, if the no field is 2 then that raw must be repeated twice in result.
this is my sample table structure:
id no
1 3
2 2
3 1
now I need to get a result like:
1 3
1 3
1 3
2 2
2 2
3 1
I tried to write mysql query to get the result like above, but failed.
You need a table of numbers to accomplish this. For just three values, this is easy:
select t.id, t.no
from t join
(select 1 as n union all select 2 union all select 3
) n
on t.no <= n.no;
This query must do what you want to achieve:
select t.id, t.no from test t cross join test y where t.id>=y.id
not completely solve your problem, but this one can help
set #i=0;
select
test_table.*
from
test_table
join
(select
#i:=#i+1 as i
from
any_table_with_number_of_rows_greater_than_max_no_of_test_table
where
#i < (select max(no) from test_table)) tmp on no >= i
order by
id desc
EDIT :
This is on SQL Server. I checked online and see that CTEs work on MySQL too. Just couldn't get them to work on SQLFiddle
Try this, remove unwanted columns
create table #temp (id int, no int)
insert into #temp values (1, 2),(2, 3),(3, 5)
select * from #temp
;with cte as
(
select id, no, no-1 nom from #temp
union all
select c.id, c.no, c.nom-1 from cte c inner join #temp t on t.id = c.id and c.nom < t.no and c.nom > 0
)
select * from cte order by 1
drop table #temp
Lets say I have a MySQL table that has the following entries:
1
2
3
2
5
6
7
6
6
8
When I do an "SELECT * ..." I get back all the entries. But I want to get back only these entries, that exist only once within the table. Means the rows with the values 2 (exists two times) and 6 (exists three times) have to be dropped completely out of my result.
I found a keyword DISTINCT but as far as I understood it only avoids entries are shown twice, it does not filters them completely.
I think it can be done somehow with COUNT, but all I tried was not really successful. So what is the correct SQL statement here?
Edit: to clarify that, the result I want to get back is
1
3
5
7
8
You can use COUNT() in combination with a GROUP BY and a HAVING clause like this:
SELECT yourCol
FROM yourTable
GROUP BY yourCol
HAVING COUNT(*) < 2
Example fiddle.
You want to mix GROUP BY and COUNT().
Assuming the column is called 'id' and the table is called 'table', the following statement will work:
SELECT * FROM `table` GROUP BY id HAVING COUNT(id) = 1
This will filter out duplicate results entirely (e.g. it'll take out your 2's and 6's)
Three ways. One with GROUP BY and HAVING:
SELECT columnX
FROM tableX
GROUP BY columnX
HAVING COUNT(*) = 1 ;
one with a correlated NOT EXISTS subquery:
SELECT columnX
FROM tableX AS t
WHERE NOT EXISTS
( SELECT *
FROM tableX AS t2
WHERE t2.columnX = t.columnX
AND t2.pk <> t.pk -- pk is the primary key of the table
) ;
and an improvement on the first way (if you have a primary key pk column and an index on (columnX, pk):
SELECT columnX
FROM tableX
GROUP BY columnX
HAVING MIN(pk) = MAX(pk) ;
select id from foo group by id having count(*) < 2;
I had a problem in database. I have to insert duplicate records of a particular record on a another table based on a value.
First i used cursor to fetch each records and get the number of duplication i wants and after that used another cursor for duplication. Everything worked fine. But if the records in more than 500, i went dead slow. Then i did some research and found a way to insert without cursor.
INSERT INTO report(id, Name)
SELECT i.id,i.Name FROM (SELECT 1 AS id
UNION SELECT 2
UNION SELECT 3
UNION SELECT 4
UNION SELECT 5
UNION SELECT 6
UNION SELECT 7
UNION SELECT 8
UNION SELECT 9
UNION SELECT 10) AS o
INNER JOIN table i WHERE o.id<=i.frequence;
where frequence is the number of duplication. Please drop your idea to improve your query.
You could try creating a table with a record for each value from 1 to 10 and then join to that. I'm not sure it would be any faster though. You would have to experiment with it.
In this example the table with the values from 1 to 10 is called "dup" and the field containing these values is called "id".
INSERT INTO report(id, Name)
SELECT i.id, i.Name
FROM table i
JOIN dup d
ON d.id <= i.frequence;
If you have any table that contains a row number that goes at least as high as the maximum frequence, you could to this:
INSERT INTO report(id, Name)
SELECT i.id,i.Name FROM table i
inner join (
select distinct some_row_number_column from some_table
) o on o.some_row_number_column <= i.frequence;
This is basically the same as what you were doing, but it avoids the messy union all statements.
Or you could make a cursor that inserts numbers from 1 to the maximum frequence into a temporary table, then use that in your join. Or you could use a row numbering variable to generate the necessary sequence. Basically, do anything that will generate a list of consecutive numbers from 1 to the maximum that you need.
I would normally use recursion for this (DB2 syntax):
INSERT INTO report(id, Name)
with num_list (num) as (
values (1)
union all
select num + 1 from num_list
where num < (select max(frequence) from table)
)
SELECT i.id,i.Name FROM table i
inner join num_list on num_list.num <= i.frequence;
However, MySQL doesn't support recursion, apparently.
I have a mysql table with the rows: ID, name, startDate, endDate.
As a rule, the dates should be consecutive and i want to alert the user if an interval is missing.
Saying i have this dates inserted:
2012-03-25 -> 2012-03-29
2012-04-02 -> 2012-04-05
I wanna show a message like
"No dates found from 2012-03-29 to 2012-04-02. Please insert data for this interval"
Can this be done without surfing with php the entire table entries?
Thanks!
SELECT t1.endDate AS gapStart, (SELECT MIN(t3.startDate) FROM `table` t3 WHERE t3.startDate > t1.endDate) AS gapEnd
FROM `table` t1
LEFT JOIN `table` t2
ON t1.endDate = t2.startDate
WHERE t2.startDate IS NULL
This works. I include code for creating table and inserting data for testing purposes.
create table dates(
id int(11) not null auto_increment,
name varchar(16) not null,
startDate date,
endDate date,
primary key(id)
);
insert into dates (name,startDate,endDate)
values('personA', '2012-03-25', '2012-03-29'),
('PersonB','2012-04-02', '2012-04-05');
So here is the query:
select d1.endDate,d2.startDate
from dates d1, dates d2
where (d1.id+1) =d2.id and d1.endDate < d2.startDate;
Yes, it can be done without surfing the whole table using PHP, instead you have to surf the whole table using mysql. A crude solution would be:
SELECT a.enddate AS start_of_gap,
(SELECT MIN(c.startdate)
FROM yourtable c
WHERE c.startdate>a.enddate) AS end_of_gap
FROM yourtable a
WHERE NOT EXISTS (
SELECT 1
FROM yourtable b
WHERE b.startdate=a.enddate + INTERVAL 1 DAY
);
I expect if I thought about it some more, there will be a more efficient (but likely less obvious) method.