I am working with MySQL and am trying to combine two Subqueries.
It is about time and excluding timespans.
The first (working) query fetches me every single valid day between two dates that are neigther saturday nor sunday (workdays):
SELECT * FROM
(SELECT adddate('1970-01-01',t4.i*10000 + t3.i*1000 + t2.i*100 + t1.i*10 + t0.i) selected_date from
(SELECT 0 i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) t0,
(SELECT 0 i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) t1,
(SELECT 0 i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) t2,
(SELECT 0 i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) t3,
(SELECT 0 i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) t4) v
WHERE selected_date BETWEEN '2021-04-01' and '2021-07-15'
AND weekday(selected_date) <> 5
AND weekday(selected_date) <> 6
The second query fetches me the start and end-Dates of vacations from a table (UNIX-Timestamps) and formats these dates the same way the first query returns them as 2 separate values (from, to):
SELECT date_format(FROM_UNIXTIME(from),'%Y-%m-%d') AS "from", date_format(FROM_UNIXTIME(to),'%Y-%m-%d') AS "to" FROM vacation
I am trying to eliminate every occurence of dates that are within these Timespans between 'from' and 'to' from my second query within my first query.
The thing that gets me is that i dont know how to set multiple BETWEENs dynamically to filter out those ranges. The second query returns multiple 'from' and 'to' values which i want to use as a "NOT BETWEEN-Filter" for my first query.
I hope what i said makes sense to you.
I am glad for every answer pushing me towards the right direction.
Thanks in advance
Felix
Use LEFT JOIN to join the two queries, and then a NULL check to exclude the matched rows.
SELECT t1.*
FROM (first query) AS t1
LEFT JOIN (second query) AS t2 ON t1.selected_date BETWEEN t2.from AND t2.to
WHERE t2.from IS NULL
It would also be better if the second query returned DATETIME values rather than formatted dates, so remove the calls to DATE_FORMAT().
Related
Having a collection of publications, I want to assign a different release date for each one per author. For doing this I am subtracting to all the dates, from publication's date until yesterday, the already taken dates for that author.
The problem of this update is that the current record depends on the assignation of the previous one. Eg: if there is already a feature assigned to April 2nd, new features on that day will be pushed to the 3rd or beyond. But if there are two unassigned features April 2nd, they will be both assigned to the same day.
UPDATE publications pub
SET pub.release_date = (
SELECT all.Dates
FROM ( # This generates all dates between publication date until yesterday
SELECT curdate() - INTERVAL (a.a + (10 * b.a) + (100 * c.a) + (1000 * d.a) ) DAY as Dates
FROM (SELECT 0 as a UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) as a
CROSS JOIN (SELECT 0 as a UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) as b
CROSS JOIN (SELECT 0 as a UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) as c
CROSS JOIN (SELECT 0 as a UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4 UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9) as d
) all
WHERE all.Dates > DATE(pub.date)
AND all.Dates < curdate()
AND all.Dates NOT IN ( # Already taken dates for this author
SELECT DISTINCT(DATE(taken.release_date))
FROM (SELECT * FROM publications) as taken
WHERE taken.author_id = pub.author_id
AND taken.release_date IS NOT NULL
)
ORDER BY Date ASC
limit 1
)
WHERE pub.release_date is null
AND pub.type = 'feature';
I read that the way SQL works (simplifying here) is fetching a dataset to the buffer, altering it and then storing. Guess MySQL does something similar. This mismatch seems to happen because the subquery is not reading from the data buffer that we are updating but from the original dataset.
MySQL doesn't allow PostgreSQL update syntax:
UPDATE ...
SET ...
FROM <-
WHERE ...;
Can a subquery inside a SQL update fetch rows which have just been updated?
I was thinking of subtracting digits one by one but didn't find a way to implement it after a big effort.
Row 1: 100211210
Row 2: 100010220
Result: 000201010
And the result has to be non-negative.
Select SUBSTR(t1.row,1,1)-(t2.row,1, 1)|| SUBSTR(t1.row,2,2)-SUBSTR(t2.row,2, 2)||... so on from table t1 where t1.row NOT IN (Select row in table t2);
This will check in the same table if the row exists then it will skip if not subtract digit by digit or you can use loop in pl/sql by declaring values for substr as i,j for both and then subtracting.
select GROUP_CONCAT(CAST(ABS(substring('123456782',c.count,1)-substring('323456789',c.count,1)) AS CHAR) separator '')
from (select c1.1*10+c2.1 count from (select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9 union all select 0) c1,
(select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9 union all select 0) c2 order by count) c
where c.count>0 and c.count<=length('123456782')
2 string is the same length, and the last parameter is the lenght of the strings
I have a database of employees and their attendance. I have to create the date range reports of attendance.
Attendance Database table
I am using below query
SELECT a.* FROM attendance a WHERE a.user_id=10 AND (a.date BETWEEN '2017-01-06' AND '2017-01-10')
Result:-
I also want records for all given date range but some dates record is not present in database and i want that dates shows null values to corresponds to that dates as shown in below image.
Try this. I am not able to run it but the idea is to generate a date range based on this answer.
Use this date range as derived table d.
Do a d left join attendance adding your condition so you will get all the columns for matching data and null for not matching data.
This will give you rest of the data, except employee id. I suggest you can hardcode it in select query.
select * from
(select a.Date
from
(
select curdate() - INTERVAL (a.a + (10 * b.a) + (100 * c.a)) DAY as Date
from (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as a
cross join (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as b
cross join (select 0 as a union all select 1 union all select 2 union all select 3 union all select 4 union all select 5 union all select 6 union all select 7 union all select 8 union all select 9) as c
) a
where a.Date between '2017-01-06' AND '2017-01-10'
) d
left join
attendance a
on d.date = a.date
where
a.user_id=10
I have a MySQL database named WindData which looks like this:
timestamp
temperature
windspeed
winddirection
I add a new row every 2-3 minutes so over a year time there will be lots of rows.
Now I want to present the data as a chart within a certain timeframe, (4 days ago, last month, last 6 month, 2011-2012...). Say that I want to display how the temperature has varied for the past year, using Google Charts to display this. Then Google chart has a maximum limit of the amount of datapoints that you may use.
I would then like a SQL query where I specify the timerange (2012-01-01 -- 2013-10-10) that gives me
A fixed number of rows (for example 200)
Every row contains the average and max value over that interval.
An ascii art example:
...............1..............2...............+..............199..............200
Where . is one row in my table, and the numbers represent average and maxvalue of the previous dots.
Some psudocode that might show what I am trying to accomplish is:
SELECT AVG(temperature)
FROM WindData
WHERE timestamp > 2012-01-01 AND timestamp < 2013-10-10
This would just give me one result where I get the average value of the whole timerange.
So maybe there is a way to create one more SQL statement which runs the above sql statement 200 times with different time-range.
SELECT AVG(temperature)
FROM WindData
WHERE timestamp > 2012-01-01 AND timestamp < 2013-02-1
SELECT AVG(temperature)
FROM WindData
WHERE timestamp > 2012-02-01 AND timestamp < 2013-03-1
SELECT AVG(temperature)
FROM WindData
WHERE timestamp > 2012-03-01 AND timestamp < 2013-04-1
SELECT AVG(temperature)
FROM WindData
WHERE timestamp > 2012-04-01 AND timestamp < 2013-05-1
...and so on.
If anyone is interested, I will use the help here to present better diagrams on www.surfvind.se, which displays weather data from a homebuilt weather station.
You can get a fixed number of rows using something like this:-
SELECT units.i + tens.i * 10 + hundreds.i AS aNumber
FROM (SELECT 0 AS i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) units
CROSS JOIN (SELECT 0 AS i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) tens
CROSS JOIN (SELECT 0 AS i UNION SELECT 1 ) hundreds
You can use something like this to get the different ranges, and join it against you data to get the number of values within each range.
EDIT - To go with the details you have added:-
SELECT Sub1.aDate, AVG(temperature)
FROM
(
SELECT DATE_ADD('2012-01-01', INTERVAL units.i + tens.i * 10 + hundreds.i * 100 DAY) AS aDate
FROM (SELECT 0 AS i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) units
CROSS JOIN (SELECT 0 AS i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) tens
CROSS JOIN (SELECT 0 AS i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) hundreds
) Sub1
LEFT OUTER JOIN
WindData
ON Sub1.aDate = DATE(WindData.`timestamp`)
GROUP BY Sub1.aDate
This is getting a range of 1000 days starting from 2012-01-01 (you can easily limit that range in the subselect if you want), and matching that against the temp values for a day and getting the average group by date.
I have a table witch has a field with the following record:
1,2,3,4,5,6
I would like to ask the following two things:
1) How can i make a foreign key in another table? The rule would be:
For any value seperated by comma in field `field_name` must be record of other_table.field_id
2) How can i do something like: SELECT explode(field) AS ex FROM table_name ?
the name's of row maybe can retrieve as ex[0]-->1, ex[1]-->2
While it is possible to do a join on a comma separated field (using FIND_IN_SET for example), I don't think there is a way to do this for a foreign key.
MySQL doesn't have an explode function, and your idea would seem to suggest a varying number of columns on each row.
You can split them onto different rows if necessary but it is ugly. And more a good reason to NOT use comma separated fields
SELECT DISTINCT SUBSTRING_INDEX(SUBSTRING_INDEX(field, ',', 1 + units.i + tens.i * 10 + hundreds.i * 100), ',', -1)
FROM table_name
CROSS JOIN (SELECT 0 AS i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) units
CROSS JOIN (SELECT 0 AS i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) tens
CROSS JOIN (SELECT 0 AS i UNION SELECT 1 UNION SELECT 2 UNION SELECT 3 UNION SELECT 4 UNION SELECT 5 UNION SELECT 6 UNION SELECT 7 UNION SELECT 8 UNION SELECT 9) hundreds