I have the following table with measured values:
datetime | water | air | conductivity | ...
2021-07-17 16:44:39 | 13,9 | 18,6 | 357 | ...
I am currently querying the values for a period of time:
SELECT * FROM kn1 WHERE datetime > TIMESTAMP(DATE_SUB(NOW(), INTERVAL 1 month)) ORDER BY datetime
Now I don't want to get every value, just the highest value of each day.
In general, I can query the highest value through
SELECT MAX(water) FROM kn1 WHERE datetime > TIMESTAMP(DATE_SUB(NOW(), INTERVAL 1 month)) ORDER BY datetime
But this way I get the highest value for the entire period. But I would like to get the highest value for each day in the period.
How can I do this?
Thanks in advance
Use GROUP BY:
SELECT DATE(datetime), MAX(water)
FROM kn1
WHERE datetime > CURDATE() - INTERVAL 1 month)
GROUP BY DATE(datetime);
Note that I modified the WHERE clause to simplify it. Presumably, you don't date about the current time, just the date, so this uses the current date. Second, there is no need for TIMESTAMP, and third, I find interval arithmetic to be simpler without additional functions.
Related
I am seeking to find first date of the month in the corresponding table:
So if i have 26/08/2011 August as date and 2 months to add, it becomes 26/10/2011. I need the first date of the resulting month- like 01/10/2011.
Can this be achieved in SQL?
Update : I could get the date of the month using
DATEADD(month,months_add, date)
Couldnt get to "beginning of month". Tried: How can I select the first day of a month in SQL?
But for me it throws the error: function pg_catalog.date_diff("unknown", integer, date) does not exist;
You could try using date_add for add two months and date_sub for sub the days -1
set #my_date = "2017-06-15";
SELECT DATE_SUB( DATE_ADD(#my_date, INTERVAL 2 MONTH),
INTERVAL DAYOFMONTH(#my_date)-1 DAY);
SELECT table.date,
table.month_add,
DATE_FORMAT(table.date + INTERVAL table.month_add MONTH,
'%Y-%m-01') AS beginning_of_month
FROM table
Assuming your date is currently a varchar in dd/MM/yyyy format, you can use STR_TO_DATE to convert it to a DATE type column, then use DATE_ADD with your months_add column to dynamically add months then finally use DATE_FORMAT to display it back in a 01/MM/yyyy format with the first day of the month.
SELECT
Date_Column,
Date_Months_Add,
DATE_FORMAT(DATE_ADD(STR_TO_DATE(Date_Column, "%d/%m/%Y" ), INTERVAL Date_Months_Add MONTH), '01/%m/%Y') AS Date_Beginning
FROM sample
Result:
| Date_Column | Date_Months_Add | Date_Beginning |
|-------------|-----------------|-----------------|
| 26/08/2011 | 2 | 01/10/2011 |
| 25/04/2011 | 1 | 01/05/2011 |
| 16/09/2022 | 3 | 01/12/2022 |
| 14/07/2022 | 4 | 01/11/2022 |
Fiddle here.
I have a table with data like the tableA example below. the date column is formatted as a string.
the close column is an integer, ticker is formatted as string.
I'm trying to run the query below on a mysql database and it is taking a very long time.
is there anything I can do to speed this up, like changing the format of the date column, or adding
indices or primary keys? The combination of ticker and date should be a unique value, and the date field is a timestamp, it's just currently formatted as string.
code:
select avg((a.close-b.close)/b.close) as avg_annual_returns,
a.ticker
from tableA a
join tableA b
on cast(a.date as date)=date_add(cast(b.date as date),interval 365 DAY)
and a.ticker=b.ticker
where b.close is not null
group by a.ticker
tableA
+--------+-----+------+
|date |close|ticker|
+--------+-----+------+
|2/1/2019|5 |abc |
+--------+-----+------+
|2/3/2019|7 |efd |
+--------+-----+------+
|2/4/2019|3 |hij |
+--------+-----+------+
update answer:
select ticker,date, ( -1 +
a.close / max(a.close) over (partition by ticker
order by date
range between interval 365 day preceding and interval 365 day preceding
)
) as annual_returns
from tableA a
) b where annual_returns is not null
group by ticker
If you want the difference from a year ago, then use window functions. Before that, though, fix the data model! Do not store dates as strings. So:
alter table talbeA modify column date date;
Then to get the close from a year ago:
select( -1 +
a.close / max(a.close) over (partition by ticker
order by date
range between interval 365 day preceding and interval 365 day preceding
)
)
from tablea a;
You don't have to worry about NULL values because AVG() ignores them.
Here is a db<>fiddle.
The problem is here:
on cast(a.date as date)=date_add(cast(b.date as date),interval 365 DAY)
Both sides of that are not "sargeable", so it can't use any index.
Assuming date is datatype DATE, then this works:
ON a.date = b.date - INTERVAL 1 YEAR
Also, have
INDEX(ticker, date) -- in this order.
Note: 1 YEAR will hiccup around Feb 28; 365 DAY will hiccup for 366 days ever 4 years.
Also, change
where b.close is not null
to
WHERE b.ticker IS NOT NULL
(Functionally they are the same, but I picked a column in the index, just in case it matters.) Well, OK, are there any rows where close is NULL?
Oh, another issue. Because of weekends, only 3 or 4 days of each week can find a matching day in the previous year.
I am building out a query to search a table by a timestamp column value. An example of the format I am passing to the api is 2018-10-10. The user has the ability to select a date range. Often times the date range start date is 2018-10-10 and end date is the same day, 2018-10-10. The below doesn't seem to do the trick. What is the simplest way to accomplish this without having to specify the time? Obviously, I'd like to query for the entire day of 2018-10-10 from start to end of day.
SELECT
count(*)
FROM
contact
WHERE
created_at >= '2018-10-10'
AND created_at <= '2018-10-10';
The problem here is that Timestamp datatype will have HH:MM:SS (time) values also. While comparing a datetime with date, MySQL would automatically assume 00:00:00 as HH:MM:SS for the date value.
So, 2018-10-10 12:23:22 will not match the following condition: created_at <= '2018-10-10'; since it would be treated as: 2018-10-10 12:23:22 <= '2018-10-10 00:00:00, which is false
To handle this, you can add one day to the date (date_to in the filter), and use < operator for range checking.
SELECT
count(*)
FROM
contact
WHERE
created_at >= '2018-10-10'
AND created_at < ('2018-10-10' + INTERVAL 1 DAY);
id start_date interval period
1 1/22/2018 2 month
2 2/25/2018 3 week
3 11/24/2017 3 day
4 7/22/2017 1 year
5 2/25/2018 2 week
the above is my table data sample. start_dates will be expired based on interval and period(i.e id-1 will have due date after 2 months from the start_date, id-2 will have due after 3 weeks vice versa). period is enum of (day,week,month,year). Client can give any period of dates. let's say 25-06-2026 to 13-07-2026 like that.. I have to return the ids whose due dates falls under that period.I hope i made my question clear.
Here what i have done to resolve this. I am using mysql 5.7. I found ways to achieve this with recursive CTE's.(not available in mysql 5.7). and there is a way to achieve this by populating virtual records by using inline sub queries along with unions and its a performance killer and there is restriction of population of records.(like given in the link Generating a series of dates) I have reached a point to get results for a single date which is very easy. Below is my query(in oracle)
select id
from (select a.*,
case
when period='week'
then mod((to_date('22-07-2018','dd-mm-yyyy')-start_date),7*interval)
when period='month' and to_char(to_date('22-07-2018','dd-mm-yyyy'),'dd')=to_char(start_date,'dd')
and mod(months_between(to_date('22-07-2018','dd-mm-yyyy'),start_date),interval)=0
then 0
when period='year' and to_char(to_date('22-07-2018','dd-mm-yyyy'),'dd-mm')=to_char(start_date,'dd-mm')
and mod(months_between(to_date('22-07-2018','dd-mm-yyyy'),start_date)/12,interval)=0
then 0
when period='day'
and mod((to_date('22-07-2018','dd-mm-yyyy')-start_date),interval)=0
then 0 else 1 end filter from kml_subs a)
where filter=0;
But I need to do this for a period of dates not a single date. Any suggestions or solutions will be much appreciated.
Thanks,
Kannan
Assuming this is an Oracle question and not MySQL:
I think the first thing that you need to do is calculate when the due date is. I think a simple case statement can handle that for you:
case when period = 'day' then start_date + numtodsinterval(interval,period)
when period = 'week' then start_date + numtodsinterval(interval*7,'day')
when period = 'month' then add_months(start_date,interval)
when period = 'year' then add_months(start_date,interval*12)
end due_date
Then, using that new due_date field, you can check if the due date falls between the desired date range.
select *
from(
select id,
start_date,
interval,
period,
case when period = 'day' then start_date + numtodsinterval(interval,period)
when period = 'week' then start_date + numtodsinterval(interval*7,'day')
when period = 'month' then add_months(start_date,interval)
when period = 'year' then add_months(start_date,interval*12)
else null end due_date
from data)
where due_date between date '2018-02-25' and date '2018-03-12'
The above query checking between 2/25/18 and 3/12/18 produces the following output using your data:
+----+-------------+----------+--------+-------------+
| id | start_date | interval | period | due_date |
+----+-------------+----------+--------+-------------+
| 2 | 05-FEB-2018 | 3 | week | 26-FEB-2018 |
| 5 | 25-FEB-2018 | 2 | week | 11-MAR-2018 |
+----+-------------+----------+--------+-------------+
Hello i need expert advice for my mysql query
I'm trying to filter values between 2 months
If start day lower then end day of different months all working well
But if i try higher day value on start return none
this is working code
SELECT id, teslim_tarihi AS tarih, toplam, marka, model, malzeme
FROM ariza
WHERE durum = '7' AND (teslim_tarihi BETWEEN '01-02-2018 00:00' AND '01-03-2018 23:59')
ORDER BY tarih DESC
Not working at all
SELECT id,teslim_tarihi as tarih ,toplam,marka,model,malzeme
FROM ariza
WHERE durum = '7' AND (teslim_tarihi BETWEEN '14-02-2018 00:00' AND '01-03-2018 23:59')
ORDER BY tarih DESC
date format dd-mm-yyyy H:i
As has been suggested by #stackFan, it really does make considerable sense to stick with mysql's default date and time formats. However, for whatever reason, you seem to be stuck with a different format so I'll attempt to work with that.
Your current query isn't working in your second example because mysql doesn't recognise these as dates and a strings starting '14-02-2018' is greater than another string starting '01-03-2018'. e.g.
SELECT '14-02-2018' > '01-03-2018';
+-----------------------------+
| '14-02-2018' > '01-03-2018' |
+-----------------------------+
| 1 |
+-----------------------------+
The values when using BETWEEN ... AND have to have the min value first and the max value Documentation, so in your second example the comparison is the wrong way round because '14-02-2018' is greater than '01-03-2018', hence no rows returned.
You didn't answer the query about the data type of your column teslim_tarihi which would have made answering your query simpler. I'll assume it is a DATETIME or TIMESTAMP. Your comparison should be made against something that mysql knows to be a date or recognises as a date and that means getting the dates into YYYY-MM-DD or YY-MM-DD format. Mysql will helpfully cast values to the appropriate type if the format is one it recognises. e.g.
SELECT DATE '2018-02-14' < '2018-03-01';
+-----------------------------------+
| DATE '2018-02-14' < '2018-03-01' |
+-----------------------------------+
| 1 |
+-----------------------------------+
You should be able to get the query working by turning your strings into dates in the following manner.
SELECT DATE '2018-03-01'
BETWEEN STR_TO_DATE('14-02-2018 00:00', '%d-%m-%Y %H:%i')
AND STR_TO_DATE('01-04-2018 23:59','%d-%m-%Y %H:%i') 'between dates';
+---------------+
| between dates |
+---------------+
| 1 |
+---------------+
If your column teslim_tarihi is a VARCHAR, then convert that in the same manner to get the query to work.
As per the documentation the default format of date in MySQL is YYYY-MM-DD. Can you try using this query instead?
SELECT id,teslim_tarihi as tarih ,toplam,marka,model,malzeme
FROM ariza
WHERE durum = '7' AND (teslim_tarihi BETWEEN '2018-02-14 00:00:00' AND '2018-03-01 23:59:59')
ORDER BY tarih DESC