Hi i am trying to fetch last 5 minutes of data from oracle table.The query is written below and its not working somehow.
select * from mytable where (time_to_sec(timediff(now(),mytable.time_stamp)) <= 300)
Its showing this error ORA-00904.
I tried one more query.
select * from mytable where TIME_STAMP > (sysdate - numtodsinterval(5,'minute'))
Now, can you tell me the query which fetches data of last 5 minutes and which deletes data that is in the table for more than 12 hours.Thanks.
I need queries in both oracle and mysql. The mysql query i tried is here.
delete from mytable where (time_to_sec(timediff(now(),time_stamp))/3600 >12);
In oracle subtracting 1 from timestamp means one day. And You can substract a fraction of one. So,
current_timestamp - (5/(24*60))
gives You date from 5 minutes ago. Using that we can query:
select * from mytable where TIME_STAMP > current_timestamp - (5/(24*60)
Which should give You needed result. I find this method more straightfoward and simpler to remember than using special functions.
If You want filter out data from last 12 hours than You can query it like this:
select * from mytable where TIME_STAMP <= current_timestamp - 0.5
Related
I have a two tables in a database.
table_1(device_ID, date,voltage)
table_2(device_ID,device_status)
I am trying to create an event to execute every 5 minutes.
What I am trying to achieve is, select device_ID from table_1 if there is no new data over the last 10 minutes and update the table_2, that means set device_status to 0.
How do i pass conditions between two tables?
BEGIN
select device_ID from table_1 where date = DATE_SUB(NOW(), INTERVAL 10 Minutes);
//here i will get device_IDs if there was a data within last 10 minutes.
//but i need device_ID if there were no data.
//how to update table_2 based on the above condition?
END
You can use the results of your first query as a subquery to de-select rows (by using NOT IN) for the UPDATE:
UPDATE table2
SET device_status = 0
WHERE device_ID NOT IN (select device_ID
from table_1
where date > DATE_SUB(NOW(), INTERVAL 10 Minutes))
Note I think you probably want >, not = in your where condition in the subquery.
Some background first. We have a MySQL database with a "live currency" table. We use an API to pull the latest currency values for different currencies, every 5 seconds. The table currently has over 8 million rows.
Structure of the table is as follows:
id (INT 11 PK)
currency (VARCHAR 8)
value (DECIMAL
timestamp (TIMESTAMP)
Now we are trying to use this table to plot the data on a graph. We are going to have various different graphs, e.g: Live, Hourly, Daily, Weekly, Monthly.
I'm having a bit of trouble with the query. Using the Weekly graph as an example, I want to output data from the last 7 days, in 15 minute intervals. So here is how I have attempted it:
SELECT *
FROM currency_data
WHERE ((currency = 'GBP')) AND (timestamp > '2017-09-20 12:29:09')
GROUP BY UNIX_TIMESTAMP(timestamp) DIV (15 * 60)
ORDER BY id DESC
This outputs the data I want, but the query is extremely slow. I have a feeling the GROUP BY clause is the cause.
Also BTW I have switched off the sql mode 'ONLY_FULL_GROUP_BY' as it was forcing me to group by id as well, which was returning incorrect results.
Does anyone know of a better way of doing this query which will reduce the time taken to run the query?
You may want to create summary tables for each of the graphs you want to do.
If your data really is coming every 5 seconds, you can attempt something like:
SELECT *
FROM currency_data cd
WHERE currency = 'GBP' AND
timestamp > '2017-09-20 12:29:09' AND
UNIX_TIMESTAMP(timestamp) MOD (15 * 60) BETWEEN 0 AND 4
ORDER BY id DESC;
For both this query and your original query, you want an index on currency_data(currency, timestamp, id).
I have a table called 'Articles' in that table I have 2 columns that will be essential in creating the query I want to create. The first column is the dateStamp column which is a datetime type column. The second column is the Counter column which is an int(255) column. The Counter column technically holds the views for that particular field.
I am trying to create a query that will generate the last 30 days of records. It will then order the records based on most viewed. This query will only pick up 10 records. The current query I have is this:
SELECT *
FROM Articles
WHERE DATEDIFF(day, dateStamp, getdate()) BETWEEN 0 and 30
LIMIT 10
) TOP10
ORDER BY Counter DESC
This query is not displaying any records, but I don't understand what I am doing wrong. Any suggestions?
The MySQL version of the query would look like this:
SELECT a.*
FROM Articles a
WHERE a.dateStamp >= CURDATE() - interval 30 day
ORDER BY a.counter DESC
LIMIT 10;
Your query is generating an error. You should look at that error before fixing the query.
The query would look different in SQL Server.
I have a MySQL db that stores orders, and has a date field that gets populated when the order reaches a certain point.
I want to create a cron job that checks for all orders where this date is in multiples of 'weeks' ago. For example:
Date stored: 12/1/2012
this row would be returned if the cron job triggered on the following days:
12/8/2012
12/15/2012
12/22/2012
12/29/2012
etc...
How do i structure the MySQL query to fetch data in this way?
You can use modular arithmetic:
SELECT * FROM my_table WHERE DATEDIFF(CURDATE(), my_date) % 7 = 0
I have a table called "actions" with a DATETIME column called "occurred". I'm trying to return the records for today by doing the following
SELECT * FROM `actions` WHERE `occurred` = DATE(NOW());
But I get an empty result set. If I take the WHERE clause out, I can see all 295 rows in the table and there's at least 30 rows from today. Later I will be writing another query to return all records between today's date and X amount of days in the past but before I can get there I need to know why this query is returning an empty result set.
Thanks in advance.
SELECT * FROM actions WHERE DATE(ocurred) = CURDATE();
DATE(ocurred) ignores the time part.
Here's the SQL Fiddle to play with the data: http://www.sqlfiddle.com/#!2/81708/2
If there in no future date in occurred, you could just use below:
SELECT * FROM `actions` WHERE `occurred` > DATE_SUB(CURDATE(), INTERVAL 1 DAY);