I'm storing some data in a table and I want to be able to display the total data points per day on the graph. So the first graph point might be 7 for Monday, Jan 1, 2013, and then 3 for Tuesday, Jan 2, 2013...etc.
I have full time/date stamps for each of my data points in my table of SQL type datetime.
My pseudo statement looks like this, but I'm concerned since I'm using the datetime data type:
SELECT
DATE(created_at) AS create_date
COUNT(id) AS total
FROM
data_table
GROUP BY
create_date
How can I get the total data points per day, regardless of the timestamp?
Try this
SELECT
DATE(created_at) AS create_date,
COUNT(id) AS total
FROM
data_table
GROUP BY
DATE(created_at)
Best would be to start a daily cron job that stores the number of the data points for every day. So you can every day count the number between let's say 24.00.00 to 23.59.59.
If you want to count them on the fly you might have slow requests on huge data amounts, since the grouping query cannot use table index.
But maybe you can add a new table column where you store just the date additionally to the timestamp.
Related
I'm pretty new to SQL and I'm struggling with one of the questions on my exercise. How would I calculate average session length per daily active user? The table shown is just a sample of what the extended table is. Imagine loads more rows.
I simply used this query to calculate the daily active users:
SELECT COUNT (DISTINCT user_id)
FROM table1
and welcome to StackOverflow!
now, your question:
How would I calculate average session length per daily active user?
you already have the session time, and using AVG function you will get a simple average for all
select AVG(session_length_seconds) avg from table_1
but you want per day... so you need to think as group by day, so how do you get the day? you have a activity_date as a Date entry, it's easy to extract day, month and year from it, for example
select
DAY(activity_date) day,
MONTH((activity_date) month,
YEAR(activity_date) year
from
table_1
will break down the date field in columns you can use...
now, back to your question, it states daily active user, but all you have is sessions, a user could have multiple sessions, so I have no idea, from the context you have shared, how you go about that, and make the avg for each session, makes no sense as data to retrieve, I'll just assume, and serves this answer just to get you started, that you want the avg per day only
knowing how to get the average, let's create a query that has it all together:
select
DAY(activity_date) day,
MONTH((activity_date) month,
YEAR(activity_date) year,
AVG(session_length_seconds) avg
from
table_1
group by
DAY(activity_date),
MONTH((activity_date),
YEAR(activity_date)
will output the average of session_length_seconds per day/month/year
the group by part, you need to have as many fields you have in the select but that do not do any calculation, like sum, count, etc... in our case avg does calculation, so we don't want to group by that value, but we do want to group by the other 3 values, so we have a 3 columns with day, month and year. You can also use concat to join day, month and year into just one string if you prefer...
I have to perform a query on a MySQL database.
I have a table with records, have a column called "date" (the date type), and a column called "time" (type. Integer is stored by multiplying the time of day by 60. eg 8 am is stored as 480).
Unfortunately, the format of this table can not be modified.
My table stores attentions of doctors on call. The doctors on duty working in two shifts: from 8-20, and 20-8.
I need to know the amount of attention for every doctor.
My query must be filtered by date range and shift.
The problem is that, in the case of doctors working at the turn of 20-8, I have to consider a change of day. (sorry for my bad English).
What I have done is this, this would be an example to date of yesterday, and doctors shift 20-8.
SELECT * FROM attentions WHERE (date >= '2015-07-23' and time >=1200) and (date <= '2015-07-24' and time <480)
the query does not work at all.
Supposing the date field is called: 'a_date' with format 'yyyy-mm-ss' and the time field is a number, the query should be:
SELECT * FROM attentions WHERE (date(a_date) >= '2015-07-23' and time >=1200) and (date(a_date) <= '2015-07-24' and time <480)
Can you check using between?
SELECT * FROM attentions WHERE date between '2015-07-23' and '2015-07-24' and time between 1200 and 480
I think you can also use this -
SELECT * FROM ***** where CREATED_DATETIME between '2015-03-12 00:00:00' and '2015-05-11 00:00:00';
I am having trouble understanding the structure of the query i wish to perform. What i have is a large set of data in a table with multiple UnitID's. The units have temperatures and Timestamps of when the temperatures where recorded.
I want to be able to display the data where I can see the Average temperature of each unit separated in a weekly interval.
Apologies for my previous post, I'm still a novice with querying. But i will show you what i have done so far.
SELECT UnitID AS 'Truck ID',
AVG(Temp) As 'AVG Temp',
LogTime AS 'Event Time',
DAY(g.`LogTime`) as 'Day',
MONTH(g.`LogTime`) as 'Month',
COUNT(*) AS 'Count'
FROM `temperature` as g
WHERE DATE_SUB(g.`LogTime`,INTERVAL 1 WEEK)
AND Ana > 13 AND Ana < 16 AND NOT g.Temp = -100
GROUP BY 'truck id', YEAR(g.`LogTime`),MONTH(g.`LogTime`),WEEK(g.`LogTime`)
Order BY 'truck id', YEAR(g.`LogTime`),MONTH(g.`LogTime`),WEEK(g.`LogTime`)
;
(Sorry, I don't know how to display a table result at the moment)
This result gives me the weekly temperature averages of a truck, and shows me on which day of the month the temperature was recorded, as well as a count of temperatures per week, per truck.
The Query I want to perform , creates 5 columns, being UnitID, Week1, Week2, Week3, Week4.
Within the 'Week' columns I want to be able to display a weekly(Every day of the Week) temperature average for each truck, where the following week is set a week after the previous week (ie. Week2 is set to display the avg(temp) one week from Week1).
And this is where I am stuck on the structure of how to create the query. Im not sure if i need to create sub-queries or use a Union clause. I have tried a couple of queries , but i have deleted them because they did not work. I'm not sure if this query is too complex or if its even possible.
If anyone will be able to help I would greatly appreciate it. If there is any other info I can supply that will help, I will try to do so.
Hopefully this is solvable. :p
MySQL has a WEEK function that will return the week of the year as an integer (0-52). You can use that in you GROUP BY clause, and then use the AVG aggregation function to get the average temperature. Your query would look something like this:
SELECT unitID, WEEK(dateColumn) AS week, AVG(tempColumn) AS averageTemperature
FROM myTable
GROUP BY unitID, WEEK(dateColumn);
Here is a list of other helpful Date and Time Functions that may be useful for querying your database.
I have a transaction table and I'm looking to generate a dataset to drive a line chart that shows the sum of all the sales happened on each day during a given period. I have never grouped results like that before and am scratching my head.
Let's say the table is called "transactions", the "datetime" field is called timestamp, and the sales amount on each transaction is "txn_amount". I want the result set to include each day: "1/2/10" and the sum of the transaction amounts.
I need to get a book and spend a week learning mysql... Thanks for helping me out.
select sum(txn_amount) ,timestamp from transactions where timestamp in (select distinct timestamp from transactions) group by timestamp
if datatype is datetime,Use this
select sum(amt) ,substring(dt,1,10) from transactions where substring(dt,1,10) in (select distinct substring(dt,1,10) from transactions) group by substring(dt,1,10)
I have a table containing access logs. I want to know how many accesses to resource_id '123' occured in each hour in a 24 hour day.
My first thought for retrieving this info is just looping through each hour and querying the table in each loop with something like... and time like '$hour:%', given that the time field holds data in the format 15:47:55.
Is there a way I can group by the hours and retrieve each hour and the number of rows within each hour in a single query?
Database is MySQL, language is PHP.
SELECT HOUR(MyDatetimeColumn) AS h, COUNT(*)
FROM MyTable
GROUP BY h;
You can use the function HOUR to get the hour out of the time. Then you should be able to group by that.