How would I go about doing a query that returns results of all rows that contain dates for current year and month at the time of query.
Timestamps for each row are formated as such: yyyy-mm-dd
I know it probably has something to do with the date function and that I must somehow set a special parameter to make it spit out like such: yyyy-mm-%%.
Setting days to be wild card character would do the trick but I can't seem to figure it out how to do it.
Here is a link to for quick reference to date-time functions in mysql:
http://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.html
Thanks
I think EXTRACT is the function you are looking for:
SELECT * FROM table
WHERE EXTRACT(YEAR_MONTH FROM timestamp_field) = EXTRACT(YEAR_MONTH FROM NOW())
you could extract the year and month using a function, but that will not be able to use an index.
if you want scalable performance, you need to do this:
SELECT *
FROM myTable
WHERE some_date_column BETWEEN '2009-01-01' AND '2009-01-31'
select * from someTable where year(myDt) = 2009 and month(myDt) = 9 and day(myDt) = 12
Related
I am merging 2 huge tables in Snowflake and I have 2 columns (one on each table):
"Year_birth" and "Exam_date" and the info inside looks like this respectively:
"1918" and "2007-03-13" (NUMBER(38,0) and VARCHAR(256))
I only want to merge the rows where the difference (i.e., age when the exam was made) is ">18" and "<60"
I was playing around with SELECT DATEDIFF(year,Exam_date, Year_birth) with no success.
Any ideas on how would I do it in Snowflake?
Cheers!
You only have a year, so there is not much you can do about the specific day of the year -- you need to deal with approximations.
So, extract the year from the date string (arggh! it should really be a date) and just compare them:
where (left(datestr, 4)::int - yearnum) not between 18 and 60
I would strongly advise you to fix the database and store these values using a proper date datatype.
You will need to convert the integer year into a date before doing a datediff
example:
set YearOfBirth = 1918;
set ExamDate = '2007-03-03'::DATE;
-- select $YearofBirth as YearofBirth, $ExamDate as ExamDate;
select $YearofBirth as YearofBirth,($YearofBirth::TEXT||'-01-01')::DATE as YearofBirthDate, $ExamDate as ExamDate, datediff(year,($YearofBirth::TEXT||'-01-01')::DATE,$ExamDate) as YearsSinceExam;
USE YEARS_DIFF IN WHERE CLAUSE TO FILTER DIFFERENCE BETWEEN 18 & 60
SELECT DATEDIFF( YEAR,'2007-03-03',TO_DATE(2018::CHAR(4),'YYYY')) YEARS_DIFF;
So this my table structure and data.
Now I want to filter data based on Month by ExpenseDate column.
So how can I achieve that?
I was trying
select * from tblExpenses where (ExpenseDate = MONTH('April'))
But it throws an error: "Conversion failed when converting date and/or time from character string."
Please help. Thank you.
You are putting month() on the wrong column. It can be applied to ExpensesDate:
select *
from tblExpenses
where month(ExpenseDate) = 4;
Note that month() returns a number, not the name of the month.
I think it is more likely that you want records from a particular April, not every April. This would be expressed as:
where ExpenseDate >= '2018-04-01' and ExpenseDate < '2018-05-01'
I think your where clause is just reversed I think you want this (and change the word to a number)
select * from tblExpenses where Month(ExpenseDate) = 4
Suppose I have the following query:
select customer_name, origination_date
where origination_date < '01-DEC-2013';
I would like to select all customers that have an origination date older than 30 days. Is there a way in SQL (oracle, if specifics needed) to specify it in a more dynamic approach than manually entering the date so that I don't need to update the query every time I run it?
Thanks!
Sure try something like this:
select customer_name, origination_date where
origination_date >= DATEADD(day, -30, GETUTCDATE());
This basically says where the origination_date is greater or equal to 30 days from now. This works in Microsoft SQL, not sure but there is probably a similar function on Oracle.
in Oracle, when you subtract dates, by default you get the difference in days, e.g.
select * from my_table where (date_1 - date_2) > 30
should return the records whose date difference is greater than 30 days.
To make your query dynamic, you parameterize it, so instead of using hard coded date values, you use:
select * from my_table where (:date_1 - :date_2) > :threshold
If you are using oracle sql developer to run such a query, it will pop up a window for you to specify the values for your paramteres; the ones preceded with colon.
I have a table with a date column where date is stored in this format:
2012-08-01 16:39:17.601455+0530
How do I group or group_and_count on this column by month?
Your biggest problem is that SQLite won't directly recognize your dates as dates.
CREATE TABLE YOURTABLE (DateColumn date);
INSERT INTO "YOURTABLE" VALUES('2012-01-01');
INSERT INTO "YOURTABLE" VALUES('2012-08-01 16:39:17.601455+0530');
If you try to use strftime() to get the month . . .
sqlite> select strftime('%m', DateColumn) from yourtable;
01
. . . it picks up the month from the first row, but not from the second.
If you can reformat your existing data as valid timestamps (as far a SQLite is concerned), you can use this relatively simple query to group by year and month. (You almost certainly don't want to group by month alone.)
select strftime('%Y-%m', DateColumn) yr_mon, count(*) num_dates
from yourtable
group by yr_mon;
If you can't do that, you'll need to do some string parsing. Here's the simplest expression of this idea.
select substr(DateColumn, 1, 7) yr_mon, count(*) num_dates
from yourtable
group by yr_mon;
But that might not quite work for you. Since you have timezone information, it's sure to change the month for some values. To get a fully general solution, I think you'll need to correct for timezone, extract the year and month, and so on. The simpler approach would be to look hard at this data, declare "I'm not interested in accounting for those edge cases", and use the simpler query immediately above.
It took me a while to find the correct expression using Sequel. What I did was this:
Assuming a table like:
CREATE TABLE acct (date_time datetime, reward integer)
Then you can access the aggregated data as follows:
ds = DS[:acct]
ds.select_group(Sequel.function(:strftime, '%Y-%m', :date_time))
.select_append{sum(:reward)}.each do |row|
p row
end
How best store year, month, and day in a MySQL database so that it would be easily retrieved by year, by year-month, by year-month-day combinations?
Let's say you have a table tbl with a column d of type DATE.
All records in 1997:
SELECT * FROM tbl WHERE YEAR(d) = 1997
SELECT * FROM tbl WHERE d BETWEEN '1997-01-01' AND '1997-12-31'
All records in March of 1997:
SELECT * FROM tbl WHERE YEAR(d) = 1997 AND MONTH(d) = 3
SELECT * FROM tbl WHERE d BETWEEN '1997-03-01' AND '1997-03-31'
All records on March 10, 1997:
SELECT * FROM tbl WHERE d = '1997-03-10'
Unless a time will ever be involved, use the DATE data type. You can use functions from there to select portions of the date.
I'd recommend the obvious: use a DATE.
It stores year-month-day with no time (hour-minutes-seconds-etc) component.
Store as date and use built in functions:day(), month() or year() to return the combination you wish.
What's wrong with DATE? As long as you need Y, Y-M, or Y-M-D searches, they should be indexable. The problem with DATE would be if you want all December records across several years, for instance.
This may be related to the problem that archivists have with common date datatypes. Often, you want to be able to encode just the year, or just the year and the month, depending on what information is available, but you want to be able to encode this information in just one datatype. This is a problem which doesn't apply in very many other situations. (In answer to this question in the past, I've had techie types dismiss it as a problem with the data: your data is faulty!)
e.g., in a composer catalogue you are recording the fact that the composer dated a manuscript "January 1951". What can you put in a MySQL DATE field to represent this? "1951-01"? "1951-01-00"? Neither is really valid. Normally you end up encoding years, months and days in separate fields and then having to implement the semantics at application level. This is far from ideal.
If you're doing analytics against a fixed range of dates consider using a date dimension (fancy name for table) and use a foreign key into the date dimension. Check out this link:
http://www.ipcdesigns.com/dim_date/
If you use this date dimension consider how easily it will be to construct queries against any kind of dates you can think of.
SELECT * FROM my_table
JOIN DATE_DIM date on date.PK = my_table.date_FK
WHERE date.day = 30 AND
date.month = 1 AND
date.year = 2010
Or
SELECT * FROM my_table
JOIN DATE_DIM date on date.PK = my_table.date_FK
WHERE date.day_of_week = 1 AND
date.month = 1 AND
date.year = 2010
Or
SELECT *, date.day_of_week_name FROM my_table
JOIN DATE_DIM date on date.PK = my_table.date_FK
WHERE date.is_US_civil_holiday = 1