I recently discovered an old Microsoft Access database I made for recording a list of books and ticking off which ones I've read and in what year.
At the moment, this includes a BOOKS table which has a column for 'Read' and 'Year'. The query which generates the table of results gets the year column and counts how many books were read in each year, e.g:
2010: 8
2011: 10
2012: 20
However, this means that if no books are marked as read in, for example, 2015, then 2015 is just left out of the chart completely. Ideally it would show up with a value of 0.
Is there any way of doing this? I don't mind delving into the SQL itself. So far my initial thoughts are working out the number of years from 2010 to current year (using DateDiff), and somehow iterating over those years to count the number of books read... but I don't know if that's possible in SQL.
Create a numbers table with one row for each year in your target year range. Then LEFT JOIN that table to BOOKS and do your counting ...
SELECT n.the_number, Nz(Count(b.Year), 0) AS books_read
FROM
numbers AS n
LEFT JOIN BOOKS AS b
ON n.the_number = b.Year
WHERE n.the_number BETWEEN 2010 AND Year(Date())
GROUP BY n.the_number;
Note you would not need the WHERE clause if your numbers table contains only the years you're interested in. However a numbers table can be useful in other situations where you might want a different range of numbers. So a similar WHERE clause will allow you to target a specific subset of the numbers contained in the table.
Related
I have two years worth of data that I'm summing up for instance
Date | Ingredient_cost_Amount| Cost_Share_amount |
I'm looking at two years worth of data for 2012 and 2013,
I want to roll up all the totals so I have only two rows, one row for 2012 and one row for 2013. How do I write a SQL statement that will look at the dates but display only the 4 digit year vs 8 digit daily date. I suspect the sum piece of it will be taken care of by summing those columns withe calculations, so I'm really looking for help in how to tranpose a daily date to a 4 digit year.
Help is greatly appreciated.
select DATEPART(year,[Date]) [Year]
, sum(Ingredient_cost_Amount) Total
from #table
group by DATEPART(year,[Date])
Define a range/grouping table.
Something similar to the following should work in most RDBMSs:
SELECT Grouping.id, SUM(Ingredient.ingredient_cost_amount) AS Ingredient_Cost_Amount,
SUM(Ingredient.cost_share_amount) AS Cost_Share_Amount
FROM (VALUES (2013, DATE('2013-01-01'), DATE('2014-01-01')),
(2012, DATE('2012-01-01'), DATE('2013-01-01'))) Grouping(id, gStart, gEnd)
JOIN Ingredient
ON Ingredient.date >= Grouping.gStart
AND Ingredient.date < Grouping.gEnd
GROUP BY Grouping.id
(DATE() and related conversion functions are heavily DB dependent. Some RDBMSs don't support using VALUES this way, although there are other ways to create the virtual grouping table)
See this blog post for why I used an exclusive upper bound for the range.
Using a range table this way will potentially allow the db to use indices to help with the aggregation. How much this helps depends on a bunch of other factors, like the specific RDBMS used.
I have two database in SQL Server. I wanted to find out the data older than (let say 3) years.
I know the database creation date, currently I have around 550 GB (both the database) of data spanned for 7 years, I wanted to know 'how much of the DB data (out of total 550 GB)is older than 3 years OR (5 years)'?
I was going through this link but couldn't get the expected data.
SQL SERVER – Query to find number Rows, Columns, ByteSize for each table in the current database – Find Biggest Table in Database
One of the solution coming in my mind right now is to find out the total number of rows accounted for 7 years (easily get this number), total number of rows accounted for 5 years (starting from the date creation) (don't know how to get this number).
then for row_count_7_years accounts for 550 GB of data , what will be the row_count_5_years? i will get the approx data.
Please Help
For such purposes you should keep some datetime field as marc mentioned. I suppose you don't have it.
In you suggested solution you can get the whole count of rows from your table (for 7 years i suppose), but you wouldn't be able to get the rows for 5 years, because there is no date.
You can get the whole number of records for 7 years and divide them on the number of years, and ONLY IN CASE you have your database avarage fulfill, you can make query for top (numberOFRows in one year)*5 and order them by row_number(). The result - the rows, you should delete. But I wouldn't recommend you to use this solution.
I would recommend you to alter your tables and add the datetime columns for each of them. Before that you should make the backup for the whole date and copy it somewhere. After 3 years you would be able to make your clean up.
as mentioned above u shud have a date column , however if you dont , depending on the realtionships in your tables u might be able to estimate the number of rows looking up realtionships with some other table that has the datetime column , else if you have a backup ( unlikely but still) you can restore that to identify the delta
Wondering if anyone can help with the code for this.
I want to query the data and get 2 entries, one for YTD previous year and one for this year YTD.
Only way I know how to do this is as 2 separate queries with where clauses.. I would prefer to not have to run the query twice.
One column called DatePeriod and populated with 2011 YTD and 2012YTD, would be even better if I could get it to do 2011YTD, 2012YTD, 2011Total, 2012Total... though guessing this is 4 queries.
Thanks
EDIT:
In response to help clear a few things up:
This is being coded in MS SQL.
The data looks like so: (very basic example)
Date | Call_Volume
1/1/2012 | 4
What I would like is to have the Call_Volume summed up, I have queries that group it by week, and others that do it by month. I could pull all the dailies in and do this in Excel but the table has millions of rows so always best to reduce the size of my output.
I currently group by Week/Month and Year and union all so its 1 output. But that means I have 3 queries accessing the same table, large pain, very slow not efficient and that is fine but now I also need a YTD so its either 1 more query or if I could find a way to add it to the yearly query that would ideal:
So
DatePeriod | Sum_Calls
2011 Total | 40
2011 YTD | 12
2012 Total | 45
2012 YTD | 15
Hope this makes any sense.
SQL is built to do operations on rows, not columns (you select columns, of course, but aggregate operations are all on rows).
The most standard approach to this is something like:
SELECT SUM(your_table.sales), YEAR(your_table.sale_date)
FROM your_table
GROUP BY YEAR(your_table.sale_date)
Now you'll get one row for each year on record, with no limit to how many years you can process. If you're already grouping by another field, that's fine; you'll then get one row for each year in each of those groups.
Your program can then iterate over the rows and organize/render them however you like.
If you absolutely, positively must have columns instead, you'll be stuck with something like this:
SELECT SUM(IF(YEAR(date) = 2011, sales, 0)) AS total_2011,
SUM(IF(YEAR(date) = 2012, total_2012, 0)) AS total_2012
FROM your_table
If you're building the query programmatically you can add as many of those column criteria as you need, but I wouldn't count on this running very efficiently.
(These examples are written with some MySQL-specific functions. Corresponding functions exist for other engines but the syntax would be a little different.)
I am wondering if it's possible (without actually parsing the given string) to get the actual range (in terms of days, minutes or seconds) that is specified when you have an SQL statement like
[select 'x'
from dual
where date between to_date('20111113152049')
and to_date('20120113152049')]
I am working on a query where I'm given a string in the form of
"between to_date(A) and to_date(B)"
and would like to get that value in days to compare to a policy we let the user set so they don't enter a date range longer than say a week.
Assuming you're looking for a theoretical answer (that is: don't take this into production) this could work:
Prerequistes:
have three tables: days_seq(day_seq), month_seq(mth_seq) and year_seq(yr_seq)
days has the numbers 1...31, month 1..12, years 2011....?
Use te following query (I used access because I don't have proper RDBMS available here, keep in mind that MS-ACCESS/JET is forgiving in the use of the Dateserial function, that is, it doesn't break when you ask the dateserial for february, 30th, 2012)
SELECT Max(DateSerial(
[year_seq]![yr_seq]
,[month_seq]![mth_seq]
, [days_seq]![day_seq]))
-
Min(DateSerial(
[year_seq]![yr_seq]
,[month_seq]![mth_seq]
,[days_seq]![day_seq])) AS days
FROM days_seq, month_seq, year_seq
WHERE DateSerial(
[year_seq]![yr_seq]
,[month_seq]![mth_seq]
,[days_seq]![day_seq])
BETWEEN #2012-02-1# AND #2012-02-28#
The query basically produces a carthesian product of three tables which generates all possible days in months, months in a year for as many years as you have in the years table.
Bonus:
You could off-course generate a permanent Calendar table as X-Zero suggests.
table calendar([date])
INSERT INTO calendar
SELECT DISTINCT DateSerial(
[year_seq]![yr_seq]
,[month_seq]![mth_seq]
, [days_seq]![day_seq]))
FROM days_seq, month_seq, year_seq
You still have to pick your start year and your end year wisely. According to the Maya's an enddate of december 21st, 2012 will do.
I have 2 tables from which i need to run a query to display number of views a user had in the last 3 months from now.
So far I have come up with: all the field types are correct.
SELECT dbo_LU_USER.USERNAME
, Count(*) AS No_of_Sessions
FROM dbo_SDB_SESSION
INNER JOIN dbo_LU_USER
ON dbo_SDB_SESSION.FK_USERID = dbo_LU_USER.PK_USERID
WHERE (((DateDiff("m",[dbo_SDB_SESSION].[SESSIONSTART],Now()))=0
Or (DateDiff("m",[dbo_SDB_SESSION].[SESSIONSTART],Now()))=1
Or (DateDiff("m",[dbo_SDB_SESSION].[SESSIONSTART],Now()))=2))
GROUP BY dbo_LU_USER.USERNAME;
Basically, the code above display a list of all records within the past 3 months; however, it starts from the 1st day of the month and ends on the current date, but I need it to start 3 months prior to today's date.
Also to let you know this is SQL View in MS Access 2007 code.
Thanks in advance
Depending on how "strictly" you define your 3 months rule, you could make things a lot easier and probably efficient, by trying this:
SELECT dbo_LU_USER.USERNAME, Count(*) AS No_of_Sessions
FROM dbo_SDB_SESSION
INNER JOIN dbo_LU_USER
ON dbo_SDB_SESSION.FK_USERID = dbo_LU_USER.PK_USERID
WHERE [dbo_SDB_SESSION].[SESSIONSTART] between now() and DateAdd("d",-90,now())
GROUP BY dbo_LU_USER.USERNAME;
(Please understand that my MS SQL is a bit rusty, and can't test this at the moment: the idea is to make the query scan all record whose date is between "TODAY" and "TODAY-90 days").