I have large table and I need to do some one time processing on each record of table. Processing take 1 second for 1 row. Table has more than 500k record . I can't go with one query. I'm planning to run my query parallel by 5 part. Each run on 100k records. How to read distinct 100k record by each query so that 1 row process only once.
I would consider using ntile. Here is an example:
select column1, ntile(5) over (order by Column1)
from
(
select 1 as Column1
union all select 2
union all select 3
union all select 4
union all select 5
union all select 6
union all select 7
union all select 8
union all select 9
union all select 10
) as b
Sir I want to generate a series of integers say (from 1 to 1000) using query statement. BUT i do not want to use any Table nor want to create any Table.
I know this is possible in SQL Server but show the similar query for MS-Access 2003 too.
What you describe cannot be done in a single Access SQL query.
It you do not want to create a table. Then in Access I only think that you have this option left:
Select 1
Union All Select 2
Union All Select 3
Union All Select 4
Union All Select 5
Union All Select 6
Union All Select 7
Union All Select 8
Union All Select 9
Union All Select 10
Union All Select 11
--And so on
I'm querying a support ticket database, and each ticket has a column for "date opened" and "date closed." Tickets frequently remain open for multiple days, so we need to be able to pull the number of tickets that are OPEN on each day.
For example, for 4/8/14, we need to know how many tickets were opened on 4/8, combined with the total number of unclosed tickets that were opened prior to 4/8 but remained still open at 12:00am on 4/8 (may or may not have been closed during or after 4/8).
This seems straightforward enough for a single date, but now I need to write a query that will pull a complete range of dates.
For example, we need to write a query that returns every date between 1/1/14 and 4/10/14 along with the total number of tickets open on each date (including dates on which 0 tickets were open).
Is this possible using only queries or subqueries, without using any stored procedures or temporary datatables?
We're currently pulling the data into Excel and calculating the date stats there, but Excel is not a scalable solution and we'd like to have SQL perform this work so we can migrate this report to SSRS (SQL Server Reporting Services) down the road.
Your question is not very clear to me, but with SQLServer 2005 or better (SQLServer 2008 or better for the type Date) you can create a calendar. This one the way to do it
WITH [counter](N) AS
(SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1 UNION ALL SELECT 1 UNION ALL SELECT 1 UNION ALL
SELECT 1)
, days(N) AS (SELECT row_number() over (ORDER BY (SELECT NULL)) FROM [counter])
, months (N) AS (SELECT N - 1 FROM days WHERE N < 13)
SELECT DISTINCT CAST(DATEADD(DAY, days.n,
DATEADD(MONTH, months.n, '20131231')
) AS date)
FROM months
CROSS JOIN days
ORDER BY 1
if you need more year just add a new cte accordingly
SQLFiddle
You can't do it, without having some sort of date table that contains a row for each date possible. Creating a date table is pretty easy, depending on your RDBMS and your requirements.
How would I do this in SQL Server? (I know it won't run as written but it illustrates the question better than I can explain)
SELECT SQRT(number) WHERE number IN (4,9,16,25)
It would return multiple rows of course
you can use table value constructor
select sqrt(number)
from (
values (4),(9),(16),(25)
) as T(number)
or use union all
select sqrt(number)
from (
select 4 union all
select 9 union all
select 16 union all
select 25
) as T(number)
sql fiddle demo
You could create a derived table:
SELECT SQRT(number)
FROM (
SELECT 4 AS number
UNION ALL SELECT 9
UNION ALL SELECT 16
UNION ALL SELECT 25
) A
Sorry about the vague subject but I couldn't think what to put.
Here's my problem, I'm doing a query on a table that returns me a count of items related to a day. I want to make sure that if I do a query on the DB, I always get a set number of rows. For example, imagine I have the following table that contains a log of when people log into a website:
**WebsiteLogin**
id: Integer
login_date: Datetime
I can then get counts of the logins for each date by doing something like:
SELECT DATE(login_date), COUNT(*) FROM WebsiteLogin GROUP BY DATE(login_date)
Which works great and will return me the data I want. But imagine my website was quite unpopular on the weekends. The data returned would look like:
2008-12-10, 100
2008-12-11, 124
2008-12-12, 151
2008-12-15, 141
2008-12-16, 111
The 13th & 14th are missing because there was no data for those dates. Is there any way I can change my query so that I get data that includes all the dates I query on. E.g.
2008-12-10, 100
2008-12-11, 124
2008-12-12, 151
2008-12-13, 0
2008-12-14, 0
2008-12-15, 141
2008-12-16, 111
I imagine I could do this if I set up a table containing all the dates in a year and then using a left/right join but that's really messy way of doing it.
So any clues on a nice way to do this in SQL? Or is programmatically my only choice? Cheers for any input.
To do this you would need to write a stored procedure that returns a table result.
It would use a loop that would step thru each day and get the count and store it in a row of a temp table, then return that table as the resultset.
Here is a MS SQL server example of a loop:
http://www.databasejournal.com/features/mssql/article.php/3100621/T-SQL-Programming-Part-2---Building-a-T-SQL-Loop.htm
I imagine I could do this if I set up a table containing all the dates in a year and then using a left/right join but that's really messy way of doing it.
Nope. That's pretty much how to do it. On the other hand, you can use a temporary table and populate it with just the date range required.
If only MS SQL had virtual tables, where you provided a generator function...
You shouldn't need to create a temporary table, or similar, you just need a source with enough rows to construct the missing dates:
I don't know mysql, but if it supports "connect by" then you could do the following:
(this is in oracle)
select d login_date, count(login_date) count
from
websitelogin wsl
right outer join (
select start_date+l-1 d from (select start_date, level l
from (select min(login_date) start_date, max(login_date)-min(login_date)+1 num_days
from websitelogin) connect by level <= num_days)) v on d=login_date
group by d
/
if mysql doesn't have connect by you could just join on some arbitrary table with enough rows in it instead and limit the result to the number of required rows:
select d login_date, count(login_date) count
from
websitelogin wsl
right outer join (select start_date+rownum-1 d from
(
select
min(login_date) start_date,
max(login_date)-min(login_date)+1 num_days
from websitelogin)v,all_objects
where rownum<=num_days
) v on d=login_date
group by d
not quite as neat though, and obviously you need to know that the driving table has enough rows in it.
I know it isn't mysql, but I use the following function in MSSQL (see below for MySql version):
CREATE FUNCTION dbo.DatesBetween (#start_date datetime, #end_date datetime)
RETURNS #DateTable TABLE (gen_date datetime)
AS
BEGIN
DECLARE #num_dates int
DECLARE #tmpVal TABLE (a_count int identity(0,1))
SELECT #num_dates = datediff(day, #start_date, #end_date)
WHILE (select isnull(max(a_count), 0) from #tmpVal) < #num_dates
INSERT #tmpVal DEFAULT VALUES
INSERT #DateTable (gen_date)
SELECT dateadd(day, a_count, #start_date) FROM #tmpVal
RETURN
END
So, to use it in your example, I would try something like:
DECLARE #min_date datetime, #max_date datetime
SELECT #min_date = min(login_date), #max_date = max(login_date)
FROM WebsiteLogin
SELECT m.gen_date 'login_date', isnull(l.num_visits, 0) 'num_visits'
FROM dbo.DatesBetween(#min_date, #max_date) as d
LEFT OUTER JOIN (SELECT DATE(login_date) 'login_date', COUNT(*) 'num_visits'
FROM WebsiteLogin
GROUP BY DATE(login_date)) AS l ON d.gen_date = l.login_date
Alternatively, and with a massive speed improvement on my query, you could investigate this blog entry, which does what my code above does, but will work across all versions of SQL.
He explains it more there, but the SQL is:
DECLARE #LowDate DATETIME
SET #LowDate = '01-01-2006'
DECLARE #HighDate DATETIME
SET #HighDate = '12-31-2016'
SELECT DISTINCT DATEADD(dd, Days.Row, DATEADD(mm, Months.Row, DATEADD(yy, Years.Row, #LowDate))) AS Date
FROM
(SELECT 0 AS Row UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4
UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9
UNION ALL SELECT 10 UNION ALL SELECT 11 UNION ALL SELECT 12 UNION ALL SELECT 13 UNION ALL SELECT 14
UNION ALL SELECT 15 UNION ALL SELECT 16 UNION ALL SELECT 17 UNION ALL SELECT 18 UNION ALL SELECT 19
UNION ALL SELECT 20 UNION ALL SELECT 21 UNION ALL SELECT 22 UNION ALL SELECT 23 UNION ALL SELECT 24
UNION ALL SELECT 25 UNION ALL SELECT 26 UNION ALL SELECT 27 UNION ALL SELECT 28 UNION ALL SELECT 29
UNION ALL SELECT 30 -- add more years here...
) AS Years
INNER JOIN
(SELECT 0 AS Row UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4
UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9
UNION ALL SELECT 10 UNION ALL SELECT 11
) AS Months
ON DATEADD(mm, Months.Row, DATEADD(yy, Years.Row, #LowDate)) <= #HighDate
INNER JOIN
(SELECT 0 AS Row UNION ALL SELECT 1 UNION ALL SELECT 2 UNION ALL SELECT 3 UNION ALL SELECT 4
UNION ALL SELECT 5 UNION ALL SELECT 6 UNION ALL SELECT 7 UNION ALL SELECT 8 UNION ALL SELECT 9
UNION ALL SELECT 10 UNION ALL SELECT 11 UNION ALL SELECT 12 UNION ALL SELECT 13 UNION ALL SELECT 14
UNION ALL SELECT 15 UNION ALL SELECT 16 UNION ALL SELECT 17 UNION ALL SELECT 18 UNION ALL SELECT 19
UNION ALL SELECT 20 UNION ALL SELECT 21 UNION ALL SELECT 22 UNION ALL SELECT 23 UNION ALL SELECT 24
UNION ALL SELECT 25 UNION ALL SELECT 26 UNION ALL SELECT 27 UNION ALL SELECT 28 UNION ALL SELECT 29
UNION ALL SELECT 30
) AS Days
ON DATEADD(dd, Days.Row, DATEADD(mm, Months.Row, DATEADD(yy, Years.Row, #LowDate))) <= #HighDate
WHERE DATEADD(yy, Years.Row, #LowDate) <= #HighDate
ORDER BY 1