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• building SQL Query From another Query in php

  - by Nina

  Hello when I Try to built Query from another Query in php code I Faced some problem can you tell me why? :( code : $First="SELECT ro.RoomID,ro.RoomName,ro.RoomLogo,jr.RoomID,jr.MemberID,ro.RoomDescription FROM joinroom jr,rooms ro where (ro.RoomID=jr.RoomID)AND jr.MemberID = '1' "; $sql1 = mysql_query($First); $constract .= "ro.RoomName LIKE '%$search_each%'"; $constract="SELECT * FROM $sql1 WHERE $constract ";// This statment is Make error

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• Convert this Linq query from query syntax to lambda expression

  - by Jinkinz

  I'm not sure I like linq query syntax...its just not my preference. But I don't know what this query would look like using lambda expressions, can someone help? from securityRoles in user.SecurityRoles from permissions in securityRoles.Permissions where permissions.SecurableEntity.Name == "Unit" && permissions.PermissionType.Name == "Read" orderby permissions.PermissionLevel.Value descending select permissions There is a many-to-many relationship between users and security roles that makes this extra confusing. Thanks! Kelly

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• EF query to fluent nhibernate query

  - by Shlomi Levi

  I have EF Query: IEnumerable<Account> accounts = (from a in dc.Accounts join m in dc.GroupMembers on a.AccountID equals m.AccountID where m.GroupID == GroupID && m.IsApproved select a).Skip((_configuration.NumberOfRecordsInPage * (PageNumber - 1))) .Take(_configuration.NumberOfRecordsInPage); How to write it in fluent nhibernate query with Session.CreateCriteria<? (My problem is with Join) Regards,

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• cakephp datetime insertion behaviour

  - by littlechad

  hi everyone this is a cakePHP question about datetime database insertion mismatch, i jumped in to this project while the whole thing is already built around 70%. here's what happen, every time i insert a data that contain a datetime, the inserted time doesn't match the inputted date, and the mismatch has no pattern or what ever, in some table the differences is 5 hours, while in others it could be 12 hours, 7 hours, or even 15 hours. i have traced this by investigating the controller, the model, the app_controller, everything but i don't find anything that indicate a datetime insertion rules. if the view : echo $form->input('start_date', array('label' => __l('start date')); i can't even find in the controller anything like: $this->data['current_controller']['start_date'] = $this->data['current_controller']['start_date']; when i use pr($this-data); to print the posted data, this is shown: [start_date] => Array ( [month] => 02 [day] => 16 [year] => 2011 [hour] => [min] => [meridian] => ) so i figured doing something like: $yearMonDay = $this->data['current_controller']['start_date']['year']."-"; $yearMonDay .= $this->data['current_controller']['start_date']['month']."-"; $yearMonDay .= $this->data['current_controller']['start_date']['day']; if(!empty($this->data['current_controller']['start_date']['hour'])){ $hourMinSec = $this->data['current_controller']['start_date']['hour'].":"; $hourMinSec .= $this->data['current_controller']['start_date']['min'].":"; $hourMinSec .= $this->data['current_controller']['start_date']['meridian']; }else{ $hourMinSec = "00:00:00"; } $this->data['Deal']['start_date'] = $yearMonDay." ".$hourMinSec; just to make sure the funny thing is that those posted datetime is inserted into the database with the mismatch value anyway. it's getting pretty frustrating, is there any suggestion on where else should i find the codes that define how the datetime should be inserted? or probably give me a clue on how to override those mismatched insertion rules? thanks

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• Optimize GROUP BY&ORDER BY query

  - by Jan Hancic

  I have a web page where users upload&watch videos. Last week I asked what is the best way to track video views so that I could display the most viewed videos this week (videos from all dates). Now I need some help optimizing a query with which I get the videos from the database. The relevant tables are this: video (~239371 rows) VID(int), UID(int), title(varchar), status(enum), type(varchar), is_duplicate(enum), is_adult(enum), channel_id(tinyint) signup (~115440 rows) UID(int), username(varchar) videos_views (~359202 rows after 6 days of collecting data, so this table will grow rapidly) videos_id(int), views_date(date), num_of_views(int) The table video holds the videos, signup hodls users and videos_views holds data about video views (each video can have one row per day in that table). I have this query that does the trick, but takes ~10s to execute, and I imagine this will only get worse over time as the videos_views table grows in size. SELECT v.VID, v.title, v.vkey, v.duration, v.addtime, v.UID, v.viewnumber, v.com_num, v.rate, v.THB, s.username, SUM(vvt.num_of_views) AS tmp_num FROM video v LEFT JOIN videos_views vvt ON v.VID = vvt.videos_id LEFT JOIN signup s on v.UID = s.UID WHERE v.status = 'Converted' AND v.type = 'public' AND v.is_duplicate = '0' AND v.is_adult = '0' AND v.channel_id <> 10 AND vvt.views_date >= '2001-05-11' GROUP BY vvt.videos_id ORDER BY tmp_num DESC LIMIT 8 And here is a screenshot of the EXPLAIN result: So, how can I optimize this?

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• filling in the holes in the result of a query

  - by ????? ????????

  my query is returning: +------+------+------+------+------+------+------+-------+------+------+------+------+-----+ | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Bla | +------+------+------+------+------+------+------+-------+------+------+------+------+-----+ | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 | 0 | 13 | | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 | 0 | 0 | 14 | | 0 | 0 | 0 | 0 | 0 | 9 | 0 | 0 | 0 | 0 | 8 | 37 | 29 | | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 374 | 30 | | 0 | 0 | 1 | 0 | 78 | 2 | 4 | 8 | 57 | 169 | 116 | 602 | 31 | | 156 | 255 | 79 | 75 | 684 | 325 | 289 | 194 | 407 | 171 | 584 | 443 | 32 | | 1561 | 2852 | 2056 | 796 | 2004 | 1755 | 879 | 1052 | 1490 | 1683 | 2532 | 2381 | 33 | | 4167 | 3841 | 4798 | 3399 | 4132 | 5849 | 3157 | 4381 | 4424 | 4487 | 4178 | 5343 | 34 | | 5472 | 5939 | 5768 | 4150 | 7483 | 6836 | 6346 | 6288 | 6850 | 7155 | 5706 | 5231 | 35 | | 5749 | 4741 | 5264 | 4045 | 6544 | 7405 | 7524 | 6625 | 6344 | 5508 | 6513 | 3854 | 36 | | 5464 | 6323 | 7074 | 4861 | 7244 | 6768 | 6632 | 7389 | 8077 | 8745 | 6738 | 5039 | 37 | | 5731 | 7205 | 7476 | 5734 | 9103 | 9244 | 7339 | 8970 | 9726 | 9089 | 6328 | 5512 | 38 | | 7262 | 6149 | 8231 | 6654 | 9886 | 9834 | 9306 | 10065 | 9983 | 9984 | 6738 | 5806 | 39 | | 5886 | 6934 | 7137 | 6978 | 9034 | 9155 | 7389 | 9437 | 9711 | 8665 | 6593 | 5337 | 40 | +------+------+------+------+------+------+------+-------+------+------+------+------+-----+ as you can see the BLA column starts from 13. i want it to start from 1, then 2, then 3 etc......I do not want any gaps in the data. The reason there are gaps is because all of the months are 0 for that specific bla how do i get the result set to include ALL values for BLA, even ones that will yield 0 for the months? here are the desired results: +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+ | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Bla | +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+ | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 | | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 3 | | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 4 | | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 5 | | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 6 | | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 7 | | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 8 | | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 9 | | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 10 | | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 11 | | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 12 | | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 13 | | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 2 | 0 | 0 | 14 | | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 15 | | … | … | … | … | … | … | … | … | … | … | … | … | … | +-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+ here's my query: WITH CTE AS ( select sum(case when datepart(month,[datetime entered]) = 1 then 1 end) as Jan, sum(case when datepart(month,[datetime entered]) = 2 then 1 end) as Feb, sum(case when datepart(month,[datetime entered]) = 3 then 1 end) as Mar, sum(case when datepart(month,[datetime entered]) = 4 then 1 end) as Apr, sum(case when datepart(month,[datetime entered]) = 5 then 1 end) as May, sum(case when datepart(month,[datetime entered]) = 6 then 1 end) as Jun, sum(case when datepart(month,[datetime entered]) = 7 then 1 end) as Jul, sum(case when datepart(month,[datetime entered]) = 8 then 1 end) as Aug, sum(case when datepart(month,[datetime entered]) = 9 then 1 end) as Sep, sum(case when datepart(month,[datetime entered]) = 10 then 1 end) as Oct, sum(case when datepart(month,[datetime entered]) = 11 then 1 end) as Nov, sum(case when datepart(month,[datetime entered]) = 12 then 1 end) as Dec, DATEPART(yyyy,[datetime entered]) as [Year], bla= CASE WHEN datediff(d, CAST([datetime entered] as DATE), CAST([datetime completed] as DATE))*24 + CONVERT(CHAR(2),[datetime completed],108) >191 THEN 192 ELSE datediff(d, CAST([datetime entered] as DATE), CAST([datetime completed] as DATE))*24 + CONVERT(CHAR(2),[datetime completed],108) END --,datediff(d, CAST([datetime entered] as DATE), CAST([datetime completed] as DATE)) AS Sort_Days, --DATEPART(hour, [datetime completed] ) AS Sort_Hours from [TurnAround] group by datediff(d, CAST([datetime entered] as DATE), CAST([datetime completed] as DATE))*24 + CONVERT(CHAR(2),[datetime completed],108), DATEPART(yyyy,[datetime entered]) , [datetime entered] --[DateTime Completed] ) SELECT ISNULL(SUM(Jan),0) Jan, ISNULL(SUM(Feb),0) Feb, ISNULL(SUM(Mar),0) Mar, ISNULL(SUM(Apr),0) Apr, ISNULL(SUM(May),0) May, ISNULL(SUM(Jun),0) Jun, ISNULL(SUM(Jul),0) Jul, ISNULL(SUM(Aug),0) Aug, ISNULL(SUM(Sep),0) Sep, ISNULL(SUM(Oct),0) Oct, ISNULL(SUM(Nov),0) Nov, ISNULL(SUM(Dec),0) Dec, [year], --,Sort_Hours, --Sort_Days, A.RN Bla FROM ( SELECT *, RN=ROW_NUMBER() OVER(ORDER BY object_id) FROM sys.all_objects) A LEFT JOIN CTE B ON A.RN = CASE WHEN B.Bla > 191 THEN 192 ELSE B.Bla END WHERE A.RN BETWEEN 1 AND 192 GROUP BY A.RN,[year]

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• Adjusting Timezone - Convert XML DateTime to SQL DateTime

  - by noob.spt

  We are using TypedDataSet in our application. Data is passed to procedure in form of XML for insert/update. Now after populating DE with data, datetime remains the same though timezone information is added as below. Date in DB: 2009-10-29 18:52:53.43 Date in XML: 2009-10-29T18:52:53.43-05:00 Now when I am trying to convert below XML to SQL DateTime it is adjusting 5 hours and I am getting 2009-10-29 23:52:53.430 as the final output, which is wrong. Need to find a way to extract datetime from below XML snippet ignoring timezone. I have XML in following format, with timezone difference -05.00 <Order> <EnteredDateTime>2009-10-29T18:52:53.43-05:00</EnteredDateTime> </Order>

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• A typical mysql query( how to use subquery column into main query)

  - by I Like PHP

  I HAVE TWO TABLES shown below table_joining id join_id(PK) transfer_id(FK) unit_id transfer_date joining_date 1 j_1 t_1 u_1 2010-06-05 2010-03-05 2 j_2 t_2 u_3 2010-05-10 2010-03-10 3 j_3 t_3 u_6 2010-04-10 2010-01-01 4 j_5 NULL u_3 NULL 2010-06-05 5 j_6 NULL u_4 NULL 2010-05-05 table_transfer id transfer_id(PK) pastUnitId futureUnitId effective_transfer_date 1 t_1 u_3 u_1 2010-06-05 2 t_2 u_6 u_1 2010-05-10 3 t_3 u_5 u_3 2010-04-10 now i want to know total employee detalis( using join_id) which are currently working on unit u_3 . means i want only join_id j_1 (has transfered but effective_transfer_date is future date, right now in u_3) j_2 ( tansfered and right now in `u_3` bcoz effective_transfer_date has been passed) j_6 ( right now in `u_3` and never transfered) what i need to take care of below steps( as far as i know ) <1> first need to check from table_joining whether transfer_id is NULL or not <2> if transfer_id= is NULL then see unit_id=u_3 where joining_date <=CURDATE() ( means that person already joined u_3) <3> if transfer_id is NOT NULL then go to table_transfer using transfer_id (foreign key reference) <4> now see the effective_transfer_date regrading that transfer_id whether effective_transfer_date<=CURDATE() <5> if transfer date has been passed(means transfer has been done) then return futureUnitID otherwise return pastUnitID i used two separate query but don't know how to join those query?? for step <1 ans <2 SELECT unit_id FROM table_joining WHERE joining_date<=CURDATE() AND transfer_id IS NULL AND unit_id='u_3' for step<5 SELECT IF(effective_transfer_date <= CURDATE(),futureUnitId,pastUnitId) AS currentUnitID FROM table_transfer // here how do we select only those rows which have currentUnitID='u_3' ?? please guide me the process?? i m just confused with JOINS. i think using LEFT JOIN can return the data i need, or if we use subquery value to main query? but i m not getting how to implement ...please help me. Thanks for helping me alwayz

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• Help with SQL query (Calculate a ratio between two entitiess)

  - by Mestika

  Hi, I’m going to calculate a ratio between two entities but are having some trouble with the query. The principal is the same to, say a forum, where you say: A user gets points for every new thread. Then, calculate the ratio of points for the number of threads. Example: User A has 300 points. User A has started 6 thread. The point ratio is: 50:6 My schemas look as following: student(studentid, name, class, major) course(courseid, coursename, department) courseoffering(courseid, semester, year, instructor) faculty(name, office, salary) gradereport(studentid, courseid, semester, year, grade) The relations is a following: Faculity(name) = courseoffering(instructor) Student(studentid) = gradereport (studentid) Courseoffering(courseid) = course(courseid) Gradereport(courseid) = courseoffering(courseid) I have this query to select the faculty names there is teaching one or more students: SELECT COUNT(faculty.name) FROM faculty, courseoffering, gradereport, student WHERE faculty.name = courseoffering.instructor AND courseoffering.courseid = gradereport.courseid AND gradereport.studentid = student.studentid My problem is to find the ratio between the faculty members salary in regarding to the number of students they are teaching. Say, a teacher get 10.000 in salary and teaches 5 students, then his ratio should be 1:5. I hope that someone has an answer to my problem and understand what I'm having trouble with. Thanks Mestika

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• MS SQL datetime precision problem

  - by Nailuj

  I have a situation where two persons might work on the same order (stored in an MS SQL database) from two different computers. To prevent data loss in the case where one would save his copy of the order first, and then a little later the second would save his copy and overwrite the first, I've added a check against the lastSaved field (datetime) before saving. The code looks roughly like this: private bool orderIsChangedByOtherUser(Order localOrderCopy) { // Look up fresh version of the order from the DB Order databaseOrder = orderService.GetByOrderId(localOrderCopy.Id); if (databaseOrder != null && databaseOrder.LastSaved > localOrderCopy.LastSaved) { return true; } else { return false; } } This works for most of the time, but I have found one small bug. If orderIsChangedByOtherUser returns false, the local copy will have its lastSaved updated to the current time and then be persisted to the database. The value of lastSaved in the local copy and the DB should now be the same. However, if orderIsChangedByOtherUser is run again, it sometimes returns true even though no other user has made changes to the DB. When debugging in Visual Studio, databaseOrder.LastSaved and localOrderCopy.LastSaved appear to have the same value, but when looking closer they some times differ by a few milliseconds. I found this article with a short notice on the millisecond precision for datetime in SQL: Another problem is that SQL Server stores DATETIME with a precision of 3.33 milliseconds (0. 00333 seconds). The solution I could think of for this problem, is to compare the two datetimes and consider them equal if they differ by less than say 10 milliseconds. My question to you is then: are there any better/safer ways to compare two datetime values in MS SQL to see if they are exactly the same?

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• Wrong date with ruby Date.today and DateTime.now

  - by Rob

  I've installed ruby-1.8.6-p383 with RVM. System ruby is 1.9.1_p378-1 I'm getting the wrong date from Date.today and DateTime.now when using ruby 1.8.. Whereas Time.now is correct: irb(main):002:0> DateTime.now.to_s => "2126--1-10618T11:23:43+00:00" irb(main):004:0> Date.today.to_s => "2126--1-10618" irb(main):005:0> Time.now => Thu Jan 28 11:55:27 +0000 2010 All is well if I switch to ruby 1.9: irb(main):003:0> DateTime.now.to_s => "2010-01-28T11:58:51+00:00" irb(main):004:0> Date.today.to_s => "2010-01-28" irb(main):005:0> Time.now => 2010-01-28 11:59:05 +0000 Any advice on how to get DateTime to work properly in ruby 1.8 would be most appreciated!

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• Robust DateTime parser library for .NET

  - by Frank Krueger

  Hello, I am writing an RSS and Mail reader app in C# (technically MonoTouch). I have run into the issue of parsing DateTimes. I see a lot of variance in how dates are presented in the wild and have begun writing a function like this: public static DateTime ParseTime(string timeStr) { var formats = new string[] { "ddd, d MMM yyyy H:mm:ss \"GMT+00:00\"", "d MMM yyyy H:mm:ss \"EST\"", "yyyy-MM-dd\"T\"HH:mm:ss\"Z\"", "ddd MMM d HH:mm:ss \"+0000\" yyyy", }; try { return DateTime.Parse(timeStr); } catch (Exception) { } foreach (var f in formats) { try { var t = DateTime.ParseExact(timeStr, f, CultureInfo.InvariantCulture); return t; } catch (Exception) { } } return DateTime.MinValue; } This, well, makes me sick. Three points. (1) It's silly of me to think that I can actually collect a format list that will cover everything out there. (2) It's wrong! Notice that I'm treating an EST date time as UTC (since .NET seems oblivious to time zones). (3) I don't like using exceptions for logic. I am looking for an existing library (source only please) that is known to handle a bunch of these formats. Also, I would like to keep using UTC DateTimes throughout my code so whatever library is suggested should be able to produce DateTimes. Is there anything out there like this?

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• perl DateTime now() problem

  - by Sergey Sinkovskiy

  Having this script use DateTime; use DateTime::Format::Strptime; my $p = DateTime::Format::Strptime->new(pattern => '%F %T', time_zone => 'local'); my $dt1 = DateTime->now(time_zone=>'local')->set_time_zone('UTC'); my $dt2 = $p->parse_datetime('2010-10-23 14:10:02')->set_time_zone('UTC'); print Dumper($dt1->hms); print Dumper($dt2->hms); print Dumper($dt1 > $dt2); The problem is that $dt1 is off by 1 hour. Like $VAR1 = '12:09:55'; $VAR1 = '11:10:02'; $VAR1 = 1; If I remove set_time_zone('UTC') in both cases - dumped values are okay. My feel is that somewhere DST is taken into account unnecessarily, but can't find out. Update: I dumped $dt-time_zone-name and $dt-offset for both and that's what i get. $VAR1 = 'Europe/Kiev'; $VAR1 = 7200; $VAR1 = 'Europe/Kiev'; $VAR1 = 10800; How this could be possible?

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• Query design in SQL - ORDER BY SUM() of field in rows which meet a certain condition

  - by Christian Mann

  OK, so I have two tables I'm working with - project and service, simplified thus: project ------- id PK name str service ------- project_id FK for project time_start int (timestamp) time_stop int (timestamp) One-to-Many relationship. Now, I want to return (preferably with one query) a list of an arbitrary number of projects, sorted by the total amount of time spent at them, which is found by SUM(time_stop) - SUM(time_start) WHERE project_id = something. So far, I have SELECT project.name FROM service LEFT JOIN project ON project.id = service.project_id LIMIT 100 but I cannot figure out how what to ORDER BY.

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• Help with MySQL query

  - by Michael S.

  I have a table that contains the next columns: ip(varchar 255), index(bigint 20), time(timestamp) each time something is inserted there, the time column gets current timestamp. I want to run a query that returns all the rows that have been added in the last 24 hours. This is what I try to execute: SELECT ip, index FROM users WHERE ip = 'some ip' AND TIMESTAMPDIFF(HOURS,time,NOW()) < 24 And it doesn't work. Can someone help me out? Thanks :)

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• Cardinality Estimation Bug with Lookups in SQL Server 2008 onward

  - by Paul White

  Cost-based optimization stands or falls on the quality of cardinality estimates (expected row counts).  If the optimizer has incorrect information to start with, it is quite unlikely to produce good quality execution plans except by chance.  There are many ways we can provide good starting information to the optimizer, and even more ways for cardinality estimation to go wrong.  Good database people know this, and work hard to write optimizer-friendly queries with a schema and metadata (e.g. statistics) that reduce the chances of poor cardinality estimation producing a sub-optimal plan.  Today, I am going to look at a case where poor cardinality estimation is Microsoft’s fault, and not yours. SQL Server 2005 SELECT th.ProductID, th.TransactionID, th.TransactionDate FROM Production.TransactionHistory AS th WHERE th.ProductID = 1 AND th.TransactionDate BETWEEN '20030901' AND '20031231'; The query plan on SQL Server 2005 is as follows (if you are using a more recent version of AdventureWorks, you will need to change the year on the date range from 2003 to 2007): There is an Index Seek on ProductID = 1, followed by a Key Lookup to find the Transaction Date for each row, and finally a Filter to restrict the results to only those rows where Transaction Date falls in the range specified.  The cardinality estimate of 45 rows at the Index Seek is exactly correct.  The table is not very large, there are up-to-date statistics associated with the index, so this is as expected. The estimate for the Key Lookup is also exactly right.  Each lookup into the Clustered Index to find the Transaction Date is guaranteed to return exactly one row.  The plan shows that the Key Lookup is expected to be executed 45 times.  The estimate for the Inner Join output is also correct – 45 rows from the seek joining to one row each time, gives 45 rows as output. The Filter estimate is also very good: the optimizer estimates 16.9951 rows will match the specified range of transaction dates.  Eleven rows are produced by this query, but that small difference is quite normal and certainly nothing to worry about here.  All good so far. SQL Server 2008 onward The same query executed against an identical copy of AdventureWorks on SQL Server 2008 produces a different execution plan: The optimizer has pushed the Filter conditions seen in the 2005 plan down to the Key Lookup.  This is a good optimization – it makes sense to filter rows out as early as possible.  Unfortunately, it has made a bit of a mess of the cardinality estimates. The post-Filter estimate of 16.9951 rows seen in the 2005 plan has moved with the predicate on Transaction Date.  Instead of estimating one row, the plan now suggests that 16.9951 rows will be produced by each clustered index lookup – clearly not right!  This misinformation also confuses SQL Sentry Plan Explorer: Plan Explorer shows 765 rows expected from the Key Lookup (it multiplies a rounded estimate of 17 rows by 45 expected executions to give 765 rows total). Workarounds One workaround is to provide a covering non-clustered index (avoiding the lookup avoids the problem of course): CREATE INDEX nc1 ON Production.TransactionHistory (ProductID) INCLUDE (TransactionDate); With the Transaction Date filter applied as a residual predicate in the same operator as the seek, the estimate is again as expected: We could also force the use of the ultimate covering index (the clustered one): SELECT th.ProductID, th.TransactionID, th.TransactionDate FROM Production.TransactionHistory AS th WITH (INDEX(1)) WHERE th.ProductID = 1 AND th.TransactionDate BETWEEN '20030901' AND '20031231'; Summary Providing a covering non-clustered index for all possible queries is not always practical, and scanning the clustered index will rarely be optimal.  Nevertheless, these are the best workarounds we have today. In the meantime, watch out for poor cardinality estimates when a predicate is applied as part of a lookup. The worst thing is that the estimate after the lookup join in the 2008+ plans is wrong.  It’s not hopelessly wrong in this particular case (45 versus 16.9951 is not the end of the world) but it easily can be much worse, and there’s not much you can do about it.  Any decisions made by the optimizer after such a lookup could be based on very wrong information – which can only be bad news. If you think this situation should be improved, please vote for this Connect item. © 2012 Paul White – All Rights Reserved twitter: @SQL_Kiwi email: [email protected]

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• Joda-Time: DateTime, DateMidnight and LocalDate usage

  - by fraido

  Joda-Time library includes different datetime classes DateTime - Immutable replacement for JDK Calendar DateMidnight - Immutable class representing a date where the time is forced to midnight LocalDateTime - Immutable class representing a local date and time (no time zone) I'm wondering how are you using these classes in your Layered Applications. I see advantages in having almost all the Interfaces using LocalDateTime (at the Service Layer at least) so that my Application doesn't have to manage Timezones and can safely assume Times always in UTC. My app could then use DateTime to manage Timezones at the very beginning of the Execution's Flow. I'm also wondering in which scenario can DateMidnight be useful.

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• UNIX Timestamp to MySQL DATETIME

  - by Henk Denneboom

  Hi all, I have a table with statistics and a field named time with Unix Timestamps. There are about 200 rows in the table, but I would like to change the Unix timestamps to MySQL DATETIME. Without losing the current rows. What would be the best way to update the Unix Timestamp to MySQL's DATETIME? The current table: CREATE TABLE `stats` ( `id` int(11) unsigned NOT NULL auto_increment, `time` int(11) NOT NULL, `domain` varchar(40) NOT NULL, `ip` varchar(20) NOT NULL, `user_agent` varchar(255) NOT NULL, `domain_id` int(11) NOT NULL, PRIMARY KEY (`id`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 So the time (INT) should be a DATETIME field. Thanks in advance!

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• DateTime: Require the user to enter a time component

  - by Heinzi

  Checking if a user input is a valid date or a valid "date + time" is easy: .NET provides DateTime.TryParse (and, in addition, VB.NET provides IsDate). Now, I want to check if the user entered a date including a time component. So, when using a German locale, 31.12.2010 00:00 should be OK, but 31.12.2010 shouldn't. I know I could use DateTime.TryParseExact like this: Dim formats() As String = {"d.M.yyyy H:mm:ss", "dd.M.yyyy H:mm:ss", _ "d.MM.yyyy H:mm:ss", "d.MM.yyyy H:mm:ss", _ "d.M.yyyy H:mm", ...} Dim result = DateTime.TryParseExact(userInput, formats, _ Globalization.CultureInfo.CurrentCulture, ..., result) but then I would hard-code the German format of specifying dates (day dot month dot year), which is considered bad practice and will make trouble should we ever want to localize our application. In addition, formats would be quite a large list of all possible combinations (one digit, two digits, ...). Is there a more elegant solution?

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• DateTime Property not firing PropertyChanged event when changed

  - by Brent

  I'm working on a WPF MVVM application and I've got a TextBox on my view that is bound to a DateTime property on the ViewModel. Seems simple enough, but when I clear the text in the TextBox, the property never changes. In fact, it never even fires until I begin typing "4/1..." and then it fires. What can I do to fix this? Obviously I could bind the TextBox to a string property and then update the real property in the setter, but that's a bit of a hack. There's got to be a better way... ViewModel private DateTime _startDate; public DateTime StartDate { get { return _startDate; } set { _startDate = value; OnPropertyChanged("StartDate"); } } View <TextBox Text="{Binding Path=StartDate, UpdateSourceTrigger=PropertyChanged, ValidatesOnDataErrors=true}"/>

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• How should I check that a given argument is a datetime.date object?

  - by rmh

  I'm currently using an assert statement with isinstance. Because datetime is a subclass of date, I also need to check that it isn't an instance of datetime. Surely there's a better way? from datetime import date, datetime def some_func(arg): assert isinstance(arg, date) and not isinstance(arg, datetime),\ 'arg must be a datetime.date object' # ...

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• correlated query /subquery VS join query

  - by trojanwarrior3000

  can we always convert a usual subquery/correlated subquery to join type query?

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• Converting datetime.ctime() values to Unicode

  - by Malcolm

  I would like to convert datetime.ctime() values to Unicode. Using Python 2.6.4 running under Windows I can set my locale to Spanish like below: import locale locale.setlocale(locale.LC_ALL, 'esp' ) Then I can pass %a, %A, %b, and %B to ctime() to get day and month names and abbreviations. import datetime dateValue = datetime.date( 2010, 5, 15 ) dayName = dateValue.strftime( '%A' ) dayName 's\xe1bado' How do I convert the 's\xe1bado' value to Unicode? Specifically what encoding do I use? I'm thinking I might do something like the following, but I'm not sure this is the right approach. codePage = locale.getdefaultlocale()[ 1 ] dayNameUnicode = unicode( dayName, codePage ) dayNameUnicode u's\xe1bado' Malcolm

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• setting codeigniter mysql datetime column to time() always sets it to 0

  - by Jake

  Hi guys. I'm using Codeigniter for a small project, and my model works correctly except for the dates. I have a column defined: created_at datetime not null and my model code includes in its array passed into db-insert: 'created_at' = time() This produces a datetime value of 0000-00-00 00:00:00. When I change it to: 'created_at' = "from_unixtime(" . time() . ")" it still produces the 0 datetime value. What am I doing wrong? How can I set this field to the given unix time? Also, I know mysql sets TIMESTAMP columns automatically for you - I'm not interested in that solution here. So far I can't find a complete example of this on the web.

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• QSqlQuery UPDATE/INSERT DateTime with server's time (eg CURRENT_TIMESTAMP)

  - by Skinniest Man

  I am using QSqlQuery to insert data into a MySQL database. Currently all I care about is getting this to work with MySQL, but ideally I'd like to keep this as platform-independent as possible. What I'm after, in the context of MySQL, is to end up with code that effectively executes something like the following query: UPDATE table SET time_field=CURRENT_TIMESTAMP() WHERE id='5' The following code is what I have attempted, but it fails: QSqlQuery query; query.prepare("INSERT INTO table SET time_field=? WHERE id=?"); query.addBindValue("CURRENT_TIMESTAMP()"); query.addBindValue(5); query.exec(); The error I get is: Incorrect datetime value: 'CURRENT_TIMESTAMP()' for column 'time_field' at row 1 QMYSQL3: Unable to execute statement. I am not surprised as I assume Qt is doing some type checking when it binds values. I have dug through the Qt documentation as well as I know how, but I can't find anything in the API designed specifically for supporting MySQL's CURRENT_TIMESTAMP() function, or that of any other DBMS. Any suggestions?

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