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• Premature optimization is the root of all evil, but can it ever be too late?

  - by polygenelubricants

  "We should forget about small efficiencies, say about 97% of the time: premature optimization is the root of all evil" So what is that 3% like? Can the avoidance of premature optimization ever be taken too extreme that it does more harm than good? Even if it's rare, has there been a case of a real measurable software engineering disaster due to complete negligence to optimize early in the process? Bonus question: is software engineering pretty much the only field that has such a counter intuitive principle regarding doing something earlier rather than later before things potentially become too big a problem to fix? Personal question: how do you justify something as premature optimization and not just a case of you being lazy/ignorant/dumb?

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• mysql query - syntax error - cannot find out why

  - by Phil Jackson

  Hi all, im taring my hair out over this one. A query is throwing an error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'FROM, SUBJECT, DATE, READ, MAIL ) VALUES ( 'EJackson', 'dfdf', '1270974101', 'fa' at line 1 I printed out the query to see what could be the problem: INSERT INTO db.tablename ( FROM, SUBJECT, DATE, READ, MAIL ) VALUES ( 'EJackson', 'dfdf', '1270974299', 'false', 'dfdsfdsfd' ) and finaly the structure consists of: CREATE TABLE db.tablename ( `ID` int(12) NOT NULL auto_increment, `FROM` varchar(255) NOT NULL, `SUBJECT` varchar(255) NOT NULL, `DATE` varchar(255) NOT NULL, `READ` varchar(255) NOT NULL, `MAIL` varchar(255) NOT NULL, PRIMARY KEY (`ID`) ) ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ; I cant find anything wrong. Any Help would be much appreciated. ( db.tablename is a replacement for the actual tablename )

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• Django query filter a set of data

  - by dana

  if a have a query like following = Relations.objects.filter(initiated_by = request.user) in which i'm having all the users followed by the currently logged in user, and i want to display those user's blog posts. Using a query like: blog = New.objects.filter(created_by = following) it only shows me the blog posts of the user with the id = 1 (though the currently logged in user doesn't actually follow him) in template i have : {% for object in blog %} <a href='/accounts/profile_view/{{object.created_by}}/'> {{object.created_by}}</a> <br /> {{object.post}}<br /> {% endfor %} Where am i wrong?

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• How to make query on a property from a joined table in Hibernate using Criteria

  - by Palo

  Hello, I have the following mapping: <hibernate-mapping package="server.modules.stats.data"> <class name="User" table="user"> <id name="id"> <generator class="native"></generator> </id> <many-to-one name="address" column="addressId" unique="true" lazy="false" /> </class> <class name="Address" table="address"> <id name="id"> <generator class="native"></generator> </id> <property name="street" /> </class> </hibernate-mapping> How can I do a Criteria query to select all users living on some street? That is create Criteria query for this SQL: Select * from user join address on user.addressId = address.id where address.street='someStreet'

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• Multiple Class in JDO Query

  - by Dan Delgado

  Hello, I'm currently developing in GAE and I have to query like this using JDO: SELECT table1.column1, table2.column2 FROM table1, table2 WHERE table1.column1 = table2.column1; I tried this one but it won't work: String query = "select from "+Assessment.class.getName()+ "a, "+ Project.class.getName()+" p where a.projectId == p.id && p.owner=='"+owner+"'"; Is this valid or this really isn't supported yet? If this is valid, why is it not working then? If it isn't, what should I do to make this work? Thank you!

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• Linq query challenge - can this be done?

  - by vdh_ant

  My table structure is as follows: Person 1-M PesonAddress Person 1-M PesonPhone Person 1-M PesonEmail Person 1-M Contract Contract M-M Program Contract M-1 Organization At the end of this query I need a populated object graph where each person has their: PesonAddress's PesonPhone's PesonEmail's PesonPhone's Contract's - and this has its respective Program's Now I had the following query and I thought that it was working great, but it has a couple of problems: from people in ctx.People.Include("PersonAddress") .Include("PersonLandline") .Include("PersonMobile") .Include("PersonEmail") .Include("Contract") .Include("Contract.Program") where people.Contract.Any( contract => (param.OrganizationId == contract.OrganizationId) && contract.Program.Any( contractProgram => (param.ProgramId == contractProgram.ProgramId))) select people; The problem is that it filters the person to the criteria but not the Contracts or the Contract's Programs. It brings back all Contracts that each person has not just the ones that have an OrganizationId of x and the same goes for each of those Contract's Programs respectively. What I want is only the people that have at least one contract with an OrgId of x with and where that contract has a Program with the Id of y... and for the object graph that is returned to have only the contracts that match and programs within that contract that match. I kinda understand why its not working, but I don't know how to change it so it is working... This is my attempt thus far: from people in ctx.People.Include("PersonAddress") .Include("PersonLandline") .Include("PersonMobile") .Include("PersonEmail") .Include("Contract") .Include("Contract.Program") let currentContracts = from contract in people.Contract where (param.OrganizationId == contract.OrganizationId) select contract let currentContractPrograms = from contractProgram in currentContracts let temp = from x in contractProgram.Program where (param.ProgramId == contractProgram.ProgramId) select x where temp.Any() select temp where currentContracts.Any() && currentContractPrograms.Any() select new Person { PersonId = people.PersonId, FirstName = people.FirstName, ..., ...., MiddleName = people.MiddleName, Surname = people.Surname, ..., ...., Gender = people.Gender, DateOfBirth = people.DateOfBirth, ..., ...., Contract = currentContracts, ... }; //This doesn't work But this has several problems (where the Person type is an EF object): I am left to do the mapping by myself, which in this case there is quite a lot to map When ever I try to map a list to a property (i.e. Scholarship = currentScholarships) it says I can't because IEnumerable is trying to be cast to EntityCollection Include doesn't work Hence how do I get this to work. Keeping in mind that I am trying to do this as a compiled query so I think that means anonymous types are out.

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• Add column from another table matching results from first MySQL query

  - by Nemi

  This is my query for available rooms in choosen period: SELECT rooms.room_id FROM rooms WHERE rooms.room_id NOT IN ( SELECT reservations.room_id FROM reservations WHERE ( reservations.arrivaldate >= $arrival_datetime AND reservations.departuredate <= $departure_datetime) OR ( reservations.arrivaldate <= $arrival_datetime AND reservations.departuredate >= $arrival_datetime ) OR ( reservations.arrivaldate <= $departure_datetime AND reservations.departuredate >= $departure_datetime ) ); How to add average room price column for selected period(from $arrival_datetime to $departure_datetime) from another table (room_prices_table), for every room_id returned from above query. So I need to look in columns whos name is same as room_id... room_prices_table: date room0001 room0002 room0003 ... Something like SELECT AVG(room0003) FROM room_prices_table WHERE datum IS BETWEEN $arrival_datetime AND $departure_datetime ??

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• MySQL Query exceptions

  - by Wayne

  In one page, it should show records that has the following selected month from the drop down menu and it is set in the ?month=March So the query will do this $sql = "SELECT * FROM schedule WHERE month = '" . Clean($_GET['month']) . "' AND finished='0' ORDER BY date ASC"; But it shows records that has a value of 2 in the finished column and I don't want the query to include this. I've tried $sql = "SELECT * FROM schedule WHERE month = '" . Clean($_GET['month']) . "' AND finished='0' OR finished = '1' OR finished = '3' ORDER BY date ASC"; But it shows records on different months when it shouldn't be. So basically I want the record to exclude the records that has the value of 2 in the record that will not be shown in the page.

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• MySQL date query only returns one year, when multiple exist

  - by Bowman

  I'm a part-time designer/developer with a part-time photography business. I've got a database of photos with various bits of metadata attached. I want to query the database and return a list of the years that photos were taken, and the quantity of photos that were taken in that year. In short, I want a list that looks like this: 2010 (35 photos) 2009 (67 photos) 2008 (48 photos) Here's the query I'm using: SELECT YEAR(date) AS year, COUNT(filename) as quantity FROM photos WHERE visible='1' GROUP BY 'year' ORDER BY 'year' DESC Instead of churning out all the possible years (the database includes photos from 2010-2008), this is the sole result: 2010 (35 photos) I've tried a lot of different syntax but at this point I'm giving in and asking for help!

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• MySQL query to find customers who have made the most orders

  - by zzapper

  tbl_customer.id is the customer's id tbl_order.customer_id a query that will select all customers with say 4 or more records in tbl_order

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• Django finding which field matched in a multiple OR query

  - by Greg Hinch

  I've got a couple models which are set up something like this: class Bar(models.Model): baz = models.CharField() class Foo(models.Model): bar1 = models.ForeignKey(Bar) bar2 = models.ForeignKey(Bar) bar3 = models.ForeignKey(Bar) And elsewhere in the code, I end up with an instance of Bar, and need to find the Foo it is attached to in some capacity. Right now I came up with doing a multiple OR query using Q, something like this: foo_inst = Foo.objects.get(Q(bar1=bar_inst) | Q(bar2=bar_inst) | Q(bar3=bar_inst)) What I need to figure out is, which of the 3 cases actually hit, at least the name of the member (bar1, bar2, or bar3). Is there a good way to do this? Is there a better way to structure the query to glean that information?

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• Different Paramater Value Results In Slow Query

  - by alphadogg

  I have an sproc in SQL Server 2008. It basically builds a string, and then runs the query using EXEC(): SELECT * FROM [dbo].[StaffRequestExtInfo] WITH(nolock,readuncommitted) WHERE [NoteDt] < @EndDt AND [NoteTypeCode] = @RequestTypeO AND ([FNoteDt] >= @StartDt AND [FNoteDt] <= @EndDt) AND [FStaffID] = @StaffID AND [FNoteTypeCode]<>@RequestTypeC ORDER BY [LocName] ASC,[NoteID] ASC,[CNoteDt] ASC All but @RequestTypeO and @RequestTypeF are passed in as sproc parameters. The other two are built from a parameter into local variables. Normally, the query runs under one second. However, for one particular value of @StaffID, the execution plan is different and about 30x slower. In either case, the amount of data returned is generally the same, but execution time goes way up. I tried to recompile the sproc. I also tried to "copy" @StaffID into a local @LocalStaffID. Neither approach made any difference. Any ideas?

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• Having problem in sql query execution

  - by Rishi2686

  Hi there, I have a problem in sql query execution.I am using this sql query: $userid = 1; $sql = mysql_query(" SELECT ID, Nm, Address, date_format(DateOfBirth, '%d%M%Y') as DateOfBirth FROM PersonalDetails where UserMasterID = $userid ") or die (mysql_error()); The result appears as: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '= ' at line 1 When I execute this in PHPMyAdmin it works properly. I am using mysql(5.0.5b) and PHP (5.2.6) Can you help me please?

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• How to structure this query...?

  - by SpikETidE

  Hi Everyone... Consider the following table.... hotel facilities 1 internet 1 swimming pool 1 wi-fi 1 parking 2 swimming pool 2 sauna 2 parking 3 toilets 3 bungee-jumping 3 internet 4 parking 4 swimming pool I need to select only the hotels that have parking, swimming pool and internet....? I worked out the following.... SELECT hotel FROM table WHERE facilties IN(internet, swimming pool, parking) This query selects the hotels that has atleast one among the choices. But what i need is a query that selects the hotels that has ALL of the selected facilities... Thanks for your suggestions....

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• MySQL query : all records of one table plus count of another table

  - by Ricardo

  Hello Guys! I have 2 tables: User and Picture. The Picture table has the key of the user. So basically each user can have multiple pictures, and each picture belongs to one user. Now, I am trying to make the following query: I want to select all the user info plus the total number of pictures that he has (even if it's 0). How can I do that? Probably it sounds quite simple, but I am trying and trying and can't seem to find the right query. The only thing I could select is this info, but only for users that have at least 1 picture, meaning that the Pictures table has at least one record for that key... But I also wanna consider the users that don't have any. Any idea? Thanks!

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• Mysql slow query: INNER JOIN + ORDER BY causes filesort

  - by Alexander

  Hello! I'm trying to optimize this query: SELECT `posts`.* FROM `posts` INNER JOIN `posts_tags` ON `posts`.id = `posts_tags`.post_id WHERE (((`posts_tags`.tag_id = 1))) ORDER BY posts.created_at DESC; The size of tables is 38k rows, and 31k and mysql uses "filesort" so it gets pretty slow. I tried to use different indexes, no luck. CREATE TABLE `posts` ( `id` int(11) NOT NULL auto_increment, `created_at` datetime default NULL, PRIMARY KEY (`id`), KEY `index_posts_on_created_at` (`created_at`), KEY `for_tags` (`trashed`,`published`,`clan_private`,`created_at`) ) ENGINE=InnoDB AUTO_INCREMENT=44390 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci CREATE TABLE `posts_tags` ( `id` int(11) NOT NULL auto_increment, `post_id` int(11) default NULL, `tag_id` int(11) default NULL, `created_at` datetime default NULL, `updated_at` datetime default NULL, PRIMARY KEY (`id`), KEY `index_posts_tags_on_post_id_and_tag_id` (`post_id`,`tag_id`) ) ENGINE=InnoDB AUTO_INCREMENT=63175 DEFAULT CHARSET=utf8 +----+-------------+------------+--------+--------------------------+--------------------------+---------+---------------------+-------+-----------------------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+------------+--------+--------------------------+--------------------------+---------+---------------------+-------+-----------------------------------------------------------+ | 1 | SIMPLE | posts_tags | index | index_post_id_and_tag_id | index_post_id_and_tag_id | 10 | NULL | 24159 | Using where; Using index; Using temporary; Using filesort | | 1 | SIMPLE | posts | eq_ref | PRIMARY | PRIMARY | 4 | .posts_tags.post_id | 1 | | +----+-------------+------------+--------+--------------------------+--------------------------+---------+---------------------+-------+-----------------------------------------------------------+ 2 rows in set (0.00 sec) What kind of index I need to define to avoid mysql using filesort? Is it possible when order field is not in where clause?

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• StreamInsight complex query with filter on HoppingWindow

  - by hh354

  I'm trying out StreamInsight and I came across a problem with a query I need. I'm trying to throw a warning if there are several changes in my measured values (of up to 20% change) in the last 30 minutes. This is the query I came up with for now but it isn't working and it's not even correct I think. Apparently I can't filter on a window...? var deviationQuery = from s in wcfStream group s by s.SensorId into grouped from window in grouped.HoppingWindow(TimeSpan.FromMinutes(30),TimeSpan.FromMinutes(1)) where window.StdDev(e => e.Value) > measurableValue * 1.2 select new OutputEvent { Error = "Deviation" }; Thanks in advance!

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• How To Query Many-to-Many Table (one table's values becomes column headers)

  - by CRice

  Given this table structure, I want to flatten out the many-to-many relationships and make the values in the Name field of one table into column headers and the quantities from the same table into column values. The current idea which will work is to put the values into a Dictionary (hashtable) and represent this data in code but im wondering if there is a SQL way to do this. I am also using Linq-to-SQL for data access so a Linq-to-SQL solution would be ideal. [TableA] (int Id) [TableB] (int id, string Name) [TableAB] (int tableAId, int tableBId, int Quantity) fk: TableA.Id joins to TableAB.tableAId fk: TableB.Id joins to TableAB.tableBId Is there a way I can query the three tables and return one result for example: TableA [Id] 1 TableB [Id], [Name] 1, "Red" 2, "Green" 3, "Blue" TableAB [TableAId], [TableBId], [Quantity] 1 1 5 1 2 6 1 3 7 Query Result: [TableA.Id], [Red], [Green], [Blue] 1, 5, 6, 7

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• MySQL Query WHERE Including CASE or IF?

  - by handfix

  Strange problem. My Query looks like SELECT DISTINCT ID, `etcetc`, `if/elses over muliple joined tables` FROM table1 AS `t1` # some joins, eventually unrelated in that context WHERE # some standard where statements, they work/ CASE WHEN `t1`.`field` = "foo" THEN (`t1`.`anOtherField` != 123 AND `t1`.`anOtherField` != 456 AND `t1`.`anOtherOtherField` != "some String") WHEN `t1`.`field` = "bar" THEN `t1`.`aSecondOtherField` != 12345 END #ORDER BY CASE etc. Standard Stuff Apperantly MySQL returns a wrong rowcount and I think my problem is in the logic of the WHERE ... CASE statement. Maybe with the brackets? Maybe I should go for operator OR and not AND? Should my the second WHEN include brackets also, even when I only compare one field? Should I use IF and not CASE? Basically I want to exclude some rows with specific values IF theres a specific value in field foo or bar I would try that all out, but it takes a huge amount of time to complete that query... :(

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• SQL query showing element more than once.

  - by Sorin Cioban

  Hi guys, I have the following SQL query but it doesn't entirely work because it shows each element more than once. select c.name, c.director, c.title, count(c.title) as numfilms from casting c join casting c1 on c1.name = c.name Group by c.name, c.director, c.title Having count (c.title) > 1 order by numfilms So what it does it shows which actors have made more than 1 film. But unfortunately, this query shows each actor as many times as the number of movies he made. Using distinct doesn't work as actor may have been in different movie with same title and different director.

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• Display PHP Query Array in the table

  - by Jerry

  Hi all I would like to display my Query from Mysql on the table. However, my data is like this: Array([0]=>data1, [1]=>data2, [2]=>data3,[3]=>data4,[4]=>pic1,[5]=>pic2,[6]=>pic3,[7]=>pic4); I want to display my table as |data1 | data2 |data3 |data4 |pic1 | pic2 |pic3 |pic4 I know how to display the data in the single ling like td or tr but not sure how to do tr and td on the same loop. Any helps? Thanks in advance! while($query=mysql_fetch_array($dataQuery)){ //not sure what to do here. }

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• Why Solr admin query page interprets UTF-8 as ISO-8859-1

  - by Scott Chu

  I deploy a war to my Tomcat 6.0.35 on Win7 64bit and when I use full-interface query page (I mean form.jsp) in Solr Admin to query 2 Chinese character (say it's C1C2) , the debug info shows: <lst name="debug"> <str name="rawquerystring">æ°è</str> <str name="querystring">æ°è</str> <str name="parsedquery">NEWSID:æ°è</str> <str name="parsedquery_toString">NEWSID:æ°è</str> ... You can see C1C2 becomes æ°è. I deploy same war file to Tomcat on Linux or on another Win7 64bit of my colleagues' computer, the encoding acts well. Does anyone know why and how can I avoid this problem? Thanks in advance!

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• How to get a dynamic attribute name in cfloop over query in ColdFusion

  - by Kip

  I'm inside a cfloop over a query. I want to get an attribute, but I won't know what that attribute will be until runtime. Using #qryResult[MyAttr]# fails with the error "Complex object types cannot be converted to simple values." What is the syntax for doing this? Here is a simplified example: <cfquery datasource="TestSource" name="qryResult"> SELECT * FROM MyTable </cfquery> <cfloop query="qryResult"> <cfset MyAttr="autoid" /> <cfoutput> Test 1: #qryResult.autoid# <br/> <!--- succeeds ---> Test 2: #qryResult[MyAttr]# <br/> <!--- fails ---> </cfoutput> </cfloop>

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• MS SQL Query Question

  - by Lp1

  Running MS SQL 2008, and I am definitely a new SQL user. I have a table that has 4 columns: EmpNum, User, Action, Updatetime A user logs into, and out of a system, it is registered in the database. For example, if user1 logs into the system, then out 5 minutes later, a simple query (select * from update) would look like: EmpNum User Action Updatetime 1 User1 I 2010-01-01 23:00:00:000 1 User1 O 2010-01-01 23:05:00:000 I'm trying to query the Empnum, User, Action, I(in time), O(out time), and the total time. Any help or a point in the right direction, and I would be eternally grateful. :)

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• Query to find all bars that sell three different beers at the same price

  - by Eternal Learner

  Query to find "All bars that sell three different beers at the same price?" My Tables are Sells(bar,beer,price) - bar - foreign Key.. Bars(name,addr) - name primary key. I thought of something like this but that dosent seem to work ... Select A.bar As bar , B.bar as bar From Sells AS A, Sells AS B Where A.bar = B.bar and A.beer <> B.beer Group By(A.beer) Having Count(Distinct A.beer) >= 2 Is this the correct SQL query ?

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