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  • Are GUID primary keys bad in theory, or just practice?

    - by Yarin
    Whenever I design a database I automatically start with an auto-generating GUID primary key for each of my tables (excepting look-up tables) I know I'll never lose sleep over duplicate keys, merging tables, etc. To me it just makes sense philosophically that any given record should be unique across all domains, and that that uniqueness should be represented in a consistent way from table to table. I realize it will never be the most performant option, but putting performance aside, I'd like to know if there are philosophical arguments against this practice?

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  • MySQL: Count occurrences of known (or enumerated) distinct values

    - by Eilidh
    After looking at how to count the occurrences of distinct values in a field, I am wondering how to count the occurrences of each distinct value if the distinct values are known (or enumerated). For example, if I have a simple table - TrafficLight Colour ------------ ------ 1 Red 2 Amber 3 Red 4 Red 5 Green 6 Green where one column (in this case Colour) has known (or enumerated) distinct values, how could I return the count for each colour as a separate value, rather than as an array, as in the linked example. To return an array with a count of each colour (using the same method as in the linked example), the query would be something like SELECT Colour COUNT(*) AS ColourCount FROM TrafficLights GROUP BY Colour, and return an array - Colour ColourCount ------ ----------- Red 3 Amber 1 Green 2 What I would like to do is to return the count for each Colour AS a separate total (e.g. RedCount). How can I do this?

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  • Conditionally set a column to its default value in Postgres

    - by Evgeny
    I've got a PostgreSQL 8.4 table with an auto-incrementing, but nullable, integer column. I want to update some column values and, if this column is NULL then set it to its default value (which would be an integer auto-generated from a sequence), but I want to return its value in either case. So I want something like this: UPDATE mytable SET incident_id = COALESCE(incident_id, DEFAULT), other = 'somethingelse' WHERE ... RETURNING incident_id Unfortunately, this doesn't work - it seems that DEFAULT is special and cannot be part of an expression. What's the best way to do this?

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  • MySQL query to order by parent then child places

    - by Swanny
    I have a table of pages in my database, each page can have a parent as below: id parent_id title 1 0 Home 2 0 Sitemap 3 0 Products 4 3 Product 1 5 3 Product 2 6 4 Product 1 Review Page What would be the best MySQL query to select all pages ordered by parent then child then child again if there is more than one level, there will be a maximum of three levels. The above example would produce the desired order: Home Sitemap Products Product 1 Product 1 Review Page Product 2

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  • How can I use multiple Datatables on my CrystalReport?

    - by Sergio Tapia
    I have a dataset that connects with three databases. How can I attach my Crystalreport viewer so all three are included? protected void Page_Load(object sender, EventArgs e) { ReportDocument X = new ReportDocument(); DataTable DTable = new DataTable(); DataSet1TableAdapters.TableAdapterManager ????? = new WebApplication1.DataSet1TableAdapters.TableAdapterManager(); DTable = ???????? string ubicacion = Server.MapPath("crystalReport1.rpt"); X.Load(ubicacion); X.SetDataSource(DTable); CrystalReportViewer1.ReportSource = X; }

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  • SSAS dimension source table changed - how to propagate changes to analysis server?

    - by Phil
    Hi, Sorry if the question isn't phrased very well but I'm new to SSAS and don't know the correct terms. I have changed the name of a table and its columns. I am using said table as a dimension for my cube, so now the cube won't process. Presumably I need to make updates in the analysis server to reflect changes to the source database? I have no idea where to start - any help gratefully received. Thanks Phil

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  • Fact table with multiple facts

    - by Jeff Meatball Yang
    I have a dimension (SiteItem) has two important facts: perUserClicks perBrowserClicks however, within this dimension, I have groups of dimensions based on an attribute column (let's call the groups AboveFoldItems, LeftNavItems, OnTheFlyItems, etc.) each have more facts that are specific to that group: AboveFoldItems: eyeTime, loadTime LeftNavItems: mouseOverTime OnTheFlyItems: doesn't have any extra, but may in the future Is the following fact table schema ok? DateKey SessionKey SiteItemKey perUserClicks perBrowserClicks eyeTime loadTime mouseOverTime It seems a little wasteful since only some columns pertain to some dimension keys (the irrelevant facts are left NULL). But... this seems like it would be a common problem, so there should be a common solution for this, right?

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  • Put logic behind generated LinqToSql fields

    - by boris callens
    In a database I use throughout several projects, there is a field that should actually be a boolean but is for reasons nobody can explain to me a field duplicated over two tables where one time it is a char ('Y'/'N') and one time an int (1/0). When I generate a datacontext with LinqToSql the fields off course gets these datatypes. It would be nice if I don't have to drag this stupid choice of datatype throughout the rest of my application. Is there a way to give the generated classes a little bit of logic that just return me return this.equals('Y'); and return this==1; Preferably without having to make an EXTRA field in my partial class. It would be a solution to give the generated field a totally different name that can only be accessed through the partial class and then generate the extra field with the original name with my custom logic in the partial class. I don't know how to alter the accesibility level in my generated class though.. Any suggestions?

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  • Help with a MySQL SELECT WHERE Clause

    - by Dr. DOT
    A column in my table contains email addresses. I have a text string that contains the a few usernames of email addresses separated by commas. I can make text sting into an array if necessary to get my SELECT WHERE clause to work correctly. Text string search argument is 'bob,sally,steve' I want to produce a WHERE clause that only returns rows where the username portion of the email address in the table matches one of the usernames in my text string search argument. Thus a row with [email protected] would not be returned but [email protected] would be. Does anyone have a WHERE clause sample that produces this result? Thanks.

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  • How to map combinations of things to a relational database?

    - by Space_C0wb0y
    I have a table whose records represent certain objects. For the sake of simplicity I am going to assume that the table only has one row, and that is the unique ObjectId. Now I need a way to store combinations of objects from that table. The combinations have to be unique, but can be of arbitrary length. For example, if I have the ObjectIds 1,2,3,4 I want to store the following combinations: {1,2}, {1,3,4}, {2,4}, {1,2,3,4} The ordering is not necessary. My current implementation is to have a table Combinations that maps ObjectIds to CombinationIds. So every combination receives a unique Id: ObjectId | CombinationId ------------------------ 1 | 1 2 | 1 1 | 2 3 | 2 4 | 2 This is the mapping for the first two combinations of the example above. The problem is, that the query for finding the CombinationId of a specific Combination seems to be very complex. The two main usage scenarios for this table will be to iterate over all combinations, and the retrieve a specific combination. The table will be created once and never be updated. I am using SQLite through JDBC. Is there any simpler way or a best practice to implement such a mapping?

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  • How can I perform this query between related tables without using UNION?

    - by jeremy
    Suppose I have two separate tables that I watch to query. Both of these tables has a relation with a third table. How can I query both tables with a single, non UNION based query? I want the result of the search to rank the results by comparing a field on each table. Here's a theoretical example. I have a User table. That User can have both CDs and books. I want to find all of that user's books and CDs with a single query matching a string ("awesome" in this example). A UNION based query might look like this: SELECT "book" AS model, name, ranking FROM book WHERE name LIKE 'Awesome%' UNION SELECT "cd" AS model, name, ranking FROM cd WHERE name LIKE 'Awesome%' ORDER BY ranking DESC How can I perform a query like this without the UNION? If I do a simple left join from User to Books and CDs, we end up with a total number of results equal to the number of matching cds timse the number of matching books. Is there a GROUP BY or some other way of writing the query to fix this?

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  • MySQL Database Design with Internationalization

    - by Some name
    Hello, I'm going to start work on a medium sized application, and i'm planning it's db design. One thing that I'm not sure about is this. I will have many tables which will need internationalization, such as: "membership_options, gender_options, language_options etc" Each of these tables will share common i18n fields, like: "title, alternative_title, short_description, description" In your opinion which is the best way to do it? Have an i18n table with the same fields for each of the tables that will need them? or do something like: Membership table Gender table ---------------- -------------- id | created_at id | created_at 1 - 22.03.2001 1 - 14.08.2002 2 - 22.03.2001 2 - 14.08.2002 General translation table ------------------------- record_id | table_name | string_name | alternative_title| .... |id_language 1 - membership regular null 1 (english) 1 - membership normale null 2 (italian) 1 - gender man null 1(english) 1 -gender uomo null 2(italian) This would avoid me repeating something like: membership_translation table ----------------------------- membership_id | name | alternative_title | id_lang 1 regular null 1 1 normale null 2 gender_translation table ----------------------------- gender_id | name | alternative_title | id_lang 1 man null 1 1 uomo null 2 and so on, so i would probably reduce the number of db tables, but i'm not sure about performance.I'm not much of a DB designer, so please let me know.

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  • How to return a record from function executed by INSERT/UPDATE rule?

    - by seas
    Do the following scheme for my database: create sequence data_sequence; create table data_table { id integer primary key; field varchar(100); }; create view data_view as select id, field from data_table; create function data_insert(_new data_view) returns data_view as $$declare _id integer; _result data_view%rowtype; begin _id := nextval('data_sequence'); insert into data_table(id, field) values(_id, _new.field); select * into _result from data_view where id = _id; return _result; end; $$ language plpgsql; create rule insert as on insert to data_view do instead select data_insert(new); Then type in psql: insert into data_view(field) values('abc'); Would like to see something like: id | field ----+--------- 1 | abc Instead see: data_insert ------------- (1, "abc") Is it possible to fix this somehow? Thanks for any ideas. Ultimate idea is to use this in other functions, so that I could obtain id of just inserted record without selecting for it from scratch. Something like: insert into data_view(field) values('abc') returning id into my_variable would be nice but doesn't work with error: ERROR: cannot perform INSERT RETURNING on relation "data_view" HINT: You need an unconditional ON INSERT DO INSTEAD rule with a RETURNING clause. I don't really understand that HINT. I use PostgreSQL 8.4.

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  • TextBox value not updated

    - by Jignesh
    I am fetching data from database to textbox using Linq.When i try update the same textbox value,it does not work. DAL.TournamentsDataContext tdc = new SchoolSports.DAL.TournamentsDataContext(); var tournamentTable = tdc.GetTable<DAL.Tournament>(); var tournamentRecord = (from rec in tournamentTable where rec.TournamentId == TournamentId select rec).Single(); tournamentRecord.Tournament_type = Tournament_type; tournamentRecord.Tournament_Name = Tournament_Name; ; tournamentRecord.Tournament_Level = Tournament_Level; tournamentRecord.Tournament_For = Tournament_For; tournamentRecord.Country_Code = Country_Code; tournamentRecord.Tournament_Status = Tournament_Status; tournamentRecord.Tournament_begin_date = Tournament_begin_date; tournamentRecord.Tournament_end_date = Tournament_end_date; tournamentRecord.Sponsored_By = Sponsored_By; tournamentRecord.Tournament_Details = Tournament_Details; var organiserTable = tdc.GetTable<DAL.Organiser>(); var organiserRecord = (from rec in organiserTable where rec.Tournament_Id == TournamentId select rec).Single(); organiserRecord.Name_Of_Organiser = OrName; organiserRecord.Telephone = OrTeleNo; organiserRecord.Email = OrEmail; organiserRecord.Mobile = OrMobile; organiserRecord.Fax = OrFax; if (Tournament_For == "School") { var invitedSchoolIdTable = tdc.GetTable<DAL.Invited_School>(); var invitedSchoolIdRecord = (from rec in invitedSchoolIdTable where rec.Tournament_Id == TournamentId select rec).Single(); invitedSchoolIdRecord.School_Ids = SchoolUniIds; } if (Tournament_For == "University") { var invitedUniversityTable = tdc.GetTable<DAL.Invited_University>(); var invitedUniversityIdRecord = (from rec in invitedUniversityTable where rec.Tournament_Id == TournamentId select rec).Single(); invitedUniversityIdRecord.University_Ids = SchoolUniIds; } tdc.SubmitChanges();

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  • Assign values from same table

    - by Reddy S R
    I have a database table with parent child relationships between different rows. 1 parent can have any number of children. Children do not have children. I want to copy 'Message' from 'Parent Category' to child categories. CategoryID Name Value Message ParentID DeptId 1 Books 9 Specials 1 2 Music 7 1 3 Paperback 25 1 1 4 PDFs 26 1 2 5 CDs 35 2 1 If that was sample data, Paperback should have Specials as it's Message after the query is run. I have gotten the child rows (the query runs very slow, don't know why), but how do I get the data and assign it to appropriate child rows? --@DeptId = 1 select * from Categories where ParentID in( select CategoryID from Categories where DeptID = @DeptId ) I would like to see a solution that would not use cursors. Thanks

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  • Checking for reciprocal relationships in mysql. A trivial one table problem.

    - by calumbrodie
    I have a mysql table that stores relationships. Items can be related to another item in one direction, or both items can be related to each other. I want to return all items related to my primary item - but I also want to check to see if the related item has a 'reverse relationship' to the current item and show this as a boolean |--------------|---------------| | SKU | related_SKU | |--------------|---------------| | 0001 | 0099 | | 0002 | 0099 | | 0099 | 0001 | |--------------|---------------| If I want to get all relationships for SKU=0001 SELECT related_SKU from relationships where SKU='0001' returns |--------------| | related_SKU | |--------------| | 0099 | |--------------| but what I want is |--------------|---------------| | related_SKU | reciprocal | |--------------|---------------| | 0099 | 1 | |--------------|---------------| or SELECT related_SKU from relationships where SKU='0002' |--------------|---------------| | related_SKU | reciprocal | |--------------|---------------| | 0099 | 0 | |--------------|---------------| What's the best way to do this?

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  • Multiple LIKE in SQL

    - by ninumedia
    I wanted to search through multiple rows and obtain the row that contains a particular item. The table in mySQL is setup so each id has a unique list (comma-delimited) of values per row. Ex: id | order 1 | 1,3,8,19,34,2,38 2 | 4,7,2,190,38 Now if I wanted to pull the row that contained just the number 19 how would I go about doing this? The possibilities I could figure in the list with a LIKE condition would be: 19, ,19 ,19, I tried the following and I cannot obtain any results, Thank you for your help! SELECT * FROM categories WHERE order LIKE '19,%' OR '%,19%' OR '%,19%' LIMIT 0 , 30

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  • Where to store site settings: DB? XML? CONFIG? CLASS FILES?

    - by Emin
    I am re-building a news portal of which already have a large number of visits every day. One of the major concerns when re-building this site was to maximize performance and speed. Having said this, we have done many things from caching, to all sort of other measures to ensure speed. Now towards the end of the project, I am having a dilemma of where to store my site settings that would least affect performance. The site settings will include things such as: Domain, DefaultImgPath, Google Analytics code, default emails of editors as well as more dynamic design/display feature settings such as the background color of specific DIVs and default color for links etc.. As far as I know, I have 4 choices in storing all these info. Database: Storing general settings in the DB and caching them may be a solution however, I want to limit the access to the database for only necessary and essential functions of the project which generally are insert/update/delete news items, author articles etc.. XML: I can store these settings in an XML file but I have not done this sort of thing before so I don't know what kind of problems -if any- I might face in the future. CONFIG: I can also store these settings in web.config CLASS FILE: I can hard code all these settings in a SiteSettings class, but since the site admin himself will be able to edit these settings, It may not be the best solution. Currently, I am more close to choosing web.config but letting people fiddle with it too often is something I do not want. E.g. if somehow, I miss out a validation for something and it breaks the web.config, the whole site will go down. My concern basically is that, I cannot forsee any possible consequences of using any of the methods above (or is there any other?), I was hoping to get this question over to more experienced people out here who hopefully help make my decision.

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  • What's the most efficient query?

    - by Aaron Carlino
    I have a table named Projects that has the following relationships: has many Contributions has many Payments In my result set, I need the following aggregate values: Number of unique contributors (DonorID on the Contribution table) Total contributed (SUM of Amount on Contribution table) Total paid (SUM of PaymentAmount on Payment table) Because there are so many aggregate functions and multiple joins, it gets messy do use standard aggregate functions the the GROUP BY clause. I also need the ability to sort and filter these fields. So I've come up with two options: Using subqueries: SELECT Project.ID AS PROJECT_ID, (SELECT SUM(PaymentAmount) FROM Payment WHERE ProjectID = PROJECT_ID) AS TotalPaidBack, (SELECT COUNT(DISTINCT DonorID) FROM Contribution WHERE RecipientID = PROJECT_ID) AS ContributorCount, (SELECT SUM(Amount) FROM Contribution WHERE RecipientID = PROJECT_ID) AS TotalReceived FROM Project; Using a temporary table: DROP TABLE IF EXISTS Project_Temp; CREATE TEMPORARY TABLE Project_Temp (project_id INT NOT NULL, total_payments INT, total_donors INT, total_received INT, PRIMARY KEY(project_id)) ENGINE=MEMORY; INSERT INTO Project_Temp (project_id,total_payments) SELECT `Project`.ID, IFNULL(SUM(PaymentAmount),0) FROM `Project` LEFT JOIN `Payment` ON ProjectID = `Project`.ID GROUP BY 1; INSERT INTO Project_Temp (project_id,total_donors,total_received) SELECT `Project`.ID, IFNULL(COUNT(DISTINCT DonorID),0), IFNULL(SUM(Amount),0) FROM `Project` LEFT JOIN `Contribution` ON RecipientID = `Project`.ID GROUP BY 1 ON DUPLICATE KEY UPDATE total_donors = VALUES(total_donors), total_received = VALUES(total_received); SELECT * FROM Project_Temp; Tests for both are pretty comparable, in the 0.7 - 0.8 seconds range with 1,000 rows. But I'm really concerned about scalability, and I don't want to have to re-engineer everything as my tables grow. What's the best approach?

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  • Detecting changes between rows with same ID

    - by Noah
    I have a table containing some names and their associated ID, along with a snapshot: snapshot, id, name I need to identify when a name has changed for an id between snapshots. For example, in the following data: 1, 0, 'MOUSE_SPEED' 1, 1, 'MOUSE_POS' 1, 2, 'KEYBOARD_STATE' 2, 0, 'MOUSE_BUTTONS' 2, 1, 'MOUSE_POS' 2, 2, 'KEYBOARD_STATE' ...the meaning of id 0 changed with snapshot 2, but the others remained the same. I'd like to construct a query that (ideally) returns: 1, 0, 'MOUSE_SPEED' 2, 0, 'MOUSE_BUTTONS' I am using PostgreSQL v8.4.2.

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  • Detecting abuse for post rating system

    - by Steven smethurst
    I am using a wordpress plugin called "GD Star Rating" to allow my users to vote on stories that I post to one of my websites. http://everydayfiction.com/ Recently we have been having a lot of abuse of the system. Stories that have obviously been voted up artificially. "GD Star Rating" creates some detailed logs when a user votes on a story. Including; IP, Time of vote, and user_adgent, ect.. For example this story has 181 votes with an average of 5.7 http://www.everydayfiction.com/snowman-by-shaun-simon/ Most other stories only get around ~40 votes each day. At first I thought that the story got on to a social bookmarking site Digg, Stumbleupon ect... but after checking the logs I found that this story is getting the same amount of traffic that a normal story gets ~2k-3k. I checked if all the votes for this perpendicular story where coming from a the same IP address. I could see this happening if a user was at a school's computer lab using all their lab computers to vote up this story. Not one duplicate IP address in the log for this story. SELECT ip, COUNT(*) as count FROM wp_gdsr_votes_log WHERE id=3932 GROUP BY (ip ) ORDER BY count DESC Next I thought that a use might be using a proxy to vote up a story. I checked this by grouping all the browser user_agent together to see if there a single browser voting in a perpendicular way. At most 7 users where using a similar browser but voted sporadically (1-5), no evidence of wrong doing. SELECT user_agent, COUNT(*) as count FROM wp_gdsr_votes_log WHERE id=3932 GROUP BY ( user_agent) ORDER BY count DESC I check was to see if all the votes came in at a once. Maybe someone has a really interesting bot that can change the user_adgent and uses proxies, ect... At most 5 votes came with in 2 mins of each other. It doesn't seem to be any regularity on how people vote (IE a 5 vote does not come in once a min) SELECT * FROM wp_gdsr_votes_log WHERE id =3932 AND vote=5 ORDER BY wp_gdsr_votes_log.voted DESC The obvious solution to this problem is to force people to login before they are allowed to vote. But I would prefer to not have to go down that route unless it is absolutely necessary. I'm looking for suggestions on things to test for to detect the abuse.

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