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  • Voting Script, Possibility of Simplifying Database Queries

    - by Sev
    I have a voting script which stores the post_id and the user_id in a table, to determine whether a particular user has already voted on a post and disallow them in the future. To do that, I am doing the following 3 queries. SELECT user_id, post_id from votes_table where postid=? AND user_id=? If that returns no rows, then: UPDATE post_table set votecount = votecount-1 where post_id = ? Then SELECT votecount from post where post_id=? To display the new votecount on the web page Any better way to do this? 3 queries are seriously slowing down the user's voting experience Edit In the votes table, vote_id is a primary key In the post table, post_id is a primary key. Any other suggestions to speed things up?

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  • mysql: get all rows into 1 column

    - by andufo
    hi, i have 3 tables: post (id_post, title) tag (id_tag, name) post_tag (id_post_tag, id_post, id_tag) Lets suppose that id_post 3 has 4 linked tags 1,2,3,4 (soccer, basket, tennis and golf). Is there a way to return something like this in ONE row? col 1 id_post = 3 col 2 tags = soccer basket tennis golf Thanks

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  • Using NULL in MySQL

    - by JPro
    The data in my dabatase comes from an external source and where ever there is no data passed, I keep NULL in those places. Can anyone tell me if there are any implications in using NULL to represent empty value? Should I follow some other convention like 'data_not_available'? or something like that? Can anyone suggest?

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  • MySQL, return only rows where there are duplicates among two columns.

    - by Richard Waite
    I have a table in MySQL of contact information ; first name, last name, address, etc. I would like to run a query on this table that will return only rows with first and last name combinations which appear in the table more than once. I do not want to group the "duplicates" (which may only be duplicates of the first and last name, but not other information like address or birthdate) - I want to return all the "duplicate" rows so I can look over the results and determine if they are dupes or not. This seemed like it would be a simple thing to do, but it has not been. Every solution I can find either groups the dupes and gives me a count only (which is not useful for what I need to do with the results) or doesn't work at all. Is this kind of logic even possible in a query ? Should I try and do this in Python or something?

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  • How would I implement separate databases for reading and writing operations?

    - by Matt
    I am interested in implementing an architecture that has two databases one for read operations and the other for writes. I have never implemented something like this and have always built single database, highly normalised systems so I am not quite sure where to begin. I have a few parts to this question. 1. What would be a good resource to find out more about this achitecture? 2. Is it just a question of replicating between two identical schemas, or would your schemas differ depending on the operations, would normalisation vary too? 3. How do you insure that data written to one database is immediately available for reading from the second? Any further help, tips, resources would be appreciated. Thanks.

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  • Will MySql caching cause performance problems?

    - by Camran
    I am about to upload my website onto a VPS. It is a classifieds website, where all data is stored in MySql and Solr. I wonder if when using MySql:s cache, the server will slow down? Ie, if somebody makes a search for the first time, and MySql is to cache the query, will the caching make the server slower than if it would not cache anything? After the caching is done I know things will improve in terms of performance... But I would like to know if I should even use the cache or not, what do you think? Thanks

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  • Why can't you return a List from a Compiled Query?

    - by Andrew
    I was speeding up my app by using compiled queries for queries which were getting hit over and over. I tried to implement it like this: Function Select(ByVal fk_id As Integer) As List(SomeEntity) Using db As New DataContext() db.ObjectTrackingEnabled = False Return CompiledSelect(db, fk_id) End Using End Function Shared CompiledSelect As Func(Of DataContext, Integer, List(Of SomeEntity)) = _ CompiledQuery.Compile(Function(db As DataContext, fk_id As Integer) _ (From u In db.SomeEntities _ Where u.SomeLinkedEntity.ID = fk_id _ Select u).ToList()) This did not work and I got this error message: Type : System.ArgumentNullException, mscorlib, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 Message : Value cannot be null. Parameter name: value However, when I changed my compiled query to return IQueryable instead of List like so: Function Select(ByVal fk_id As Integer) As List(SomeEntity) Using db As New DataContext() db.ObjectTrackingEnabled = False Return CompiledSelect(db, fk_id).ToList() End Using End Function Shared CompiledSelect As Func(Of DataContext, Integer, IQueryable(Of SomeEntity)) = _ CompiledQuery.Compile(Function(db As DataContext, fk_id As Integer) _ From u In db.SomeEntities _ Where u.SomeLinkedEntity.ID = fk_id _ Select u) It worked fine. Can anyone shed any light as to why this is? BTW, compiled queries rock! They sped up my app by a factor of 2.

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  • How to create a better tables Structure.

    - by user160820
    For my website i have tables Category :: id | name Product :: id | name | categoryid Now each category may have different sizes, for that I have also created a table Size :: id | name | categoryid | price Now the problem is that each category has also different ingredients that customer can choose to add to his purchased product. And these ingredients have different prices for different sizes. For that I also have a table like Ingredient :: id | name | sizeid | categoryid | price I am not sure if this Structure really normalized is. Can someone please help me to optimize this structure and which indexed do i need for this Structure?

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  • Migrating from mssql to firebird: pro and cons

    - by user193655
    i am considering the migration for 3 reasons: 1) SQLSERVER installation is a nightmar, expecially for 1-user software. Software installs in 10 seconds, SQLServer in 1 hour. Firebird installation is much easier. 2) SQLSERVER runs on windows server only 3) My customers have all the express edition 4) i am not using any advanced feature, I am now starting using filestream, but the main reason for this is that Express eidtion has 4/10GB db size limit So these are all Pros of moving to Firebird. Which are the cons? I can also plan to support both platiforms, but this will backfire I fear.

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  • (NOT) NULL for NVARCHAR columns

    - by Anders Abel
    Allowing NULL values on a column is normally done to allow the absense of a value to be represented. When using NVARCHAR there is aldready a possibility to have an empty string, without setting the column to NULL. In most cases I cannot see a semantical difference between an NVARCHAR with an empty string and a NULL value for such a column. Setting the column as NOT NULL saves me from having to deal with the possibility of NULL values in the code and it feels better to not have to different representations of "no value" (NULL or an empty string). Will I run into any other problems by setting my NVARCHAR columns to NOT NULL. Performance? Storage size? Anything I've overlooked on the usage of the values in the client code?

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  • How to: Display multiple related classes in an ASP.NET GridView ?

    - by kversch
    I would like to display students and their grades with a GridView and LinqToSQL like this: assignment1 assignment2 Student 1 55 89 Student 2 87 56 Student 3 92 34 I found this topic but it doesn't answer my question: http://forums.asp.net/t/1557987.aspx I have a many-to-many relationship between students and assignments called "grades". The grade for the assignment is stored in that table in a "gradeNumber" column. I would also like to specify which assignments should be displayed in the grid. Btw, my LINQ entities are extended to allow me to write/get studentx.Assignments or assignmentx.Students.

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  • Relation to multiple tables of different types for rating?

    - by Tronic
    i have a table structure like this Products Team Images and want to implement a rating/commenting-feature, where users can rate each entry of all tables. what's the best way to make a single rating table? e.g. a user votes a a product and a team entry, and it should be possible to get alle these entries from a single table. what kind of table-structure is best for this purpose? i hope, my questions is clear enough :/ thanks in advance!

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  • ORACLE: Parameter reference in WHERE doesn't work

    - by Gainder
    Hello, I have created a simple static function in oracle 10g to get the reference of an object based on his pk. STATIC FUNCTION getRef(nome IN VARCHAR2) RETURN REF folder_typ IS fl_r REF folder_typ := null; BEGIN SELECT REF(fl) INTO fl_r FROM folder_tab fl WHERE fl.nome = nome; RETURN fl_r; END getRef; This gives me an error because it could't fetch a row. If insted of WHERE fl.nome = nome; I write WHERE fl.nome = 'folder1'; -- it works. I think im not using the parameter in the right way. How can I use it?

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  • Beginner Ques::How to delete records permanently in case of linked tables?

    - by Serenity
    Let's say I have these 2 tables QuesType and Ques:- QuesType QuestypeID|QuesType |Active ------------------------------------ 101 |QuesType1 |True 102 |QuesType2 |True 103 |XXInActiveXX |False Ques QuesID|Ques|Answer|QUesTypeID|Active ------------------------------------ 1 |Ques1|Ans1 |101 |True 2 |Ques2|Ans2 |102 |True 3 |Ques3|Ans3 |101 |True In the QuesType Table:- QuesTypeID is a Primary key In the Ques Table:- QuesID is a Primary key and QuesType ID is the Foreign Key that refernces QuesTypeID from QuesType Table Now I am unable to delete records from QuesType Table, I can only make QuesType inactive by setting Active=False. I am unable to delete QuesTypes permanently because of the Foreign key relation it has with Ques Table. So , I just set the column Active=false and those Questypes then don't show on my grid wen its binded. What I want to do is be able to delete any QuesType permamnently. Now it can only be deleted if its not being used anywhere in the Ques table, right? So to delete any QuesType permanently I thot this is what I could do:- In the grid that displays QuesTypes, I have this check box for Active and a button for delete.What I thot was, when a user makes some QuesType inactive then OnCheckChanged() event will run and that will have the code to delete all the Questions in Ques table that are using that QuesTypeID. Then on the QuesType grid, that QuesType would show as Deactivated and only then can a user delete it permanently. Am I thinking correctly? Currently in my DeleteQuesType Stored Procedure what I am doing is:- Setting the Active=false and Setting QuesTye= some string like XXInactiveXX Is there any other way?

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  • Load Empty Database table

    - by john White
    I am using SQLexpress and VS2008. I have a DB with a table named "A", which has an IdentitySpecification column named ID. The ID is auto-incremented. Even if the row is deleted, the ID still increases. After several data manipulation, the current ID has reached 15, for example. When I run the application if there's at least 1 row: if I add a new row, the new ID is 16. Everything is fine. If the table is empty (no row): if I add a new row, the new ID is 0, which is an error (I think). And further data manipulation (eg. delete or update) will result in an unhandled exception. Has anyone encountered this? PS. In my table definition, the ID has been selected as follow: Identity Increment = 1; Identity Seed =1; The DB load code is: dataSet = gcnew DataSet(); dataAdapter->Fill(dataSet,"A"); dataTable=dataSet->Tables["A"]; dbConnection->Open(); The Update button method dataAdapter->Update(dataSet,"tblInFlow"); dataSet->AcceptChanges(); dataTable=dataSet->Tables["tblInFlow"]; dataGrid->DataSource=dataTable; If I press Update: if there's at least a row: the datagrid view updates and shows the table correctly. if there's nothing in the table (no data row), the Add method will add a new row, but from ID 0. If I close the program and restart it again: the ID would be 16, which is correct. This is the add method row=dataTable->NewRow(); row["column1"]="something"; dataTable->Rows->Add(row); dataAdapter->Update(dataSet,"A"); dataSet->AcceptChanges(); dataTable=dataSet->Tables["A"];

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  • PL/SQL REGEXP_LIKE testing string for allowed characters

    - by Arino
    I need to verify that the provided string has only allowed characters using Oracle regular expressions (REGEXP_LIKE). Allowed chars are: abcdefghijklmnopqrstuvwxyz0123456789_-. Trying to execute SELECT CASE WHEN REGEXP_LIKE('abcdefghijklmnopqrstuvwxyz0123456789_-.' , '^[a-z0-9_\-\.]+$') THEN 'true' ELSE 'false' END tmp FROM dual; results in 'false'. Any ideas on this?

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  • Having to insert a record, then update the same record warrants 1:1 relationship design?

    - by dianovich
    Let's say an Order has many Line items and we're storing the total cost of an order (based on the sum of prices on order lines) in the orders table. -------------- orders -------------- id ref total_cost -------------- -------------- lines -------------- id order_id price -------------- In a simple application, the order and line are created during the same step of the checkout process. So this means INSERT INTO orders .... -- Get ID of inserted order record INSERT into lines VALUES(null, order_id, ...), ... where we get the order ID after creating the order record. The problem I'm having is trying to figure out the best way to store the total cost of an order. I don't want to have to create an order create lines on an order calculate cost on order based on lines then update record created in 1. in orders table This would mean a nullable total_cost field on orders for starters... My solution thus far is to have an order_totals table with a 1:1 relationship to the orders table. But I think it's redundant. Ideally, since everything required to calculate total costs (lines on an order) is in the database, I would work out the value every time I need it, but this is very expensive. What are your thoughts?

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  • Losing scope for DataContex using LINQToSQL intermediately

    - by greektreat
    I am having a weird Situation with my DataConext. All My code is in C# I have a DLL project for my data access layer and business Layer which and Winforms project for my UI layer. My Data access Layer's Namespace is xxx.Data this is where have my xxx.dbml I also have xxx.Data.BusinessObjects name space of course for my business object in that project In my UI Layer I have these namespaces xxxApp(for Forms), xxxApp.Controls (For Controls) I have lost scope of the DataContext, it was accessible now when I do a Rebuild Solution I sometimes get compile errors saying for example: Error 34 'xxx.Data.xxxDataContext' does not contain a definition for 'SubmitChanges' and no extension method 'SubmitChanges' accepting a first argument of type 'xxx.Data.xxxDataContext' could be found (are you missing a using directive or an assembly reference?) Also intelisense doesn't recognize the methods and table classes from my xxxDataContext anymore I can access all object fine when I am in the DLL project but now in the Winforms project this is very strange. If anyone can help me out I would be extremely grateful!

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  • Highlight row in report?

    - by sanjeev40084
    I have a SSRS report which displays hundred of rows. I was wondering if there is anyway i can highlight the rows so that i can easily know on which row i am while accessing the report. Any thoughts?

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