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  • How do I drop a foerign key in mssql?

    - by mmattax
    I have created a foreign key (in mssql / tsql) by: alter table company add CountryID varchar(3); alter table company add constraint Company_CountryID_FK foreign key(CountryID) references Country; I then run this query: alter table company drop column CountryID; and I get this error: Msg 5074, Level 16, State 4, Line 2 The object 'Company_CountryID_FK' is dependent on column 'CountryID'. Msg 4922, Level 16, State 9, Line 2 ALTER TABLE DROP COLUMN CountryID failed because one or more objects access this column. I have tried this, yet it does not seem to work: alter table company drop foreign key Company_CountryID_FK; alter table company drop column CountryID; What do I need to do to drop the CountryID column? Thanks.

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  • Suggestion on Database structure for relational data

    - by miccet
    Hi there. I've been wrestling with this problem for quite a while now and the automatic mails with 'Slow Query' warnings are still popping in. Basically, I have Blogs with a corresponding table as well as a table that keeps track of how many times each Blog has been viewed. This last table has a huge amount of records since this page is relatively high traffic and it logs every hit as an individual row. I have tried with indexes on the fields that are included in the WHERE clause, but it doesn't seem to help. I have also tried to clean the table each week by removing old ( 1.weeks) records. SO, I'm asking you guys, how would you solve this? The query that I know is causing the slowness is generated by Rails and looks like this: SELECT count(*) AS count_all FROM blog_views WHERE (created_at >= '2010-01-01 00:00:01' AND blog_id = 1); The tables have the following structures: CREATE TABLE IF NOT EXISTS 'blogs' ( 'id' int(11) NOT NULL auto_increment, 'name' varchar(255) default NULL, 'perma_name' varchar(255) default NULL, 'author_id' int(11) default NULL, 'created_at' datetime default NULL, 'updated_at' datetime default NULL, 'blog_picture_id' int(11) default NULL, 'blog_picture2_id' int(11) default NULL, 'page_id' int(11) default NULL, 'blog_picture3_id' int(11) default NULL, 'active' tinyint(1) default '1', PRIMARY KEY ('id'), KEY 'index_blogs_on_author_id' ('author_id') ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ; And CREATE TABLE IF NOT EXISTS 'blog_views' ( 'id' int(11) NOT NULL auto_increment, 'blog_id' int(11) default NULL, 'ip' varchar(255) default NULL, 'created_at' datetime default NULL, 'updated_at' datetime default NULL, PRIMARY KEY ('id'), KEY 'index_blog_views_on_blog_id' ('blog_id'), KEY 'created_at' ('created_at') ) ENGINE=InnoDB DEFAULT CHARSET=utf8 AUTO_INCREMENT=1 ;

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  • best database design for city zip & state tables

    - by ryan a
    My application will need to reference addresses. Street info will be stored with my main objects but the rest needs to be stored seperately to reduce redundancy. How should I store/retrieve ZIPs, cities and states? Here are some of my ideas. single table solution (cant do relationships) [locations] locationID locationParent (FK for locationID - 0 for state entries) locationName (city, state) locationZIP two tables (with relationships, FK constraints, ref integrity) [state] stateID stateName [city] cityID stateID (FK for state.stateID) cityName zipCode three tables [state] stateID stateName [city] cityID stateID (FK for state.stateID) cityName [zip] zipID cityID (FK for city.cityID) zipName Then I read into ZIP codes amd how they are assigned. They aren't specifically related to cities. Some cities have more than one ZIP (ok will still work) but some ZIPs are in more than one city (oh snap) and some other ZIPs (very few) are in more than one state! Also some ZIPs are not even in the same state as the address they belong to at all. Seems ZIPs are made for carrier route identification and some remote places are best served by post offices in neighboring cities or states. Does anybody know of a good (not perfect) solution that takes this into consideration to minimize discrepencies as the database grows?

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  • how to debug a query that has valid syntax, executes, but returns no results?

    - by Ty W
    So I'm writing a fairly involved query with a half dozen joins, a dependent subquery for [greatest-n-per-group] purposes, grouping, etc. It is syntactically valid, but I've clearly made at least one mistake because it returns nothing. In the past I've debugged valid queries that return nothing by removing joins, executing subqueries on their own, removing WHERE conditions, and removing grouping to see what I would get but so far this one has me stumped. Are there better tools or techniques to use for this sort of thing? This particular query is for MySQL if it matters for any platform-specific tools.

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  • what's the performance difference between int and varchar for primary keys

    - by user568576
    I need to create a primary key scheme for a system that will need peer to peer replication. So I'm planning to combine a unique system ID and a sequential number in some way to come up with unique ID's. I want to make sure I'll never run out of ID's, so I'm thinking about using a varchar field, since I could always add another character if I start running out. But I've read that integers are better optimized for this. So I have some questions... 1) Are integers really better optimized? And if they are, how much of a performance difference is there between varchars and integers? I'm going to use firebird for now. But I may switch later. Or possibly support multiple db's. So I'm looking for generalizations, if that's possible. 2) If integers are significantly better optimized, why is that? And is it likely that varchars will catch up in the future, so eventually it won't matter anyway? My varchar keys won't have any meaning, except for the unique system ID part. But I may want to obscure that somehow. Also, I plan to efficiently use all the bits of each character. I don't, for example, plan to code the integer 123 as the character string "123". So I don't think varchars will require more space than integers.

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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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  • Designing a table to store EXIF data

    - by rafale
    I'm looking to get the best performance out of querying a table containing EXIF data. The queries in question will only search the EXIF data for the specified strings and return the row index on a match. With that said, would it better to store the EXIF data in a table with separate columns for each of the tags, or would storing all of the tags in a single column as one long delimited string suit me just as well? There are around 115 EXIF tags I'll be storing, and each record would be around 1500 to 2000 chars in length if concatenated into a single string.

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  • Should I use DATE and TIME as fields rather than DATETIME

    - by whitstone86
    I have a project on going for a TV guide, called mytvguide in the database - I use PHPMyAdmin. This is the structure for one table, which is called tvshow1: Field Type channel varchar(255) date date No airdate time No expiration time No episode varchar(255) setreminder varchar(255) but am not sure how to get DATE, TIME to work with the pagination script (below is the script, which works for the version with DATETIME): http://pastebin.com/6S1ejAFJ However, although the DATETIME one works - it shows programmes that air on the day itself like this: Programme 1 showing on Channel 1 2:35pm "Episode 2" Set Reminder Programme 1 showing on Channel 1 May 26th - 12:50pm "Episode 3" Set Reminder Programme 1 showing on Channel 1 May 26th - 5:55pm "Episode 3" Set Reminder but I'm not quite sure how to replicate that for the fields that use DATE, TIME functions as seen above. Any advice on this is appreciated, thanks!

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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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  • SqlException: Login failed for user

    - by Younes
    I use a dbml for my Data Access Layer to provide the data that i need in my app. When i connect from the server explorer everything seems fine. I choose to use my windows authentication and the connection test shows everything works just fine. When i Build my solution and run it on my IIS it says that i'm using a login that is not working. How to solve this issue?

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  • Which would be better? Storing/access data in a local text file, or in a database?

    - by TerranRich
    Basically, I'm still working on a puzzle-related website (micro-site really), and I'm making a tool that lets you input a word pattern (e.g. "r??n") and get all the matching words (in this case: rain, rein, ruin, etc.). Should I store the words in local text files (such as words5.txt, which would have a return-delimited list of 5-letter words), or in a database (such as the table Words5, which would again store 5-letter words)? I'm looking at the problem in terms of data retrieval speeds and CPU server load. I could definitely try it both ways and record the times taken for several runs with both methods, but I'd rather hear it from people who might have had experience with this. Which method is generally better overall?

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  • Group and count in Rails

    - by alamodey
    I have this bit of code and I get an empty object. @results = PollRoles.find( :all, :select => 'option_id, count(*) count', :group => 'option_id', :conditions => ["poll_id = ?", @poll.id]) Is this the correct way of writing the query? I want a collection of records that have an option id and the number of times that option id is found in the PollRoles model. EDIT: This is how I''m iterating through the results: <% @results.each do |result| %> <% @option = Option.find_by_id(result.option_id) %> <%= @option.question %> <%= result.count %> <% end %>

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  • Syntax Error in showing Error Description

    - by Sreejesh Kumar
    What is the correct Syntax to be applied for "@[System::ErrorDescription]" inside the query like "INSERT" ? I am unable to retrieve the correct Error Description inside the table, as the result in the table is showing as "@[System::ErrorDescription]". I am not getting the result !

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  • jpa join query on a subclass

    - by Brian
    I have the following relationships in JPA (hibernate). Object X has two subclasses, Y and Z. Object A has a manyToOne relationship to object X. (Note, this is a one-sided relationship so object X cannot see object A). Now, I want to get the max value of a column in object A, but only where the relationship is of a specific subtype, ie...Y. So, that equates to...get the max value of column1 in object A, across all instances of A where they have a relationship with Y. Is this possible? I'm a bit lost as how to query it. I was thinking of something like: String query = "SELECT MAX(a.columnName) FROM A a join a.x; Query query = super.entityManager.createQuery(query); query.execute(); However that doesn't take account of the subclass of X...so I'm a bit lost. Any help would be much appreciated.

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  • How can I bind an Enum to a DbType of bit or int?

    - by uriDium
    Hi I am using Linq2Sql and want to bind an objects field (which is enum) to either a bit or a int type in the database. For example I want have a gender field in my model. I have already edited the DBML and changed the Type to point to my enum. I want to create Radio buttons (which I think I have figured out) for gender and dropdown lists for other areas using the same idea. My enum looks like this public enum Gender { Male, Female } Mapping between DbType 'int' and Type 'Project.Models.Gender' in Column 'Gender' of Type 'Candidate' is not supported. Any ideas on how to do this mapping. Am I missing something on the enums.

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  • how to write this query using joins?

    - by aquero
    Hi, i have a table campaign which has details of campaign mails sent. campaign_table: campaign_id campaign_name flag 1 test1 1 2 test2 1 3 test3 0 another table campaign activity which has details of campaign activities. campaign_activity: campaign_id is_clicked is_opened 1 0 1 1 1 0 2 0 1 2 1 0 I want to get all campaigns with flag value 3 and the number of is_clicked columns with value 1 and number of columns with is_opened value 1 in a single query. ie. campaign_id campaign_name numberofclicks numberofopens 1 test1 1 1 2 test2 1 1 I did this using sub-query with the query: select c.campaign_id,c.campaign_name, (SELECT count(campaign_id) from campaign_activity WHERE campaign_id=c.id AND is_clicked=1) as numberofclicks, (SELECT count(campaign_id) from campaign_activity WHERE campaign_id=c.id AND is_clicked=1) as numberofopens FROM campaign c WHERE c.flag=1 But people say that using sub-queries are not a good coding convention and you have to use join instead of sub-queries. But i don't know how to get the same result using join. I consulted with some of my colleagues and they are saying that its not possible to use join in this situation. Is it possible to get the same result using joins? if yes, please tell me how.

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  • How to retrieve last primary Id from mdb's table?

    - by William
    I got table with next columns: Id, Name, Age, Class I am trying to insert new row in db like this: INSERT INTO MyTable (Name, Age, Class) VALUES (@name, @age, @class) And get an exeption: "Index or primary key cannot contain a Null value." The question is how to add a new row without knowing next primary Id, or maybe there is a way to get this Id from the table with the help of another query ?

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  • Showing multiple models in a single ListView

    - by Veer
    I've three models (Contacts, Notes, Reminders). I want to search all these and produce the filtered result in a single listview and depending upon the selection I've to display the corresponding view(UserControl) to its right. I want the right way of implementing the design or atleast alternatives to this method that I've tried. Now I've tried it using a IntegratedViewModel having all the properties from all the three models. public class IntegratedViewModel { ContactModel _contactModel; NoteModel _noteModel; public IntegratedViewModel(ContactModel contactModel) { _contactModel = contactModel; } // similarly for other models also public string DisplayTitle // For displaying in ListView { get; //same as set set { If(_contactModel != null) return _contactModel.Name; If(_noteModel != null) return _noteModel.Title; } } // All other properties from the three models includin the Name/Title properties for displaying them in the corresponding views(UserControl) } Now I set the itemsSource as the List<IntegratedViewModel>. I've to now bind the visibility of the views to some properties in the MainViewModel. I tried setting bool properties like IsContactViewSelected, IsNoteViewSelected using the setter of SelectedEntity property which is bound to the ListView's SelectedItem. public SelectedEntity { //get set { oldvalue = _selectedEntity; _selectedEntity = value; // now i find the Type of model selected using oldvalue.ModelType // where ModelType is a property in the IntegratedViewModel // according to the type, i set one of the above bool properties to false // and do the same for _selectedEntity but set the property to true // so that the view corresponding to the selectedEntityType is visible // and others are collapsed } } Here is the problem: For eg: let us say, I selected an item of type ContactModel, the old selection being NoteModel. I set the property IsNoteModelSelected to false according to the oldvalue, it sets the property and then Raises the propertychanged event and does not go and check the remaining if condition where i check for _selectedEntity which is used to set the IsContactModelSelected to true.

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  • Why is Postgres doing a Hash in this query?

    - by Claudiu
    I have two tables: A and P. I want to get information out of all rows in A whose id is in a temporary table I created, tmp_ids. However, there is additional information about A in the P table, foo, and I want to get this info as well. I have the following query: SELECT A.H_id AS hid, A.id AS aid, P.foo, A.pos, A.size FROM tmp_ids, P, A WHERE tmp_ids.id = A.H_id AND P.id = A.P_id I noticed it going slowly, and when I asked Postgres to explain, I noticed that it combines tmp_ids with an index on A I created for H_id with a nested loop. However, it hashes all of P before doing a Hash join with the result of the first merge. P is quite large and I think this is what's taking all the time. Why would it create a hash there? P.id is P's primary key, and A.P_id has an index of its own.

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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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