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  • Why is this postgresql query so slow?

    - by user315975
    I'm no database expert, but I have enough knowledge to get myself into trouble, as is the case here. This query SELECT DISTINCT p.* FROM points p, areas a, contacts c WHERE ( p.latitude > 43.6511659465 AND p.latitude < 43.6711659465 AND p.longitude > -79.4677941889 AND p.longitude < -79.4477941889) AND p.resource_type = 'Contact' AND c.user_id = 6 is extremely slow. The points table has fewer than 2000 records, but it takes about 8 seconds to execute. There are indexes on the latitude and longitude columns. Removing the clause concering the resource_type and user_id make no difference. The latitude and longitude fields are both formatted as number(15,10) -- I need the precision for some calculations. There are many, many other queries in this project where points are compared, but no execution time problems. What's going on?

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  • How do I use on delete cascade in mysql?

    - by Marius
    I have a database of components. Each component is of a specific type. That means there is a many-to-one relationship between a component and a type. When I delete a type, I would like to delete all the components which has a foreign key of that type. But if I'm not mistaken, cascade delete will delete the type when the component is deleted. Is there any way to do what I described?

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  • Getting highest results in a JOIN

    - by Keithamus
    I've got three tables; Auctions, Auction Bids and Users. The table structure looks something like this: Auctions: id title -- ----- 1 Auction 1 2 Auction 2 Auction Bids: id user_id auction_id bid_amt -- ------- ---------- ------- 1 1 1 200.00 2 2 1 202.00 3 1 2 100.00 Users is just a standard table, with id and user name. My aim is to join these tables so I can get the highest values of these bids, as well as get the usernames related to those bids; so I have a result set like so: auction_id auction_title auctionbid_amt user_username ---------- ------------- -------------- ------------- 1 Auction 1 202.00 Bidder2 2 Auction 2 100.00 Bidder1 So far my query is as follows: SELECT a.id, a.title, ab.bid_points, u.display_name FROM auction a LEFT JOIN auctionbid ab ON a.id = ab.auction_id LEFT JOIN users u ON u.id = ab.user_id GROUP BY a.id This gets the single rows I am after, but it seems to display the lowest bid_amt, not the highest.

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  • Syntax error in INSERT INTO statement

    - by user454563
    I wrote a program that connects to MS Access. When I fill in the fields and add a new item to Access the program fails. The exception is "Syntax error in INSERT INTO statement" Here is the relevant code. **************************************************************** AdoHelper.cs **************************************************************** using System; using System.Collections.Generic; using System.Text; using System.Data; using System.Data.OleDb; namespace Yad2 { class AdoHelper { //get the connection string from the app.config file //Provider=Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\Yad2.accdb static string connectionString = Properties.Settings.Default.DBConnection.ToString(); //declare the db connection static OleDbConnection con = new OleDbConnection(connectionString); /// <summary> /// To Execute queries which returns result set (table / relation) /// </summary> /// <param name="query">the query string</param> /// <returns></returns> public static DataTable ExecuteDataTable(string query) { try { con.Open(); OleDbCommand command = new OleDbCommand(query, con); System.Data.OleDb.OleDbDataAdapter tableAdapter = new System.Data.OleDb.OleDbDataAdapter(command); DataTable dt = new DataTable(); tableAdapter.Fill(dt); return dt; } catch (Exception ex) { throw ex; } finally { con.Close(); } } /// <summary> /// To Execute update / insert / delete queries /// </summary> /// <param name="query">the query string</param> public static void ExecuteNonQuery(string query) { try { con.Open(); System.Data.OleDb.OleDbCommand command = new System.Data.OleDb.OleDbCommand(query, con); command.ExecuteNonQuery(); } catch (Exception ex) { throw ex; } finally { con.Close(); } } /// <summary> /// To Execute queries which return scalar value /// </summary> /// <param name="query">the query string</param> public static object ExecuteScalar(string query) { try { con.Open(); System.Data.OleDb.OleDbCommand command = new System.Data.OleDb.OleDbCommand(query, con); /// here is the Excaption !!!!!!!!! return command.ExecuteScalar(); } catch { throw; } finally { con.Close(); } } } } **************************************************************************** **************************************************************************** DataQueries.cs **************************************************************************** using System; using System.Collections.Generic; using System.Text; using System.Data; namespace Yad2 { class DataQueries { public static DataTable GetAllItems() { try { string query = "Select * from Messages"; DataTable dt = AdoHelper.ExecuteDataTable(query); return dt; } catch (Exception ex) { throw ex; } } public static void AddNewItem(string mesNumber, string title , string mesDate , string contactMail , string mesType , string Details ) { string query = "Insert into Messages values(" + mesNumber + " , '" + title + "' , '" + mesDate + "' , '" + contactMail + "' , , '" + mesType + "' , '" + Details + "')"; AdoHelper.ExecuteNonQuery(query); } public static void DeleteDept(int mesNumber) { string query = "Delete from Item where MessageNumber=" + mesNumber; AdoHelper.ExecuteNonQuery(query); } } } *********************************************************************************************** plase help me .... why the program falls ?

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  • LINQ Left Join And Right Join

    - by raja
    Hi, I need a help, I have two dataTable called A and B , i need all rows from A and matching row of B Ex: A: B: User | age| Data ID | age|Growth 1 |2 |43.5 1 |2 |46.5 2 |3 |44.5 1 |5 |49.5 3 |4 |45.6 1 |6 |48.5 I need Out Put: User | age| Data |Growth ------------------------ 1 |2 |43.5 |46.5 2 |3 |44.5 | 3 |4 |45.6 |

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  • Why is SQLite3 using covering indices instead of the indices I created?

    - by Geoff
    I have an extremely large database (contacts has ~3 billion entries, people has ~280 million entries, and the other tables have a negligible number of entries). Most other queries I've run are really fast. However, I've encountered a more complicated query that's really slow. I'm wondering if there's any way to speed this up. First of all, here is my schema: CREATE TABLE activities (id INTEGER PRIMARY KEY, name TEXT NOT NULL); CREATE TABLE contacts ( id INTEGER PRIMARY KEY, person1_id INTEGER NOT NULL, person2_id INTEGER NOT NULL, duration REAL NOT NULL, -- hours activity_id INTEGER NOT NULL -- FOREIGN_KEY(person1_id) REFERENCES people(id), -- FOREIGN_KEY(person2_id) REFERENCES people(id) ); CREATE TABLE people ( id INTEGER PRIMARY KEY, state_id INTEGER NOT NULL, county_id INTEGER NOT NULL, age INTEGER NOT NULL, gender TEXT NOT NULL, -- M or F income INTEGER NOT NULL -- FOREIGN_KEY(state_id) REFERENCES states(id) ); CREATE TABLE states ( id INTEGER PRIMARY KEY, name TEXT NOT NULL, abbreviation TEXT NOT NULL ); CREATE INDEX activities_name_index on activities(name); CREATE INDEX contacts_activity_id_index on contacts(activity_id); CREATE INDEX contacts_duration_index on contacts(duration); CREATE INDEX contacts_person1_id_index on contacts(person1_id); CREATE INDEX contacts_person2_id_index on contacts(person2_id); CREATE INDEX people_age_index on people(age); CREATE INDEX people_county_id_index on people(county_id); CREATE INDEX people_gender_index on people(gender); CREATE INDEX people_income_index on people(income); CREATE INDEX people_state_id_index on people(state_id); CREATE INDEX states_abbreviation_index on states(abbreviation); CREATE INDEX states_name_index on states(name); Note that I've created an index on every column in the database. I don't care about the size of the database; speed is all I care about. Here's an example of a query that, as expected, runs almost instantly: SELECT count(*) FROM people, states WHERE people.state_id=states.id and states.abbreviation='IA'; Here's the troublesome query: SELECT * FROM contacts WHERE rowid IN (SELECT contacts.rowid FROM contacts, people, states WHERE contacts.person1_id=people.id AND people.state_id=states.id AND states.name='Kansas' INTERSECT SELECT contacts.rowid FROM contacts, people, states WHERE contacts.person2_id=people.id AND people.state_id=states.id AND states.name='Missouri'); Now, what I think would happen is that each subquery would use each relevant index I've created to speed this up. However, when I show the query plan, I see this: sqlite> EXPLAIN QUERY PLAN SELECT * FROM contacts WHERE rowid IN (SELECT contacts.rowid FROM contacts, people, states WHERE contacts.person1_id=people.id AND people.state_id=states.id AND states.name='Kansas' INTERSECT SELECT contacts.rowid FROM contacts, people, states WHERE contacts.person2_id=people.id AND people.state_id=states.id AND states.name='Missouri'); 0|0|0|SEARCH TABLE contacts USING INTEGER PRIMARY KEY (rowid=?) (~25 rows) 0|0|0|EXECUTE LIST SUBQUERY 1 2|0|2|SEARCH TABLE states USING COVERING INDEX states_name_index (name=?) (~1 rows) 2|1|1|SEARCH TABLE people USING COVERING INDEX people_state_id_index (state_id=?) (~5569556 rows) 2|2|0|SEARCH TABLE contacts USING COVERING INDEX contacts_person1_id_index (person1_id=?) (~12 rows) 3|0|2|SEARCH TABLE states USING COVERING INDEX states_name_index (name=?) (~1 rows) 3|1|1|SEARCH TABLE people USING COVERING INDEX people_state_id_index (state_id=?) (~5569556 rows) 3|2|0|SEARCH TABLE contacts USING COVERING INDEX contacts_person2_id_index (person2_id=?) (~12 rows) 1|0|0|COMPOUND SUBQUERIES 2 AND 3 USING TEMP B-TREE (INTERSECT) In fact, if I show the query plan for the first query I posted, I get this: sqlite> EXPLAIN QUERY PLAN SELECT count(*) FROM people, states WHERE people.state_id=states.id and states.abbreviation='IA'; 0|0|1|SEARCH TABLE states USING COVERING INDEX states_abbreviation_index (abbreviation=?) (~1 rows) 0|1|0|SEARCH TABLE people USING COVERING INDEX people_state_id_index (state_id=?) (~5569556 rows) Why is SQLite using covering indices instead of the indices I created? Shouldn't the search in the people table be able to happen in log(n) time given state_id which in turn is found in log(n) time?

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  • How would I associate a "Note" class to 4+ classes without creating lookup table for each associatio

    - by Gthompson83
    Im creating a project tasklist application. I have project, section, task, issue classes, and would like to use one class to be able to add simple notes to any object instance of those classes. The task, issue tables both use a standard identity field as a primary key. The section table has a two field primary key. The project table has a single int primary key defined by the user. Is there a way to associate the note class with each of these without using a seperate lookup table for each class? I'm not so sure my original idea is a decent way to implement this. I considered the following (each variable mapping to a field n the notes table. Private _NoteId As Integer Private _ProjectId As Integer Private _SectionId As Integer Private _SectionId2 As Integer Private _TaskId As Integer Private _IssueId As Integer Private _Note As String Private _UserId As Guid Then I would be able to write seperate methods (getProjectNotes, getTaskNotes) to get notes attached to each class. I started writing this a few weeks ago but got pulled away before i could finish. When revisiting this code today my first thought "this is retarded". Thoughts on drawbacks to this design?

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  • How to check with PHP does a SQL database already have

    - by Dan Horvat
    I've tried to find the answer to this question but none of the answers fit. I have two databases, one has 15.000.000 entries and I want to extract the necessary data and store it in a much smaller database with around 33.000 entries. Both databases are open at the same time. Or at least they should be. While having the big database open and extracting the entries from it, is it possible to check whether the value already exists in the smaller database? I just need some generic way which checks that.

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  • mySQL: Order by field size/length

    - by Sadi
    Here is a table structure (e.g. test): __________________________________________ | Field Name | Data Type | |________________|_________________________| | id | BIGINT (20) | |________________|_________________________| | title | varchar(25) | |________________|_________________________| | description | text | |________________|_________________________| A query like: SELECT * FROM TEST ORDER BY description; But I would like to order by the field size/length of the field description. The field type will be TEXT or BLOB.

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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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  • LESS THAN OR EQUAL TO IN Oracle SQL

    - by Jasim
    updated_date = 08-Jun-2010; I have a query like this select * from asd whre updated_date <= todate('08-Jun-2010', 'dd-MM-yy'); but i am not getting any result. it is wotking only if todate is 09-Jun-2010... ie my equalto operator is not working properly. y is it like that ny help?

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  • Select where and where not

    - by Simon
    I have a table containing lessons that I called "cours" (french) and I have several cours inside and I have linked them to students with a table between them to see if they go to the lessons or not. I would like to return data with the SELECT and the data that are NOT select. So, If one student follow 3 courses of 5, I would like to return the 3 courses that he follow and the 2 courses that he doesn't follow. Is there a way to do it ?

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  • SSRS 2005 Keep textbox and textfield together when page break occurs

    - by EKet
    Problem I don't have a details row or anything. I have simply a body and I dragged on textboxes for labeling textfields from my dataset. The problem is when one of the fields has too much data for the current page, it "page-breaks" at the start of the field leaving the textbox (label for the field) behind on the previous page. What I've tried Put the data field and the textbox label a) inside a rectangle - didn't work b) inside a list and the list inside a rectangle - didn't work c) inside a list with keep together property set to TRUE or FALSE - didn't work Question How would I group the textbox and the textfield so that regardless of where the pagebreak happens it includes its label?

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  • [C#] How to create a constructor of a class that return a collection of instances of that class?

    - by codemonkie
    My program has the following class definition: public sealed class Subscriber { private subscription; public Subscriber(int id) { using (DataContext dc = new DataContext()) { this.subscription = dc._GetSubscription(id).SingleOrDefault(); } } } ,where _GetSubscription() is a sproc which returns a value of type ISingleResult<_GetSubscriptionResult> Say, I have a list of type List<int> full of 1000 ids and I want to create a collection of subscribers of type List<Subscriber>. How can I do that without calling the constructor in a loop for 1000 times? Since I am trying to avoid switching the DataContext on/off so frequently that may stress the database. TIA.

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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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  • 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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  • Advantages of SQLServer vs. MySQL for C#/.NET4 Cloud Applications

    - by Ed Eichman
    I am considering building several C#/.NET4 applications all using a central, cloud based database. In addition, several LAMP (MySQL) web shops will be accessing the cloud DB. MySQL is the database that I'm most familiar with, and my default selection for the cloud DB would be MySQL on Amazon or Joyent. However, I was wondering what development "extras" are available for SQLServer in VisualStudio 2010 that are not available for MySQL. Are there any "killer features" that should make me consider SQLServer instead of MySQL?

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  • Violation of primary key constraint, multiple users

    - by MC.
    Lets say UserA and UserB both have an application open and are working with the same type of data. UserA inserts a record into the table with value 10 (PrimaryKey='A'), UserB does not currently see the value UserA entered and attempts to insert a new value of 20 (PrimaryKey='A'). What I wanted in this situation was a DBConcurrencyException, but instead what I have is a primary key violation. I understand why, but I have no idea how to resolve this. What is a good practice to deal with such a circumstance? I do not want to merge before updating the database because I want an error to inform the user that multiple users updated this data.

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  • Need to use query column value in nested subquery

    - by Dustin
    It seems I cannot use a column from the parent query in a sub query. How can I refactor this query to get what I need? dbo.func_getRelatedAcnts returns a table of related accounts (all children from a given account). Events and Profiles are related to accounts. SELECT COUNT(r.reg_id) FROM registrations r JOIN profiles p ON (r.reg_frn_pro_id = p.pro_id) JOIN events e ON (r.reg_frn_evt_id = e.evt_id) WHERE evt_frn_acnt_id NOT IN (SELECT * FROM dbo.func_getRelatedAcnts(p.pro_frn_acnt_id))

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