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  • MySQL database query returns empty result

    - by user1791096
    I am doing a data migration and getting empty result of simple query with one join. Following is the query Select * from users u INNER JOIN temp_users tu ON tu.uid = u.uid There hundreds of records which have same uid in both tables, but this query returns only one record. Following is the structure of tables users table uid: varchar(50) utf8_general_ci Yes NULL temp_users table uid: varchar(50) utf8_general_ci Yes NULL Is there anyone who faced same problem?

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  • How to manage multiple versions of the same record

    - by Darvis Lombardo
    I am doing short-term contract work for a company that is trying to implement a check-in/check-out type of workflow for their database records. Here's how it should work... 1) A user creates a new entity within the application. There are about 20 related tables that will be populated in addition to the main entity table. 2) Once the entity is created the user will mark it as the master. 3) Another user can make changes to the master only by "checking out" the entity. Multiple users can checkout the entity at the same time. 4) Once the user has made all the necessary changes to the entity, they put it in a "needs approval" status. 5) After an authorized user reviews the entity, they can promote it to master which will put the original record in a tombstoned status. The way they are currently accomplishing the "check out" is by duplicating the entity records in all the tables. The primary keys include EntityID + EntityDate, so they duplicate the entity records in all related tables with the same EntityID and an updated EntityDate and give it a status of "checked out". When the record is put into the next state (needs approval), the duplication occurs again. Eventually it will be promoted to master at which time the final record is marked as master and the original master is marked as dead. This design seems hideous to me, but I understand why they've done it. When someone looks up an entity from within the application, they need to see all current versions of that entity. This was a very straightforward way for making that happen. But the fact that they are representing the same entity multiple times within the same table(s) doesn't sit well with me, nor does the fact that they are duplicating EVERY piece of data rather than only storing deltas. I would be interested in hearing your reaction to the design, whether positive or negative. I would also be grateful for any resoures you can point me to that might be useful for seeing how someone else has implemented such a mechanism. Thanks! Darvis

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  • Is it possible to have a tableless select with multiple rows?

    - by outis
    A SELECT without a FROM clause gets us a multiple columns without querying a table: SELECT 17+23, REPLACE('bannanna', 'nn', 'n'), RAND(), CURRENT_TIMESTAMP; How can we write a query that results in multiple rows without referring to a table? Basically, abuse SELECT to turn it into a data definition statement. The result could have a single column or multiple columns. I'm most interested in a DBMS neutral answer, but others (e.g. based on UNPIVOT) are welcome. There's no technique application behind this question; it's more theoretical than practical.

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  • Databinding multiple tables linq query to gridview?

    - by Curtis White
    My question is how can I display a linq query in a gridview that has data from multiple tables AND allow the user to edit some of the fields or delete the data from a single table? I'd like to do this with either a linqdatasource or a linq query. I'm aware I can set the e.Result to the query on the selecting event. I've also been able to build a custom databound control for displaying the linq relations (parent.child). However, I'm not sure how I can make this work with delete? I'm thinking I may need to handle the delete event with custom code.

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  • C# Getting Just Date From Timestamp

    - by Soo
    If I have a timestamp in the form: yyyy-mm-dd hh:mm:ss:mmm How can I just extract the date from the timestamp? For instance, if a timestamp reads: "2010-05-18 08:36:52:236" what is the best way to just get 2010-05-18 from it. What I'm trying to do is isolate the date portion of the timestamp, define a custom time for it to create a new time stamp. Is there a more efficient way to define the time of the timestamp without first taking out the date, and then adding a new time?

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  • postgresql is incrementing an update by 2 ?

    - by John Tyler
    I'm migrating our model to postgresql for the FTS and data integrity update myschema.counters set counter_count= (counter_count+1) where counter_id =? Works as expected in mysql, however in postgres it is incrementing by 2 each time? It is simple int field I believe, I don't have anything special going on.

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  • MYSQL join - reference external field from nested select?

    - by PHP thinker
    Is it allowed to reference external field from nested select? E.g. SELECT FROM ext1 LEFT JOIN (SELECT * FROM int2 WHERE int2.id = ext1.some_id ) as x ON 1=1 in this case, this is referencing ext1.some_id in nested select. I am getting errors in this case that field ext1.some_id is unknow. Is it possible? Is there some other way?

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  • SYSDATE - 1 error on pl/sql function

    - by ayo
    Hi curtisk/all, I have an issue: when i issue this function below ti gives me the following error: select 'EXECUTE DBMS_LOGMNR.ADD_LOGFILE(LOGFILENAME =>'''||name||'''||,OPTIONS=>DBMS_LOGMNR.NEW);' from v\$archived_log where name is not null; select 'EXECUTE DBMS_LOGMNR.ADD_LOGFILE(LOGFILENAME =>'''||name||'''||,OPTIONS=>DBMS_LOGMNR.ADDFILE);' from v\$archived_log where name is not null; EXECUTE DBMS_LOGMNR.START_LOGMNR( STARTTIME => SYSDATE - 1, ENDTIME => SYSDATE, OPTIONS => DBMS_LOGMNR.DICT_FROM_ONLINE_CATALOG + DBMS_LOGMNR.CONTINUOUS_MINE + DBMS_LOGMNR.COMMITTED_DATA_ONLY + DBMS_LOGMNR.PRINT_PRETTY_SQL); Error: * ERROR at line 1: ORA-01291: missing logfile ORA-06512: at "SYS.DBMS_LOGMNR", line 58 ORA-06512: at line 1 But i have added all the archived logs for several days before and my sysdate is at today. Kindly help out on this issue. thanks. Reagrds Ayo

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  • Validation L2S question

    - by user158020
    This may be a bit winded because I am new to wpf. I have created a partial class for an entity in my L2S class that is primarily used for validation. It implements the onchanging and onvalidate methods. I am trying to use the MVVM pattern, and in a window/view I have set the datacontext in the xaml: <Window.DataContext> <vm:StartViewModel /> </Window.DataContext> when a user leaves a required field in the view blank, the onchanging event of the partial class is fired when I close the form, not when I save the data. So, if a user leaves the textbox blank, the old value is retained and the onchaging method is fired, but I have no idea how to alert the user of the resulting error. here is my onchanging code in the partial class: partial void Ondocument_titleChanging(string value) { if (value.Length == 0) throw new Exception("Document title is required."); if (value.Length > 256) throw new Exception("Document title cannot be longer than 256 characters."); } throwing an exception doesn't notify the user of the error. it just allows the form to close and rejects the changes to the textbox. hope this makes sense... edit: this example was taken from Scott Guthries article here: http://aspalliance.com/1427_LINQ_to_SQL_Part_5__Binding_UI_using_the_ASPLinqDataSource_Control.5

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  • Database indexes - what should they be

    - by WebweaverD
    Most of my database tables have a clear unique index through which lookups are done 90% of the time but I am a bit unsure on this one - I have a table which keeps track of user rating totals for items in my database, I now want to add another table, to track individual ratings with an ip address column to make sure no one can rate something twice. Since I can see this becoming a big, high use table it is important to optimize it correctly. (MYSQL table) This table will have the following fields: rating_id(always - unique), item_id (always - not unique), user_id (optional - not unique), ip_address (always - not unique), rating_value(always - not unique), has_review(bool) Now I envisions 90% the queries going something like this: When a user rates something - select where item_id = x and ip_address = y, (if rows = 0) insert rating When in user account pages - select where ip_address = x or username = y Now none of the fields searched on are unique, can I still use them as indexes (for example item _id and ip_address), can I have two indexes and will this still improve performance over a non indexed table?

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  • Data Access Layer in an ASP.NET website

    - by user3519124
    :) i have a DAL class file in my project, that my teacher sent me and explained to me but i did not really understand it. It has number of functions, and I understand only few of them, like with connecting to the database or creating a command object but there are 2 that I dont understand: public static DataTable GetTable(string str) { OleDbConnection con = DAL.GetConnection(); OleDbCommand cmd = DAL.GetCommand(con, str); DataTable dt = new DataTable(); OleDbDataAdapter adp = new OleDbDataAdapter(); adp.SelectCommand = cmd; adp.Fill(dt); return dt; } public static int ExecuteNonQuery(string str) { int num = -1; OleDbConnection con = DAL.GetConnection(); con.Open(); if (con.State == ConnectionState.Open) { OleDbCommand cmd = DAL.GetCommand(con, str); num = cmd.ExecuteNonQuery(); con.Close(); } return num; } thank you :)

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  • Help with SQL Query

    - by djfrear
    With regards to the following statement: Select * From explorer.booking_record booking_record_ Inner Join explorer.client client_ On booking_record_.labelno = client_.labelno Inner Join explorer.tour_hotel tour_hotel_ On tour_hotel_.tourcode = booking_record_.tourrefcode Inner Join explorer.hotelrecord hotelrecord_ On tour_hotel_.hotelcode = hotelrecord_.hotelref Where booking_record_.bookingdate Not Like '0000-00-00' And booking_record_.tourdeparturedate Not Like '0000-00-00' And hotelrecord_.hotelgroup = "LPL" And Year(booking_record_.tourdeparturedate) Between Year(AddDate(Now(), Interval -5 Year)) And Year(Now()) My MySQL skills are certainly not up to scratch, the actual result set I wish to find is "a customer who has been to 5 or more LPL hotels in the past 5 years". So far I havent got as far as dealing with the count as I'm getting a huge number of results with some 250+ per customer. I assume this is to do with the way I'm joining tables. Schema wise the booking_record table contains a tour reference code, which links to tour_hotel which then contains a hotelcode which links to hotelrecord. This hotelrecord table contains the hotelgroup. The client table is joined to the booking_record via a booking reference and a client may have many bookings. If anyone could suggest a way for me to do this I'd be very grateful and hopefully learn enough to do it myself next time! I've been scratching my head over this one for a few hours now! Customers may have many bookings within booking_record Daniel.

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  • Database layout tagging system

    - by Kurresmack
    I am creating a web site for a customer and they want to be able to create articles. My idea is to tag them so I am going to implement the system. What is the best design, both from an architectural and a perfomance perspective: 1. To have table with all tags and then have a one to many relationship table that links a tag like this: articles table with ID tags table with ID one to many table with columns Article.ID and Tags.ID 2. To have one table with articles and one with tags for articles like this: articles table with ID tags table with Article.ID and tag text Thanks in advance!

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  • Entity Framework Duplicate type name within an assembly (6.1.0)

    - by CodeMilian
    I am not sure what is going on but I keep getting the following exception when doing a query. "Duplicate type name within an assembly." I have not been able to find a solution on the web. I had resolved the issue by removing entity framework from all the projects in the solutions and re-installing using nugget. Then all of the sudden the exception is back. I have verified my table schema over and over and find nothing wrong with. This is the query causing the exception. var BaseQuery = from Users in db.Users join UserInstalls in db.UserTenantInstalls on Users.ID equals UserInstalls.UserID join Installs in db.TenantInstalls on UserInstalls.TenantInstallID equals Installs.ID where Users.Username == Username && Users.Password == Password && Installs.Name == Install select Users; var Query = BaseQuery.Include("UserTenantInstalls.TenantInstall"); return Query.FirstOrDefault(); As I mentioned previously the same query was working before. The data has not changed and the code has not changed.

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  • Hmm, why finding by '2' or '2' return the same record?

    - by SXLee
    Hi everyone, forget my newbie question, but why finding by '2' or '2' in Mysql returns the same record? For example: Say I have a record with string field named 'slug', and the value is '2'. And the following SQLs returns same record. SELECT * From articles WHERE slug='2' SELECT * From articles WHERE slug='2'

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  • How to avoid timestamp issue in a long query?

    - by pingi
    Hi, I have the following 2 tables: items: id int primary key bla text events: id_items int num int when timestamp without time zone ble text composite primary key: id_items, num and want to select to each item the most recent event (the newest 'when'). I wrote an request, but I don't know if it could be written more efficiently. Also on PostgreSQL there is a issue with comparing Timestamp objects: 2010-05-08T10:00:00.123 == 2010-05-08T10:00:00.321 so I select with 'MAX(num)' Any thoughts how to make it better? Thanks. SELECT i.*, ea.* FROM items AS i JOIN ( SELECT t.s AS t_s, t.c AS t_c, max(e.num) AS o FROM events AS e JOIN ( SELECT DISTINCT id_item AS s, MAX(when) AS c FROM events GROUP BY s ORDER BY c ) AS t ON t.s = e.id_item AND e.when = t.c GROUP BY t.s, t.c ) AS tt ON tt.t_s = i.id JOIN events AS ea ON ea.id_item = tt.t_s AND ea.cas = tt.t_c AND ea.num = tt.o;

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  • Complex SQL query, one to many relationship

    - by Ethan
    Hey SO, I have a query such that I need to get A specific dog All comments relating to that dog The user who posted each comment All links to images of the dog the user who posted each link I've tried a several things, and can't figure out quite how to work it. Here's what I have (condensed so you don't have to wade through it all): SELECT s.dog_id, s.name, c.comment, c.date_added AS comment_date_added, u.username AS comment_username, u.user_id AS comment_user_id, l.link AS link, l.date_added AS link_date_added, u2.username AS link_username, u2.user_id AS link_user_id FROM dogs AS d LEFT JOIN comments AS c ON c.dog_id = d.dog_id LEFT JOIN users AS u ON c.user_id = u.user_id LEFT JOIN links AS l ON l.dog_id = d.dog_id LEFT JOIN users AS u2 ON l.user_id = u2.user_id WHERE d.dog_id = '1' It's sorta close to working, but it'll only return me the first comment, and the first link all as one big array with all the info i requested. The are multiple comments and links per dog, so I need it to give me all the comments and all the links. Ideally it'd return an object with dog_id, name, comments(an array of the comments), links(an array of the links) and then comments would have a bunch of comments, date_added, username, and user_id and links would have a bunch of links with link, date_added, username and user_id. It's got to work even if there are no links or comments. I learned the basics of mySQL somewhat recently, but this is pretty far over my head. Any help would be wonderful. Thanks!

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  • Problem with LINQ in C#

    - by David Bonnici
    I am encountering a problem when using LINQ in C#, I am constantly getting "Specified cast is not valid". This is what I am trying to do. I create a class in which I declare all the columns of the table. [Table(Name="tbl_Aff")] public class Affiliate { [Column] public string name; [Column] public string firstname; [Column] public string surname; [Column] public string title; } I then declare a strongly typed DataContext in which I declare all Table collections as members of the context. public partial class Database : DataContext { public Table affiliate; public Database() : base(Settings.getConnectionString()) { } //This method gets the connection string by reading from an XML file. } public partial class Default : System.Web.UI.Page { protected void Page_Load(object sender, EventArgs e) { Database database = new Database(); try { var q = from a in database.affiliate select a; foreach (var aff in q) // Here I get the error "Specified cast is not valid" { lblMessage.InnerHtml += aff.name + ""; } } catch (Exception ex) { System.Console.WriteLine(ex.Message); } } }

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  • Unit testing a SQL code generator

    - by Tom H.
    The team I'm on is currently writing code in TSQL to generate TSQL code that will be saved as scripts and later run. We're having a little difficulty in separating our unit tests between testing the code generator parts and testing the actual code that they generate. I've read through another similar question, but I was hoping to get some specific examples of what kind of unit test cases we might have. As an example, let's say that I have a bit of code that simply generates a DROP statement for a view, given the view schema and name. Do I just test that the generated code matches some expected outcome using string comparisons and then in a later integration or system test make sure that the drop actually drops the view if it exists, does nothing if the view doesn't exist, or raises an error if the view is one that we are marking as not allowing a drop? Thanks for any advice!

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  • Index on column with only 2 distinct values

    - by Will
    I am wondering about the performance of this index: I have an "Invalid" varchar(1) column that has 2 values: NULL or 'Y' I have an index on (invalid), as well as (invalid, last_validated) Last_validated is a datetime (this is used for a unrelated SELECT query) I am flagging a small amount of items (1-5%) of rows in the table with this as 'to be deleted'. This is so when i DELETE FROM items WHERE invalid='Y' it does not perform a full table scan for the invalid items. A problem seems to be, the actual DELETE is quite slow now, possibly because all the indexes are being removed as they are deleted. Would a bitmap index provide better performance for this? or perhaps no index at all?

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  • Does the optimizer filter subqueries with outer where clauses

    - by Mongus Pong
    Take the following query: select * from ( select a, b from c UNION select a, b from d ) where a = 'mung' Will the optimizer generally work out that I am filtering a on the value 'mung' and consequently filter mung on each of the queries in the subquery. OR will it run each query within the subquery union and return the results to the outer query for filtering (as the query would perhaps suggest) In which case the following query would perform better : select * from ( select a, b from c where a = 'mung' UNION select a, b from d where a = 'mung' ) Obviously query 1 is best for maintenance, but is it sacrificing much performace for this? Which is best?

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  • rails: date type and GetDate

    - by cbrulak
    This is a follow up to this question: http://stackoverflow.com/questions/2930256/unique-responses-rails-gem I'm going to create an index based on the user id, url and a date type. I want date type (not datetime type) because I want the day, the 24 hour day to be part of the index to avoid duplication of page views counts on the same day. In other words: A view only counts once in a day by a visitor. I also want the default value of that column (viewdate) to be the function GETDATE(). This is what I have in my migration: execute "ALTER TABLEpage_viewsADD COLUMN viewdate datetime DEFAULTGETDATE()`" But the value viewdate is always empty. What am I missing? (as an aside, any other suggestions for accomplishing this goal?)

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  • Acceessing some aggregate functions in a linq datasource in a GridView

    - by Stephen Pellicer
    I am working on a traditional WebForms project. In the project I am trying out some Linq datasources with plans to eventually migrate to an MVC architecture. I am still very new to Linq. I have a GridView using a Linq datasource. The entities I am showing has a to many relationship and I would like to get the maximum value of a column in the many side of the relationship. I can show properties of the base entity in the gridview: <asp:TemplateField HeaderText="Number" SortExpression="tJobBase.tJob.JobNumber"> <ItemTemplate> <asp:Label ID="Label1" runat="server" Text='<%# Bind("tJobBase.tJob.JobNumber") %>'> </asp:Label> </ItemTemplate> </asp:TemplateField> I can also show the count of the many related property: <asp:TemplateField HeaderText="Number" SortExpression="tJobBase.tJob.tHourlies.Count"> <ItemTemplate> <asp:Label ID="Label1" runat="server" Text='<%# Bind("tJobBase.tJob.tHourlies.Count") %>'> </asp:Label> </ItemTemplate> </asp:TemplateField> Is there a way to get the max value of a column called WeekEnding in the tHourlies collection to show in the GridView?

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  • Active Record/ORM vs Normal Forms?

    - by Arsenal
    Hello, I've been playing around with Active Record a bit, and I have noticed that A.C./ORM always uses the following database model when creating a one-to-one relationship Person id | country_id | name | ... Country id | tld | name | ... No I wondered, isn't this a violiation of the third Normal Form? This clearly states "Every non-prime attribute is non-transitively dependent on every key of the table". Well this country_id isn't dependent of personid is it? So is this wrong or am I just not getting the point?

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