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  • Linq query with subquery as comma-separated values

    - by Keith
    In my application, a company can have many employees and each employee may have have multiple email addresses. The database schema relates the tables like this: Company - CompanyEmployeeXref - Employee - EmployeeAddressXref - Email I am using Entity Framework and I want to create a LINQ query that returns the name of the company and a comma-separated list of it's employee's email addresses. Here is the query I am attempting: from c in Company join ex in CompanyEmployeeXref on c.Id equals ex.CompanyId join e in Employee on ex.EmployeeId equals e.Id join ax in EmployeeAddressXref on e.Id equals ax.EmployeeId join a in Address on ax.AddressId equals a.Id select new { c.Name, a.Email.Aggregate(x=x + ",") } Desired Output: "Company1", "[email protected],[email protected],[email protected]" "Company2", "[email protected],[email protected],[email protected]" ... I know this code is wrong, I think I'm missing a group by, but it illustrates the point. I'm not sure of the syntax. Is this even possible? Thanks for any help.

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  • NoSql Crash Course/Tutorial

    - by Chris Thompson
    Hi all, I've seen NoSQL pop up quite a bit on SO and I have a solid understanding of why you would use it (from here, Wikipedia, etc). This could be due to the lack of concrete and uniform definition of what it is (more of a paradigm than concrete implementation), but I'm struggling to wrap my head around how I would go about designing a system that would use it or how I would implement it in my system. I'm really stuck in a relational-db mindset thinking of things in terms of tables and joins... At any rate, does anybody know of a crash course/tutorial on a system that would use it (kind of a "hello world" for a NoSQL-based system) or a tutorial that takes an existing "Hello World" app based on SQL and converts it to NoSQL (not necessarily in code, but just a high-level explanation). I see this having one solid answer, but if you guys feel like it should be community wiki, I'll be happy to change it. Thanks! Chris

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  • Should I specify both INDEX and UNIQUE INDEX?

    - by Matt Huggins
    On one of my PostgreSQL tables, I have a set of two fields that will be defined as being unique in the table, but will also both be used together when selecting data. Given this, do I only need to define a UNIQUE INDEX, or should I specify an INDEX in addition to the UNIQUE INDEX? This? CREATE UNIQUE INDEX mytable_col1_col2_idx ON mytable (col1, col2); Or this? CREATE UNIQUE INDEX mytable_col1_col2_uidx ON mytable (col1, col2); CREATE INDEX mytable_col1_col2_idx ON mytable (col1, col2);

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  • Freebase Query with "JOINS"

    - by codemonkey
    ... Yeah, yeah, I know traditional joins don't exist. I actually like the freebase query methodology in theory, just having a little trouble getting it to actually work for me : ) Anyone have a dumb-simple example of getting Freebase data via MQL that pulls from two different "tables"? In particular, I'm trying to get automotive data... so for example, pulling fields from both /automotive/model_year and /automotive/trim_year. I've read the documentation (for hours actually). There's a distinct possibility that I'm looking right at such an example somewhere and just not seeing it because my OLTP brain just doesn't comprehend what it's seeing. * Note * ... that the two "types" I'm working with above are siblings, not parent/child. Does freebase even allow joining data between sibling nodes... I see examples of queries pulling from parent/child, but not from siblings I don't think (or I've overlooked them).

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  • Comparing COUNT values within a query?

    - by outsyncof
    I have the following tables in a relation: person(ssn,sex) employment(ssn,workweeksperyear) assume ssn is a key. My assignment was to do this: Given as input the number of weeks per year a person has worked, determine whether there are more males than females who work more weeks than the input value. SELECT COUNT(sex) AS NumMales FROM person WHERE sex = 'Male' AND ssn IN (SELECT ssn FROM employment WHERE workweeksperyear > 48); The above query gets me the number of males for an input value and I could do the same for number of females but how do I compare the 2 results? Any help will be greatly appreciated!

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  • What 'best practices' exist for handing enum heirarchies?

    - by FerretallicA
    I'm curious as to any solutions out there for addressing enum heirarchies. I'm working through some docs on Entity Framework 4 and trying to apply it to a simple inventory tracking program. The possible types for inventory to fall into are as follows: INVENTORY ITEM TYPES: Hardware PC Desktop Server Laptop Accessory Input (keyboards, scanners etc) Output (monitors, printers etc) Storage (USB sticks, tape drives etc) Communication (network cards, routers etc) Software What recommendations are there for handling enums in a situation like this? Are enums even the solution? I don't really want to have a ridiculously normalised database for such a relatively simple experiment (eg tables for InventoryType, InventorySubtype, InventoryTypeToSubtype etc). I don't really want to over-complicate my data model with each subtype being inherited even though no additional properties or methods are included (except PC types which would ideally have associated accessories and software but that's probably out of scope here). It feels like there should be a really simple, elegant solution to this but I can't put my finger on it. Any assistance or input appreciated!

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  • Hash Table: Should I increase the element count on collisions?

    - by Nazgulled
    Hi, Right now my hash tables count the number of every element inserted into the hash table. I use this count, with the total hash table size, to calculate the load factor and when it reaches like 70%, I rehash it. I was thinking that maybe I should only count the inserted elements with fills an empty slot instead of all of them. Cause the collision method I'm using is separate chaining. The factor load keeps increasing but if there can be a few collisions leaving lots of empty slots on the hash table. You are probably thinking that if I have that many collisions, maybe I'm not using the best hashing method. But that's not the point, I'm using one of the know hashing algorithms out there, I tested 3 of them on my sample data and selected the one who produced less collisions. My question still remains. Should I keep counting every element inserted, or just the ones that fill an empty slot in the Hash Table?

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  • Using a table-alias in Kohana queries?

    - by Aristotle
    I'm trying to run a simple query with $this->db in Kohana, but am running into some syntax issues when I try to use an alias for a table within my query: $result = $this->db ->select("ci.chapter_id, ci.book_id, ci.chapter_heading, ci.chapter_number") ->from("chapter_info ci") ->where(array("ci.chapter_number" => $chapter, "ci.book_id" => $book)) ->get(); It seems to me that this should work just fine. I'm stating that "chapter_info" ought to be known as "ci," yet this isn't taking for some reason. The error is pretty straight-forward: There was an SQL error: Table 'gb_data.chapter_info ci' doesn't exist - SELECT `ci`.`chapter_id`, `ci`.`book_id`, `ci`.`chapter_heading`, `ci`.`chapter_number` FROM (`chapter_info ci`) WHERE `ci`.`chapter_number` = 1 AND `ci`.`book_id` = 1 If I use the full table name, rather than an alias, I get the expected results without error. This requires me to write much more verbose queries, which isn't ideal. Is there some way to use shorter names for tables within Kohana's query-builder?

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  • Working with images in WCF

    - by hgulyan
    Hi, I have a desktop application that needs to upload/download images to/from service computer over TCP Protocol. At first, I stored images in file system, but I need to in MS SQL DB to compare which solution is better. Number of images is over half a million. I don't know yet will there be any limitation on size of a photo. If you have done smth like that, please, write what your opinion upon this question. Which one is faster, more safe? Which of them works better with this number of photos? If I'll store on DB, do I need to store images apart from all other tables which I use for my application and which type works better - image or varbinary on DB?..and so on. Thank you.

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  • Query to return internal details about stored function in SQL Server database

    - by Anthony
    I have been given access to a SQL Server database that is currently used by 3rd party app. As such, I don't have any documentation on how that application stores the data or how it retrieves it. I can figure a few things out based on the names of various tables and the parameters that the user-defined functions takes and returns, but I'm still getting errors at every other turn. I was thinking that it would be really helpful if I could see what the stored functions were doing with the parameters given to return the output. Right now all I've been able to figure out is how to query for the input parameters and the output columns. Is there any built-in information_schema table that will expose what the function is doing between input and output?

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  • Need alternative field names for these reserved words

    - by MattSlay
    “type” and “class” are likely reserved or problematic words in C# and/or Ruby, two languages I may use to program against my new database schema in the future. So, in order to avoid potential conflicts with those languages, I’m looking for alternative names for these field names in my tables. In this case, it is from my Machines table, where I have: “class” field (values would be something like “manual” or “computerized”) and “type” field (values would be “lathe” or “mill”) I could call the fields “machineclass” and “machinetype”, but that is inconsistent with naming scheme in the rest of my schema (meaning, I do not re-use the table name in the field… For instance, I use Machine.name, not Machine.machinename) Any thought on this madness?

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  • Sphinx non-fulltext, integer only search

    - by James
    Hello guys, I've got a few tables that literally only hold integers, no "words" and for some reason Sphinx is unable to hold this data in it's library. Just returns "0 bytes" errors for these indexes. Is it possible to do this? If so, how? Below is an example from my Sphinx.conf for one that fails. source track { type = mysql sql_host = host sql_user = user sql_pass = pass sql_db = db sql_port = port sql_query = SELECT id, user, time FROM track; sql_attr_uint = user sql_attr_uint = time sql_query_info = SELECT * FROM track WHERE id=$id } index track { source = track path = /var/lib/sphinx/track docinfo = extern charset_type = utf-8 min_prefix_len = 1 enable_star = 1 }

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  • MYSQL - Help with a more complicated Query

    - by Joe
    I have two tables: tbl_lists and tbl_houses Inside tbl_lists I have a field called HousesList - it contains the ID's for several houses in the following format: 1# 2# 4# 51# 3# I need to be able to select the mysql fields from tbl_houses WHERE ID = any of those ID's in the list. More specifically, I need to SELECT SUM(tbl_houses.HouseValue) WHERE tbl_houses.ID IN tbl_lists.HousesList -- and I want to do this select to return the SUM for several rows in tbl_lists. Anyone can help? I'm thinking of how I can do this in a SINGLE query since I don't want to do any mysql "loops" (within PHP).

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  • How to run a loop of queries in access?

    - by tksy
    Hi I have a database with a table which is full of conditions and error messages for checking another database. I want to run a loop such that each of these conditions is checked against all the tables in the second database and generae a report which gives the errors. Is this possible in ms access. For example, querycrit table id query error 1 speed<25 and speed>56 speed above limit 2 dist<56 or dist >78 dist within limit I have more than 400 queries like this of different variables. THe table against which I am running the queries is records table id speed dist accce decele aaa bbb ccc 1 33 34 44 33 33 33 33 2 45 44 55 55 55 22 23 regards ttk

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  • Join Query Help

    - by John
    Hello, The query below works well. It pulls data from two MySQL tables, "submission" and "login." I would like to also pull data from a third table called "comment" in the same database. The table "comment" has the following fields: commentid, loginid, submissionid, comment, datecommented Two of the fields in the table "login" are called "loginid" and "username." In the query below, I would like to count all "commentid" in "comment" where "loginid" equals the "loginid" in "login" where "username" equals "$profile." How can I do this? Thanks in advance, John $sqlStr1 = "SELECT l.username, l.loginid, s.loginid, s.submissionid, s.title, s.url, s.datesubmitted, s.displayurl, l.created, count(s.submissionid) countSubmissions FROM submission AS s INNER JOIN login AS l ON s.loginid = l.loginid WHERE l.username = '$profile'";

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  • Interview question - c#

    - by ltech
    I was tasked to conduct my first interview and would like to pose my question to this world for both their feedback on my question and also on their solutions. Question: I have a legacy system with users and files, the info of all files pertaining to a user are stored on a flat file. I want to upgrade this system by storing all info on a db, design tables, and create a C# system that will populate the new db as well as ftp the files to a new path. Define the desgin consideration and develop a prototype. Note: We are looking more for what design one would use and why rather than code that compiles. If it does then kudos to you and we will give it more weight. @Tim C, I did show the interviewee the file: User1234.txt UserID=1234 ParentPath=\\somewhere\nowehere\everywhere\1234 FileCount=20 File0=something0.ext .. File19=something19.ext @Tim C, I have never conducted an interview and I followed a script given to me by my senior developer who was absent.

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  • Can I combine values from multiple rows in another table into multiple columns of one row using SQL?

    - by Jordi
    I have two tables: T1: | M_ID | P_ID1 | P_ID2 | rest of T1 columns | | 0 | 0 | 1 | ... | | 1 | 2 | 3 | ... | T2: | P_ID | Type | A | B | | 0 | 1 | a | e | | 1 | 2 | b | f | | 2 | 1 | c | g | | 3 | 2 | d | h | Now, I want to have a query that selects this: | M_ID | P_1a | P_1b | P_2a | P_2b | rest of T1 columns | | 0 | a | e | b | f | ... | | 1 | c | g | c | h | ... | So, in words: I want to select all columns from T1, but I want to replace P_ID1 with the columns from T2, where the P_ID is equal to P_ID1, and the type is 1, and basically the same for P_ID2. I can obviously get the information I need with multiple queries, but I was wondering if there is a way that I can do this with one query. Any ideas? I'm currently using SQL Server 2008r2, but I'd also be interested in solutions for other database software. Thanks for the help!

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  • Virtual Function Implementation

    - by Gokul
    Hi, I have kept hearing this statement. Switch..Case is Evil for code maintenance, but it provides better performance(since compiler can inline stuffs etc..). Virtual functions are very good for code maintenance, but they incur a performance penalty of two pointer indirections. Say i have a base class with 2 subclasses(X and Y) and one virtual function, so there will be two virtual tables. The object has a pointer, based on which it will choose a virtual table. So for the compiler, it is more like switch( object's function ptr ) { case 0x....: X->call(); break; case 0x....: Y->call(); }; So why should virtual function cost more, if it can get implemented this way, as the compiler can do the same in-lining and other stuff here. Or explain me, why is it decided not to implement the virtual function execution in this way? Thanks, Gokul.

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  • SQL Server 2008 automated database drop, create and fill

    - by lox
    For the database in my project I have a drop/create script for the database, a script for creating tables and SPs and an Access 2003 .mdb file with some exported values. To set up the database from scratch I can use my SQL management studio to first run one script, then the other and lastly manually run the sort of tedious import task. But I would like to do this as automated as possible. Hopefully something like putting the three files in a folder along with a fourth script to execute. Looking something like: run script "dropcreate.sql" run script "createtables.sql" import "values.mdb" How is this done? I hope to avoid using SSIS and the like. The tricky this is of course the import of data, where I can't seem to find a simple way. It is also important that the files a left as they are and not embedded into anything.

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  • SQL Server ORDER BY/WHERE with nested select

    - by Echilon
    I'm trying to get SQL Server to order by a column from a nested select. I know this isn't the best way of doing this but it needs to be done. I have two tables, Bookings and BookingItems. BookingItems contains StartDate and EndDate fields, and there can be multiple BookingItems on a Booking. I need to find the earliest startdate and latest end date from BookingItems, then filter and sort by these values. I've tried with a nested select, but when I try to use one of the selected columns in a WHERE or ORDER BY, I get an "Invalid Column Name". SELECT b.*, (SELECT COUNT(*) FROM bookingitems i WHERE b.BookingID = i.BookingID) AS TotalRooms, (SELECT MIN(i.StartDate) FROM bookingitems i WHERE b.BookingID = i.BookingID) AS StartDate, (SELECT MAX(i.EndDate) FROM bookingitems i WHERE b.BookingID = i.BookingID) AS EndDate FROM bookings b LEFT JOIN customers c ON b.CustomerID = c.CustomerID WHERE StartDate >= '2010-01-01' Am I missing something about SQL ordering? I'm using SQL Server 2008.

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  • Multiple Context menus in PyQt based on mouse location

    - by Nader
    I have a window with multiple tables using QTableWidget (PyQt). I created a popup menu using the right click mouse and it works fine. However, I need to create different popup menu based on which table the mouse is hovering over at the time the right mouse is clicked. How can I get the mouse to tell me which table it is hovering over? or, put in another way, how to implement a method so as to have a specific context menu based on mouse location? I am using Python and PyQt. My popup menu is developed similar to this code (PedroMorgan answer from Qt and context menu): class Foo( QtGui.QWidget ): def __init__(self): QtGui.QWidget.__init__(self, None) # Toolbar toolbar = QtGui.QToolBar() # Actions self.actionAdd = toolbar.addAction("New", self.on_action_add) self.actionEdit = toolbar.addAction("Edit", self.on_action_edit) self.actionDelete = toolbar.addAction("Delete", self.on_action_delete) # Tree self.tree = QtGui.QTreeView() self.tree.setContextMenuPolicy( Qt.CustomContextMenu ) self.connect(self.tree, QtCore.SIGNAL('customContextMenuRequested(const QPoint&)'), self.on_context_menu) # Popup Menu self.popMenu = QtGui.QMenu( self ) self.popMenu.addAction( self.actionEdit ) self.popMenu.addAction( self.actionDelete ) self.popMenu.addSeparator() self.popMenu.addAction( self.actionAdd ) def on_context_menu(self, point): self.popMenu.exec_( self.tree.mapToGlobal(point) )

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  • FTS: Searching across multiple fields 'intelligently'

    - by Wild Thing
    Hi, I have a SP using FTS (Full Text Search). I want searches across multiple fields, 'intelligently' ranking results based on the weights I assign. Consider a search on a view fetching data from tables: Book, Author and Genre. Now, I want the searcher to be able to do: "Ludlum Fiction", "Robert Ludlum Bourne", "Bourne Ludlum", etc. Unfortunately, the only way I have been able to do that at present is this: http://pastebin.com/fdce11ff This is pretty bad, because I am manually breaking up the search string. I know I am doing this completely the wrong way, but can't figure out the right way to search across multiple fields in FTS. Can somebody help please?

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  • sql query question

    - by bu0489
    hey guys, just having a bit of difficulty with a query, i'm trying to figure out how to show the most popular naturopath that has been visited in a centre. My tables look as follows; Patient(patientId, name, gender, DoB, address, state,postcode, homePhone, businessPhone, maritalStatus, occupation, duration,unit, race, registrationDate , GPNo, NaturopathNo) and Naturopath (NaturopathNo, name, contactNo, officeStartTime, officeEndTime, emailAddress) now to query this i've come up with SELECT count(*), naturopathno FROM dbf10.patient WHERE naturopathno != 'NULL' GROUP BY naturopathno; which results in; COUNT(*) NATUROPATH 2 NP5 1 NP6 3 NP2 1 NP1 2 NP3 1 NP7 2 NP8 My question is, how would I go about selecting the highest count from this list, and printing that value with the naturopaths name? Any suggestions are very welcome, Brad

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  • Most optimal order (of joins) for left join

    - by Ram
    I have 3 tables Table1 (with 1020690 records), Table2(with 289425 records), Table 3(with 83692 records).I have something like this SELECT * FROM Table1 T1 /* OK fine select * is bad when not all columns are needed, this is just an example*/ LEFT JOIN Table2 T2 ON T1.id=T2.id LEFT JOIN Table3 T3 ON T1.id=T3.id and a query like this SELECT * FROM Table1 T1 LEFT JOIN Table3 T3 ON T1.id=T3.id LEFT JOIN Table2 T2 ON T1.id=T2.id The query plan shows me that it uses 2 Merge Join for both the joins. For the first query, the first merge is with T1 and T2 and then with T3. For the second query, the first merge is with T1 and T3 and then with T2. Both these queries take about the same time(40 seconds approx.) or sometimes Query1 takes couple of seconds longer. So my question is, does the join order matter ?

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  • username and password check linq query in c#

    - by b0x0rz
    this linq query var users = from u in context.Users where u.UserEMailAdresses.Any(e1 => e1.EMailAddress == userEMail) && u.UserPasswords.Any(e2 => e2.PasswordSaltedHash == passwordSaltedHash) select u; return users.Count(); returns: 1 even when there is nothing in password table. how come? what i am trying to do is get the values of email and passwordHash from two separate tables (UserEMailAddresses and UserPasswords) linked via foreign keys to the third table (Users). it should be simple - checking if email and password mach from form to database. but it is not working for me. i get 1 (for count) even when there are NO entries in the UserPasswords table. is the linq query above completely wrong, or...?

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