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• How to use SOCI C++ Database library?

  - by NeDark

  I'm trying to implement soci in my program but I don't know how. I'm using C++ on linux, on a project on netbeans. I have followed the steps in http://soci.sourceforge.net/doc/structure.html to install it, and I tried to copy the files soci.h from /src/core and soci-mysql.h from /src/backends/mysql in my proyect but it gives compilation error (these files include other soci files, but it's illogical to copy all files into the directory...). I have read the guide several time but I don't understand what I'm doing wrong, the examples only include these files. Thanks. Edit: I have given more information in a comment below the answer. I don't know what steps I have to do to implement soci.

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• database assignment

  - by eric

  Hi, Given the following table: CREATE TABLE T1 (A INTEGER NOT NULL); CREATE TABLE T3 (A SMALLINT NOT NULL); INSERT T1 VALUES (32768.5); SELECT * FROM T1; INSERT T3 SELECT * FROM T1; SELECT * FROM T3; What is the output of above query? If any error occured please declare the line of it?Explain your answer!

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• How to organise a many to many relationship in MongoDB

  - by Gareth Elms

  I have two tables/collections; Users and Groups. A user can be a member of any number of groups and a user can also be an owner of any number of groups. In a relational database I'd probably have a third table called UserGroups with a UserID column, a GroupID column and an IsOwner column. I'm using MongoDB and I'm sure there is a different approach for this kind of relationship in a document database. Should I embed the list of groups and groups-as-owner inside the Users table as two arrays of ObjectIDs? Should I also store the list of members and owners in the Groups table as two arrays, effectively mirroring the relationship causing a duplication of relationship information? Or is a bridging UserGroups table a legitimate concept in document databases for many to many relationships? Thanks

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• Generating text file from database

  - by Goldmember

  I have a requirement to hand-code an text file from data residing in a SQL table. Just wondering if there are any best practices here. Should I write it as an XMLDocument first and transform using XSL or just use Streamwriter and skip transformation altogether? The generated text file will be in EDIFACT format, so layout is very specific.

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• database transaction rollback processing in PHP

  - by user198729

  try { $con->beginTransaction(); $this->doSave($con); $con->commit(); } catch (Exception $e) { $con->rollBack(); throw $e; } The code above is quite standard an approach to deal with transactions, but my question is:what if $con->rollBack() also fails? It may cause db lock,right?If so,what's the perfect way to go?

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• database table design

  - by e.b.white

  I design the tables as below for the system which looks like a package delivering system For example, after user received the package, postman should record in system, and the state(history table) is "delivered",and operator is this postman, the current state(state table) is of course "delivered" history table: +---------------+--------------------------+ | Field | Desc | +---------------+--------------------------+ | id | PRIMARY KEY | +---------------+--------------------------+ | package_id | package_tacking_id | +---------------+--------------------------+ | state | package_state | +---------------+--------------------------+ | operators | operators | +---------------+--------------------------+ | create_time| create_time | +---------------+--------------------------+ state table: +---------------+--------------------------+ | Field | Desc | +---------------+--------------------------+ | id | PRIMARY KEY | +---------------+--------------------------+ | package_id | package_tacking_id | +---------------+--------------------------+ | state | latest_package_state | +---------------+--------------------------+ Above is just the basic information to record, some other information( like invoice, destination,...) should be recored as well. But there are different service types like s1 and s2, for s1 it is not needed to record invoice but s1 need, and maybe s1 need some other information to record (like the tel of end user). After all, at delivering way stations there are additional information to record, and for different service type the information type is different. My question is: 1. For different service type, shall I need to declare different tables(option A) or just one big table which can record all information for all types(option B)? 2. If option A, since the basic information above is MUST, how can prevent from declaring there duplicate fields in different tables?

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• Query scope within a table trigger in an Oracle database

  - by sisslack

  I'm been trying to write a table trigger the queries another table that is outside the schema where the trigger will reside. Is this possible? It seems like I have no problem querying tables in my schema but I get: Error: ORA-00942: table or view does not exist when trying trying to query tables outside my schema. The documentation seems to elude to this notion, but it's not 100% clear to me.

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• Database model for storing expressions and their occurrence in text

  - by lisak

  Hey, I'm doing a statistical research application. I need to store words according to 2 initial letters which is 676 combinations and each word has its number of occurrences (minimal, maximal, average) in text. I'm not sure how the model/schema should look like. There will be a lot of checking whether the keyword was already persisted. I appreciate your suggestions. Edit: I'll be using either mysql or postgresql + spring templates

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• Database design -- does it respect 3rd NF?

  - by Flavius

  Hi I have the following relations (tables) in a relational model Person person_id, first_name, last_name, address Student person_id, matr_nr Teacher person_id, salary Lecture lecture_id, lect_name, lect_description Attendees lecture_id, person_id, date I'm wondering about the functional dependencies of Student and Teacher. Do these tables respect the 3rd normal form? Which should be the primary keys of these tables?

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• Unstructured database design

  - by Linh

  Hi all, According to normal way, we design the table with fields. Example with an article the table can contain fields as follows: title, content, author..... But how does everybody think if we add up some fields to a field?

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• Generic Database table design

  - by Gazeth

  Just trying to figure out the best way to design my table for the following scenario: I have several areas in my system (documents, projects, groups and clients) and each of these can have comments logged against them. My question is should I have one table like this: CommentID DocumentID ProjectID GroupID ClientID etc Where only one of the ids will have data and the rest will be NULL or should I have a seperate CommentType table and have my comments table like this: CommentID CommentTypeID ResourceID (this being the id of the project/doc/client) etc My thoughts are that option 2 would be more efficient from an indexing point of view?

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• Sorting nested set by name while keep depth integrity

  - by wb

  I'm using the nested set model that'll later be used to build a sitemap for my web site. This is my table structure. create table departments ( id int identity(0, 1) primary key , lft int , rgt int , name nvarchar(60) ); insert into departments (lft, rgt, name) values (1, 10, 'departments'); insert into departments (lft, rgt, name) values (2, 3, 'd'); insert into departments (lft, rgt, name) values (4, 9, 'a'); insert into departments (lft, rgt, name) values (5, 6, 'b'); insert into departments (lft, rgt, name) values (7, 8, 'c'); How can I sort by depth as well as name? I can do select replicate('----', count(parent.name) - 1) + ' ' + node.name , count(parent.name) - 1 as depth , node.lft from departments node , departments parent where node.lft between parent.lft and parent.rgt group by node.name, node.lft order by depth asc, node.name asc; However, that does not match children with their parent for some reason. department lft rgt --------------------------- departments 0 1 ---- a 1 4 ---- d 1 2 -------- b 2 5 -------- c 2 7 As you can see, department 'd' has department 'a's children! Thank you.

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• Lookups in Multi-Tenant Database

  - by Huthaifa Afanah

  I am developing a SaaS application and I am looking for the best way to design lookup tables, taking in consideration: The look-up tables will have predefined data shared among all the tenants Each tenant must have the ability to extend the look-up table with his own data e.g adding a car class not defined I am thinking about adding TenantID column to each lookup and add the predefined data with setting that column to some value which represents the "Super Tenant" that belongs to the system itself

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• Customers and suppliers database design issue

  - by hectorsq

  I am developing a web application in which I will have customers and suppliers. Initially I thought on using a Customers table and a Suppliers table. Then when I was thinking on bank transactions, I noticed that each transaction needs to refer to a customer or a supplier, so I thought on using a single table named Business in which I will save both customers and suppliers. If I use Customers and Suppliers tables when I want to list the bank transactions I will have to search in both tables to get the company name. If I use a Businesses table I will have to use a business type column, and have the union of possible fields for all businesses types. Any suggestions on the design?

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• Database persistence without an SQL server

  - by James P.

  I'm seeking a solution that would allow persistence without requiring an SQL server to be installed on the host and could be bundled along with a desktop application. Does such a thing exist?

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• Voting Script, Possiblity 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

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• Comma separated values in a database field

  - by John Doe

  I have a products table. Each row in that table corresponds to a single product and it's identified by a unique Id. Now each product can have multiple "codes" associated with that product. For example: Id | Code ---------------------- 0001 | IN,ON,ME,OH 0002 | ON,VI,AC,ZO 0003 | QA,PS,OO,ME What I'm trying to do is create a stored procedure so that I can pass in a codes like "ON,ME" and have it return every product that contains the "ON" or "ME" code. Since the codes are comma separated, I don't know how I can split those and search them. Is this possible using only TSQL? Edit: It's a mission critical table. I don't have the authority to change it.

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• Using Multiple Databases

  - by sergiuoala

  A company is hired by another company for helping in a certain field. So I created the following tables: Companies: id, company name, company address Administrators: (in relation with companies) id, company_id, username, email, password, fullname Then, each company has some workers in it, I store data about workers. Hence, workers has a profession, Agreement Type signed and some other common things. Now, the parent tables and data in it for workers (Agreement Types, Professions, Other Common Things) are going to be the same for each company. Should I create 1 new database for each company? Or store All data into the same database? Thanks.

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• Simple question on database query.

  - by GK

  I have been asked in an interview, To write a sql query which fetches the first three records with highest value on some column from a table. i had written a query which fetched all the records with highest value, but didnt get how exactly i can get only first three records of those. could you help me in this. thanks.

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• When is BIG, big enough for a database?

  - by David ???

  I'm developing a Java application that has performance at its core. I have a list of some 40,000 "final" objects, i.e., I have an initialization input data of 40,000 vectors. This data is unchanged throughout the program's run. I am always preforming lookups against a single ID property to retrieve the proper vectors. Currently I am using a HashMap over a sub-sample of a 1,000 vectors, but I'm not sure it will scale to production. When is BIG, actually big enough for a use of DB? One more thing, an SQLite DB is a viable option as no concurrency is involved, so I guess the "threshold" for db use, is perhaps lower.

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• database design help for game / user levels / progress

  - by sprugman

  Sorry this got long and all prose-y. I'm creating my first truly gamified web app and could use some help thinking about how to structure the data. The Set-up Users need to accomplish tasks in each of several categories before they can move up a level. I've got my Users, Tasks, and Categories tables, and a UserTasks table which joins the three. ("User 3 has added Task 42 in Category 8. Now they've completed it.") That's all fine and working wonderfully. The Challenge I'm not sure of the best way to track the progress in the individual categories toward each level. The "business" rules are: You have to achieve a certain number of points in each category to move up. If you get the number of points needed in Cat 8, but still have other work to do to complete the level, any new Cat 8 points count toward your overall score, but don't "roll over" into the next level. The number of Categories is small (five currently) and unlikely to change often, but by no means absolutely fixed. The number of points needed to level-up will vary per level, probably by a formula, or perhaps a lookup table. So the challenge is to track each user's progress toward the next level in each category. I've thought of a few potential approaches: Possible Solutions Add a column to the users table for each category and reset them all to zero each time a user levels-up. Have a separate UserProgress table with a row for each category for each user and the number of points they have. (Basically a Many-to-Many version of #1.) Add a userLevel column to the UserTasks table and use that to derive their progress with some kind of SUM statement. Their current level will be a simple int in the User table. Pros & Cons (1) seems like by far the most straightforward, but it's also the least flexible. Perhaps I could use a naming convention based on the category ids to help overcome some of that. (With code like "select cats; for each cat, get the value from Users.progress_{cat.id}.") It's also the one where I lose the most data -- I won't know which points counted toward leveling up. I don't have a need in mind for that, so maybe I don't care about that. (2) seems complicated: every time I add or subtract a user or a category, I have to maintain the other table. I foresee synchronization challenges. (3) Is somewhere in between -- cleaner than #2, but less intuitive than #1. In order to find out where a user is, I'd have mildly complex SQL like: SELECT categoryId, SUM(points) from UserTasks WHERE userId={user.id} & countsTowardLevel={user.level} groupBy categoryId Hmm... that doesn't seem so bad. I think I'm talking myself into #3 here, but would love any input, advice or other ideas.

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• mysql database design: threads and replies

  - by ajsie

  in my forum i have threads and replies. one thread has multiple replies. but then, a reply can be a reply of an reply (like google wave). because of that a reply has to have a column "reply_id" so it can point to the parent reply. but then, the "top-level" replies (the replies directly under the thread) will have no parent reply. so how can i fix this? how should the columns be in the reply table (and thread table). at the moment it looks like this: threads: id title body replies: id thread_id (all replies will belong to a thread) reply_id (here lies the problem. the top-level replies wont have a parent reply) body what could a smart design look like to enable reply a reply?

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• How to map one class against multiple tables with SQLAlchemy?

  - by tote

  Lets say that I have a database structure with three tables that look like this: items - item_id - item_handle attributes - attribute_id - attribute_name item_attributes - item_attribute_id - item_id - attribute_id - attribute_value I would like to be able to do this in SQLAlchemy: item = Item('item1') item.foo = 'bar' session.add(item) session.commit() item1 = session.query(Item).filter_by(handle='item1').one() print item1.foo # => 'bar' I'm new to SQLAlchemy and I found this in the documentation (http://www.sqlalchemy.org/docs/05/mappers.html#mapping-a-class-against-multiple-tables): j = join(items, item_attributes, items.c.item_id == item_attributes.c.item_id). \ join(attributes, item_attributes.c.attribute_id == attributes.c.attribute_id) mapper(Item, j, properties={ 'item_id': [items.c.item_id, item_attributes.c.item_id], 'attribute_id': [item_attributes.c.attribute_id, attributes.c.attribute_id], }) It only adds item_id and attribute_id to Item and its not possible to add attributes to Item object. Is what I'm trying to achieve possible with SQLAlchemy? Is there a better way to structure the database to get the same behaviour of "dynamic columns"?

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• How to store opening weekdays in a database

  - by JoaoPedro

  I have a group of checkboxes where the user selects some of the weekdays (the opening days of a store). How can I save the selected days? Should I save something like 0111111 (zero means closed on sunday) on the same field and split the result when reading the data? Or create a field for each day and store 0 or 1 on each (weird)?

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• How to retrieve items from a database c#

  - by Poppy

  I have 3 tables "pics", "shows", "showpics" I want to be able to edit the table "shows". In order to do this i need to retrive the pictures that the show contains (the pictures are stored in the table "pics") the "showpics" table acts as a link does anyone have any ideas as im completely lost and have no idea where to even start Thanks

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