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  • Asp.net mvc small amount data storage

    - by Trimack
    Hi there, I am writing some learning tests (i.e. what's the answer for...; choose correct options...). Now my question is, how should I store them. SQL db seems quite an overkill, but I really don't know what would be the best choice if I wanted to select random subset of questions etc. Perhaps some simple xml files? Thanks for advice.

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  • Natural vs surrogate keys on support tables

    - by Bugeo
    I have read many articles about the battle between natural versus surrogate primary keys. I agree in the use of surrogate keys to identify records of tables whose contents are created by the user. But in the case of supporting tables what should I use? For example, in a hypothetical table "orderStates". If you use a natural key would have the following data: TABLE ORDERSTATES {ID: "NEW", NAME: "New"} {ID: "MANAGEMENT" NAME: "Management"} {ID: "SHIPPED" NAME: "Shipped"} If I use a surrogate key would have the following data: TABLE ORDERSTATES {ID: 1 CODE: "NEW", NAME: "New"} {ID: 2 CODE: "MANAGEMENT" NAME: "Management"} {ID: 3 CODE: "SHIPPED" NAME: "Shipped"} Now let's take an example: a user enters a new order. In the case in which use natural keys, in the code I can write this: newOrder.StateOrderId = "NEW"; With the surrogate keys instead every time I have an additional step. stateOrderId_NEW = .... I retrieve the id corresponding to the recod code "NEW" newOrder.StateOrderId = stateOrderId_NEW; The same will happen every time I have to move the order in a new status. So, in this case, what are the reason to chose one key type vs the other one?

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  • Using Entity Framework, how do I specify a sort on a navagation property?

    - by Jared
    I have two tables: [Category], [Item]. They are connected by a join table: [CategoryAndItem]. It has two primary key fields: [CategoryKey], [ItemKey]. Foreign keys exist appropriately and Entity has no problem pulling this in and creating the correct navigation properties that connect the entity objects. Basically each category can have multiple items, and items can be in multiple categories. The problem is that the order of items is specified per category, so that a particular item might be third in one category but fifth in another. In the past, I have added a [Sequence] field to the join table and modified the stored procedure to handle it. But since Entity is replacing my stored procedures, I need to figure out how to make Entity handle the sequence. Any suggestions?

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  • What's wrong with this SQL query?

    - by ThinkingInBits
    I have two tables: photographs, and photograph_tags. Photograph_tags contains a column called photograph_id (id in photographs). You can have many tags for one photograph. I have a photograph row related to three tags: boy, stream, and water. However, running the following query returns 0 rows SELECT p.* FROM photographs p, photograph_tags c WHERE c.photograph_id = p.id AND (c.value IN ('dog', 'water', 'stream')) GROUP BY p.id HAVING COUNT( p.id )=3 Is something wrong with this query?

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  • Transaction Isolation on select, insert, delete

    - by Bradford
    What could possibly go wrong with the following transaction if executed by concurrent users in the default isolation level of READ COMMITTED? BEGIN TRANSACTION SELECT * FROM t WHERE pid = 10 and r between 40 and 60 -- ... this returns tid = 1, 3, 5 -- ... process returned data ... DELETE FROM t WHERE tid in (1, 3, 5) INSERT INTO t (tid, pid, r) VALUES (77, 10, 35) INSERT INTO t (tid, pid, r) VALUES (78, 10, 37) INSERT INTO t (tid, pid, r) VALUES (79, 11, 39) COMMIT

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  • Java MySQL Query Problem MySQLSyntaxErrorException When Creating a Table

    - by Aqib Mushtaq
    I fairly new to MySQL with Java, but I have executed a few successful INSERT queries however cannot seem to get the CREATE TABLE query to execute without getting the 'MySQLSyntaxErrorException' exception. My code is as follows: import java.sql.*; Statement stmt; Class.forName("com.mysql.jdbc.Driver"); String url = "jdbc:mysql://localhost:3306/mysql"; Connection con = DriverManager.getConnection(url, "root", "password"); stmt = con.createStatement(); String tblSQL = "CREATE TABLE IF NOT EXISTS \'dev\'.\'testTable\' (\n" + " \'id\' int(11) NOT NULL AUTO_INCREMENT,\n" + " \'date\' smallint(6) NOT NULL\n" + ") ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;"; stmt.executeUpdate(tblSQL); stmt.close(); con.close(); And the error is as follows: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''dev'.'testTable' ( 'id' int(11) NOT NULL AUTO_INCREMENT, 'date' smallint(6) N' at line 1 I would appreciate it if anyone could spot the mistake in this query, as I've tried executing this within phpMyAdmin and it works as it should. Thanks in advance.

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  • What is a good DBMS for archiving?

    - by Thomas.Winsnes
    I've been stuck in a MsSql/MySql world now for a few years, and I've decided to spread my wings a little further. At the moment I'm researching which DBMS is good at things needed when archiving data. Eg. lots of writes and low reads. I've seen the NoSQL crusade, but I have a very RDBMS mindset, so I'm a bit skeptical. Anyone have any suggestions? Or even any pointers to where there are some benchmarks etc for this kind of stuff. Thank you :) Thomas

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  • Passing BLOB/CLOB as parameter to PL/SQL function

    - by Ula Krukar
    I have this procedure i my package: PROCEDURE pr_export_blob( p_name IN VARCHAR2, p_blob IN BLOB, p_part_size IN NUMBER); I would like for parameter p_blob to be either BLOB or CLOB. When I call this procedure with BLOB parameter, everything is fine. When I call it with CLOB parameter, I get compilation error: PLS-00306: wrong number or types of arguments in call to 'pr_export_blob' Is there a way to write a procedure, that can take either of those types as parameter? Some kind of a superclass maybe?

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  • How Implement a system to determine if a milestone has been reached

    - by Luc M
    I have a table named stats player_id team_id match_date goal assist` 1 8 2010-01-01 1 1 1 8 2010-01-01 2 0 1 9 2010-01-01 0 5 ... I would like to know when a player reach a milestone (eg 100 goals, 100 assists, 500 goals...) I would like to know also when a team reach a milestone. I want to know which player or team reach 100 goals first, second, third... I thought to use triggers with tables to accumulate the totals. Table player_accumulator (and team_accumulator) table would be player_id total_goals total_assists 1 3 6 team_id total_goals total_assists 8 3 1 9 0 5 Each time a row is inserted in stats table, a trigger will insert/update player_accumulator and team_accumulator tables. This trigger could also verify if player or team has reached a milestone in milestone table containing numbers milestone 100 500 1000 ... A table player_milestone would contains milestone reached by player: player_id stat milestone date 1 goal 100 2013-04-02 1 assist 100 2012-11-19 There is a better way to implements a "milestone" ? There is an easiest way without triggers ? I'm using PostgreSQL

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  • MySQL Query order by numer of rows?

    - by Clemens
    hi, i have a mysql table for votes. there's am id, a project_id and a vote field (which is 1 if a specific project is voted). now i want to generate a ranking from those entries. is there a way to get the number of votes for each project_id and automatically sort the entries by the number of TRUE votes of a project with a single mysql query? Or do you know a php way? e.g. ID - Project ID - Vote 1 - 2 - 1 2 - 2 - 1 3 - 1 - 1 == Project Nr. 2 has 2 Votes Project Nr. 1 has 1 Vote Thanks in advance!

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  • SQL SERVER - Detecting non-indexed columns but used in WHERE clause

    - by Vadi
    How to detect a column included in WHERE clause but used in indexed? Little Background: Until the time the table has few number of records things will be okay, once it started having millions of records then index should be created for a column which is used in WHERE clauses in stored procs, inline queries etc., Since we have hundreds of stored procs and queries that often gets changed by the devs I wanted to have a automated way of identifying those columns that are used in WHERE clauses but not an index is created. How to do that in SQL SERVER 2008?

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  • what is the question for the query?

    - by Kevinniceguy
    Sorry...I mean what question will be for this query? SELECT SUM(price) FROM Room r, Hotel h WHERE r.hotelNo = h.hotelNo and hotelName = 'Paris Hilton' and roomNo NOT IN (SELECT roomNo FROM Booking b, Hotel h WHERE (dateFrom <= CURRENT_DATE AND dateTo >= CURRENT_DATE) AND b.hotelNo = h.hotelNo AND hotelName = 'Paris Hilton');

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  • Problem with mysql query to replace a string

    - by alex
    I've used mysql's update replace function before, but even though I think I'm following the same syntax, I can't get this to work. Here's what I'm trying to do: UPDATE contained_widgets SET preference_values = REPLACE(preference_values, '<li><a_href="/enewsletter"><span class="not-tc">eNewsletter</span></a></li>', '<li><a_href="/enewsletter"><span class="not-tc">eNewsletter</span></a></li> <li> <a_href="/projects"><span class="not-tc">Projects</span></a></li>'); Query OK, 0 rows affected (0.00 sec) Rows matched: 77 Changed: 0 Warnings: 0 I don't see what I'm missing. Any help is appreciated. I edited "a " to "a_" because the site thinks I'm posting spam links otherwise.

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  • Are there any examples/tutorials of using Spring 3.0 with Cassandra as a backend?

    - by zeroDivisible
    Hello, As I had written in title, I am trying to learn Spring 3.0 (I already know Django, Pylons and few simpler MVC frameworks) and try to use Cassandra as a backend for my web application. Are there any real world examples of doing this? Or maybe some tutorials? I know about the existence of documentation of both technologies, yet I am looking for something "faster" to read and get me rolling.

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  • Version of SQLite used in Android?

    - by Eno
    Reason: Im wondering how to handle schema migrations. The newer SQLite versions support an "ALTER TABLE" SQL command which would save me having to copy data, drop the table, recreate table and re-insert data.

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  • Is copying /var/lib/mysql a good alterntive to mysqldump?

    - by kemp
    Since I'm making a full backup of my entire debian system, I was thinking if having a copy of /var/lib/mysql directory is a viable alternative to dumping tables with mysqldump. are all informations needed contained in that directory? can single tables be imported in another mysql? can there be problems while restoring those files on a (probably slightly) different mysql server version?

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  • Does Ruby on Rails "has_many" array provide data on a "need to know" basis?

    - by Jian Lin
    On Ruby on Rails, say, if the Actor model object is Tom Hanks, and the "has_many" fans is 20,000 Fan objects, then actor.fans gives an Array with 20,000 elements. Probably, the elements are not pre-populated with values? Otherwise, getting each Actor object from the DB can be extremely time consuming. So it is on a "need to know" basis? So does it pull data when I access actor.fans[500], and pull data when I access actor.fans[0]? If it jumps from each record to record, then it won't be able to optimize performance by doing sequential read, which can be faster on the hard disk because those records could be in the nearby sector / platter layer -- for example, if the program touches 2 random elements, then it will be faster just to read those 2 records, but what if it touches all elements in random order, then it may be faster just to read all records in a sequential way, and then process the random elements. But how will RoR know whether I am doing only a few random elements or all elements in random?

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  • Multi-variable indexes in postgres

    - by Jackson Davis
    Im looking at an application where I will be doing quite a few SELECTs where I am trying to find column_a = x AND column_b = y. Is the correct to create that index that something like the following? CREATE INDEX index_name ON table (column_a, column_b)

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