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• Can't create a MySQL query that generates 4 rows for each row in the table it references.

  - by UkraineTrain

  I need to create a MySQL query that generates 4 rows for each row in the table it references. I need some of the information in those rows to repeat and some to be different. In the table each row stands for one day. I need to break the day up in 6 hour increments, hence the four rows for each entry. I need to create one column which for each day will have '12AM', '6AM', '12PM', and '6PM' values and another column will have the corresponding numeric values calculated for those entries. Thanks a lot in advance and I will really appreciate any help on this.

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• Efficient update of SQLite table with many records

  - by blackrim

  I am trying to use sqlite (sqlite3) for a project to store hundreds of thousands of records (would like sqlite so users of the program don't have to run a [my]sql server). I have to update hundreds of thousands of records sometimes to enter left right values (they are hierarchical), but have found the standard update table set left_value = 4, right_value = 5 where id = 12340; to be very slow. I have tried surrounding every thousand or so with begin; .... update... update table set left_value = 4, right_value = 5 where id = 12340; update... .... commit; but again, very slow. Odd, because when I populate it with a few hundred thousand (with inserts), it finishes in seconds. I am currently trying to test the speed in python (the slowness is at the command line and python) before I move it to the C++ implementation, but right now this is way to slow and I need to find a new solution unless I am doing something wrong. Thoughts? (would take open source alternative to SQLite that is portable as well)

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• [H2 and Firebird]auto_increment, identity or trigger plus generator?

  - by blow

  Hi all, in Firebird the only way to have an auto increment coloumn is to setup a generator and use it with a trigger. In H2 db there are auto_increment and identity keywords to do it. What is the best way? Mysql use auto_increment too, but there is some problems with cuncurrence read and table lock, isn't true? Thank you.

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• What is the fastest way to get a DataTable into SQL Server?

  - by John Gietzen

  I have a DataTable in memory that I need to dump straight into a SQL Server temp table. After the data has been inserted, I transform it a little bit, and then insert a subset of those records into a permanent table. The most time consuming part of this operation is getting the data into the temp table. Now, I have to use temp tables, because more than one copy of this app is running at once, and I need a layer of isolation until the actual insert into the permanent table happens. What is the fastest way to do a bulk insert from a C# DataTable into a SQL Temp Table? I can't use any 3rd party tools for this, since I am transforming the data in memory. My current method is to create a parameterized SqlCommand: INSERT INTO #table (col1, col2, ... col200) VALUES (@col1, @col2, ... @col200) and then for each row, clear and set the parameters and execute. There has to be a more efficient way. I'm able to read and write the records on disk in a matter of seconds...

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• Fastest way to do a weighted tag search in SQL Server

  - by Hasan Khan

  My table is as follows ObjectID bigint Tag nvarchar(50) Weight float Type tinyint I want to get search for all objects that has tags 'big' or 'large' I want the objectid in order of sum of weights (so objects having both the tags will be on top) select objectid, row_number() over (order by sum(weight) desc) as rowid from tags where tag in ('big', 'large') and type=0 group by objectid the reason for row_number() is that i want paging over results. The query in its current form is very slow, takes a minute to execute over 16 million tags. What should I do to make it faster? I have a non clustered index (objectid, tag, type) Any suggestions?

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• minimal cover for functional dependencies

  - by user2975836

  I have the following problem: AB -> CD H->B G ->DA CD-> EF A -> HJ J>G I understand the first step (break down right hand side) and get the following results: AB -> C AB -> D H -> B G -> D G -> A CD -> E CD -> F A -> H A -> J J -> G I understand that A - h and h - b, therefore I can remove the B from AB - c and ab - D, to get: A -> C A -> D H -> B G -> D G -> A CD -> E CD -> F A -> H A -> J J -> G The step that follows is what I can't compute (reduce the left hand side) Any help will be greatly appreciated.

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• Solr; What does this mean?

  - by Camran

  At the end of the README.txt file which is located in the example directory under solr, I find this line: NOTE: This Solr example server references SolrCell jars outside of the server directory with statements in the solrconfig.xml. If you make a copy of this example server and wish to use the ExtractingRequestHandler (SolrCell), you will need to copy the required jars into solr/lib or update the paths to the jars in your solrconfig.xml What does this mean? Do I have to make some adjustment before uploading solr to my server? Also, if you know, what is Solr-nightly:s difference to regular solr? The tutorial states "solr-nightly.zip" but on their download section I cant find it.

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• Better alternative to autonumber primary keys

  - by Comrad_Durandal

  I am looking for a better primary key than the autonumber data type, namely for the reason that it's limited to a long integer, when I really just need the field to reflect a number or text string that will never ever repeat, no matter HOW many records are added or deleted from the table. The problem is I am not sure how to implement something like turning the current date and time into a hexadecimal string and using that as a unique field I can use as a primary key. Am I just being too paranoid about running out of space?

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• Doctrine + SQL Server Stored Procedures.

  - by Rigo Reis

  How can I call a stored procedure using Doctrine?

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• What is best tool to compare two MSSQL databases (schema and data)?

  - by tomaszs

  I would like to compare two SQL Server databases including schema (table structure) and data in tables too. What is best tool to do this?

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• 2 Select or 1 Join query ?

  - by xRobot

  I have 2 tables: book ( id, title, age ) ---- 100 milions of rows author ( id, book_id, name, born ) ---- 10 millions of rows Now, supposing I have a generic id of a book. I need to print this page: Title: mybook authors: Tom, Graham, Luis, Clarke, George So... what is the best way to do this ? 1) Simple join like this: Select book.title, author.name From book, author WHERE ( author.book_id = book.id ) AND ( book.id = 342 ) 2) For avoid the join, I could make 2 simple query: Select title FROM book WHERE id = 342 Select name FROM author WHERE book_id = 342 What is the most efficient way ?

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• In Django, how do I set a unique on a columN?

  - by alex

  class Radio(models.Model): title = models.CharField(max_length=2000, blank=True, null=True) listeners = models.IntegerField(default = 0, blank=True, null=True) I don't want duplicate TITLE column. How do I set a unique key?

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• diffing two databases

  - by flybywire

  Is there a tool to find the difference between two databases. Both the schema and the actual data are pretty much the same, but not 100%. Do you know a tool that can help to succinctly describe the changes.

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• Fastest way to store/retrieve a dictionary - SQL, text file...?

  - by AP257

  Hi all, This is a really really super dumb question, so I apologise, but I'd be grateful for some advice. I've got a text file of words and word frequencies. It's very large - theoretically we're talking millions of rows. I just want to retrieve values from the file, and do it as quickly and efficiently as possible (for a web app, in Django). My question is: what is the best way to store and retrieve the values? Should import them into SQL? Or keep the file and use grep? Or put them into a JSON dictionary...? Or some other way? Sorry for the dumb question, would be very grateful for advice!

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• Facebook style messaging system schema design

  - by Jamie

  Hi all, I'm looking to implement a facebook style messaging system (thread messages) into a site of mine. Do you think this schema markup looks okay? Doctrine schema.yml: UserMessage: tableName: user_message actAs: [Timestampable] columns: id: { type: integer(10), primary: true, autoincrement: true } sender_id : { type: integer(10), notnull: true } sender_read: { type: boolean, default: 1 } subject: { type: string(255), notnull: true } message: { type: string(1000), notnull: true } hash: { type: string(32), notnull: true } relations: UserMessageRecipient as Recipient: type: many local: id foreign: message_id UserMessageReply as Reply: type: many local: id foreign: message_id UserMessageReply: tableName: user_message_reply columns: id: { type: integer(10), primary: true, autoincrement: true } user_message_id as message_id: { type: integer(10), notnull: true } message: { type: string(1000), notnull: true } sender_id: { type: integer(10), notnull: true } relations: UserMessage as Message: local: message_id foreign: id type: one UserMessageRecipient: tableName: user_message_recipient actAs: [Timestampable] columns: id: { type: integer(10), primary: true, autoincrement: true } user_message_id as message_id: { type: integer(10), notnull: true } recipient_id: { type: integer(10), notnull: true } recipient_read: { type: boolean, default: 0 } When I a new reply is made,i'll make sure the boolean for "recipient_read" for each recipient is set to false and of course i'll make sure sender_read is set to false too. I'm using a hash for the URL: http://example.com/user/messages/aadeb18f8bdaea49882ec4d2a8a3c062 (As the id will be starting from 1, i don't wish to have http://example.com/user/messages/1. Yeah, I could start incrementing from a bigger number, but i'd prefer to start at 1.) Is this a good way to go about it? Your thoughts and suggestions would be hugely appreciated. Thanks guys!

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• How do I get a PDF link in a Word document to open in the default browser?

  - by Tweek

  I'm trying to create a Word document with links to resources on the web. If I create a hyperlink to a regular HTML file, when I click on the link, it opens in my default browser (Google Chrome) as expected. However, if I click on a link to a PDF file on a website, it opens in Internet Explorer. Before it opens, I also get the following prompt: Microsoft Office Opening http://www.example.com/example.pdf Some files can contain viruses or otherwise be harmful to your computer. It is important to be certain that this file is from a trustworthy source. Would you like to open this file? OK Cancel I'm using Office 2010, but I'm asking for a user who is using Office 2007 and is experiencing the same issue. (His default browser is Firefox.) We're both on Windows 7.

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• Django: How/Where to store a value for a session without unnecessary DB hits

  - by GerardJP

  Hi all, I have an extended userprofile with AUTH_PROFILE_MODULE (ref: http://tinyurl.com/yhracqq) I would like to set a user.is_guru() method similar to user.is_active(). This would results for al views (or rather templates) to e.g. disable/enable certain user messages, displaying of widgets, etc. The boolean is stored in the extended user profile model, but I want to avoid hitting the DB for every view. So the questions is .. Do I use a context_processor, a template tag, session_dict or what have you to, possible cached, store this info for the duration of the users visit. Note: I dont have performance issues, so it's definitely filed under premature optimization. I just want to avoid generating extra work in the future :). Any pointers are very welcome. Thanx and greetz! Gerard.

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• sql combine two subqueries

  - by Claudiu

  I have two tables. Table A has an id column. Table B has an Aid column and a type column. Example data: A: id -- 1 2 B: Aid | type ----+----- 1 | 1 1 | 1 1 | 3 1 | 1 1 | 4 1 | 5 1 | 4 2 | 2 2 | 4 2 | 3 I want to get all the IDs from table A where there is a certain amount of type 1 and type 3 actions. My query looks like this: SELECT id FROM A WHERE (SELECT COUNT(type) FROM B WHERE B.Aid = A.id AND B.type = 1) = 3 AND (SELECT COUNT(type) FROM B WHERE B.Aid = A.id AND B.type = 3) = 1 so on the data above, just the id 1 should be returned. Can I combine the 2 subqueries somehow?

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• how to get transform a local image to a web accessable image

  - by hguser

  Hi: Generally,if we want to display a image in the web page,we give the uri of the image resource like: http://host:port/image/xxx.jpg. Now,there are some images in my file system,and I save its absolute path in the db. Like this; id name address image 1 xxxx xxxx C:/images/xxx.jpg Now if the entity is retrived,its image should be displayed in the page. How to make it? What I thought is copy the image under the web server dir,then build its url,then the page can render it. But I wonder if this is a good idea? Is there any other way?

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• How to use Externel Triggers on Oracle 11g..

  - by RBA

  Hi, I want to fire a trigger whenever an insert command is fired.. The trigger will access a pl/sql file which can change anytime.. So the query is, if we design the trigger, how can we make sure this dynamic thing happens.. As during the stored procedure, it is not workingg.. I think - it should work for 1) External Procedures 2) Execute Statement Please correct me, if I am wrong.. I was working on External Procedures but i am not able to find the way to execute the external procedure from here on.. SQL> CREATE OR REPLACE FUNCTION Plstojavafac_func (N NUMBER) RETURN NUMBER AS 2 LANGUAGE JAVA 3 NAME 'Factorial.J_calcFactorial(int) return int'; 4 / @@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@ SQL> CREATE OR REPLACE TRIGGER student_after_insert 2 AFTER INSERT 3 ON student 4 FOR EACH ROW How to call the procedure from heree... And does my interpretations are right,, plz suggest.. Thanks.

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• RSS feed publish date-time(GMT) to unix timestamp format using php

  - by PHP-Prabhu

  can anyone reply me, How do convert RSS feed publish date-time(GMT) to UNIX time-stamp using php. I need to store the date into my table with the field'd data type as TIMESTAMP.

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• application specific seed data population

  - by user339108

  Env: JBoss, (h2, MySQl, postgres), JPA, Hibernate 3.3.x @Id @GeneratedValue(strategy = IDENTITY) private Integer key; Currently our primary keys are created using the above annotation. We expect to support a large number of users (~million users), what key should be used. Should it be Integer or Long or should I use the unsigned versions of the above declarations. We have a j2ee application which needs to be populated with some seed data on installation. On purchase, the customer creates his own data on top of the application. We just want to make sure that there is enough room to ship, modify or add data for future releases. What would be the best mechanism to support this, we had looked at starting all table identifiers from a certain id (say 1000) but this mandates modifying primary key generation to have table or sequence based generators and we have around ~100 tables. We are not sure if this is the right strategy for this. If we use a signed integer approach for the key, would it make sense to have the seed data as everything starting from 0 and below (i.e -ve numbers), so that all customer specific data will be available on 0 and above (i.e. +ve numbers)

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• MySQL query returning mysql_error

  - by Sebastian

  This returns mysql_error: <?php $name = $_POST['inputName2']; $email = $_POST['inputEmail2']; $instruments = $_POST['instruments']; $city = $_POST['inputCity']; $country = $_POST['inputCountry']; $distance = $_POST['distance']; // ^^ These all echo properly ^^ // CONNECT TO DB $dbhost = "xxx"; $dbname = "xxx"; $dbuser = "xxx"; $dbpass = "xxx"; $con = mysqli_connect("$dbhost", "$dbuser", "$dbpass", "$dbname"); if (mysqli_connect_errno()) { echo "Failed to connect to MySQL: " . mysqli_connect_error(); } $query = "INSERT INTO depfinder (name, email, instrument1, instrument2, instrument3, instrument4, instrument5, city, country, max_distance) VALUES ($name, $email, $instruments[0], $instruments[1], $instruments[2], $instruments[3], $instruments[4], $city, $country, $max_distance)"; $result = mysqli_query($con, $query) or die(mysqli_error($con)); // script fails here if (!$result) { echo "There was a problem with the signup process. Please try again later."; } else { echo "Success"; } } ?> N.B. I'm not sure whether it's relevant, but the user may not choose five instruments so some $instrument[] array values may be empty. Bonus question: is my script secure enough or is there more I could do?

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• Help me write a nicer SQL query in Rails

  - by Sainath Mallidi

  Hi, I am trying to write an SQL query to update some of the attributes that are regularly pulled from source. the output will be a text file with the following fields: author, title, date, popularity I have two tables to update one is the author information and the other is popularity table. And the Author Active Record object has one popularity. Currently I'm doing it like this.\ arr.each { |x| x = x.split(" ") results = Author.find_by_sql("SELECT authors.id FROM authors, priorities WHERE authors.id=popularity.authors_id AND authors.author = x[0]") results[0].popularity.update_attribute("popularity", x[3]) I need two tables because the popularity keeps changing, and I need only the top 1000 popular ones, but I still need to keep the previously popular ones also. Is there any nicer way to do this, instead of one query for every new object. Thanks.

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• Data Warehouse: Modelling a future schedule

  - by Pat

  I'm creating a DW that will contain data on financial securities such as bonds and loans. These securities are associated with payment schedules. For example, a bond could pay quarterly, while a mortage would usually pay monthly (sometimes biweekly). The payment schedule is created when the security is traded and, in the majority of cases, will remain unchanged. However, the design would need to accomodate those cases where it does change. I'm currently attempting to model this data and I'm having difficulty coming up with a workable design. One of the most commonly queried fields is "next payment date". Users often want to know when a security will pay next. Therefore, I want to make it as easy as possible for them to get the next payment date and amount for each security. Also, users often run historical queries in which case they'd want the next payment date and amount as of a specific point in time. For example, they may want to look back at 1/31/09 and query the next payment dates (which would usually be in February 2009 for mortgages). It's also common that they want to query a security's entire payment schedule, which might consist of 360 records (30 year mortgage x 12 payments/year). Since the next payment date and amount would be changing each month or even biweekly, these fields wouldn't seem to fit into a slow-changing dimension very well. It would probably make more sense to use a fact table, but I'm unsure of how to model it. Any ideas would be greatly appreciated.

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