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Search found 1908 results on 77 pages for 'relational operators'.

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• Microsoft SQL Server 2005 - using the modulo operator

  - by cc0

  So I have a silly problem, I have not used much SQL Server before, or any SQL for that matter. I basically have a minor mathematical problem that I need solved, and I thought modulo would be good. I have a number of dates in the database, but I need them be rounded off to the closest [dynamic integer] (could be anything from 0 to 5000000) which will be input as a parameter each time this query is called. So I thought I'd use modulo to find the remainder, then subtract that remainder from the date. If there is a better way, or an integrated function, please let me know! What would be the syntax for that? I've tried a lot of things, but I keep getting error messages like integers/floats/decimals can't be used with the modulo operators. I tried casting to all kinds of numeric datatypes. Any help would be appreciated.

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• R equivalent of .first or .last sas operator

  - by Giorgio Spedicato

  Does anybody know what is the best R alternative to SAS first. or last. operators? I did find none. SAS has the FIRST. and LAST. automatic variables, which identify the first and last record amongst a group with the same value with a particular variable; so in the following dataset FIRST.model and LAST.model are defined: Model,SaleID,First.Model,Last.Model Explorer,1,1,0 Explorer,2,0,0 Explorer,3,0,0 Explorer,4,0,1 Civic,5,1,0 Civic,6,0,0 Civic,7,0,1

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• Table and Column names causing problems

  - by craig

  I have an issue when the T4 linq templates generate the classes for my MySql db using subsonic 3. It looks like one of our table names "operator" is causing problems in the Context.cs generated class. In the following line of code in Context.cs Visual Studio sees <operator> as a c# operator and generates a compilation error of "Type expected" public Query<operator> operators { get; set; } Is there anyway I can work around this without having to rename my database table and column names? For example hard coding something in Settings.ttinclude to use or map different names to specific db tables and columns?

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• When to use CouchDB vs RDBMS

  - by Andrew Whitehouse

  I am looking at CouchDB, which has a number of appealing features over relational databases including: intuitive REST/HTTP interface easy replication data stored as documents, rather than normalised tables I appreciate that this is not a mature product so should be adopted with caution, but am wondering whether it is actually a viable replacement for an RDBMS (in spite of the intro page saying otherwise - http://couchdb.apache.org/docs/intro.html). Under what circumstances would CouchDB be a better choice of database than an RDBMS (e.g. MySQL), e.g. in terms of scalability, design + development time, reliability and maintenance. Are there still cases where an RDBMS is still clearly the right choice? Is this an either-or choice, or is a hybrid solution more likely to emerge as best practice?

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• BigInteger or not BigInteger?

  - by Alon

  In Java, most of the primitive types are signed (one bit is used to represent the +/-), and therefore when I am exceed the limits of this type, I can get many strange things, like negative numbers. In the BigInteger class, I have no limits and there are some helpful functions there but it is pretty depressing to convert your beautiful code to work with the BigInteger class, specially when primitive operators don't work there and you must use functions from this class. I was wondering if you had this problem, and if you have any better solution than the BigInteger class? Thank you.

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• MySQL Stored Procedure: Boolean Logic in IF THEN

  - by xncroft

  I'm looking for the proper syntax (if this is possible in MySQL stored procedures) for using logical operators in an IF THEN statement. Here's something along the lines of what I would like to do, but I'm not certain if I should type "OR" or "||" in the IF ... THEN clause: DELIMITER $$ CREATE PROCEDURE `MyStoredProc` (_id INT) BEGIN DECLARE testVal1 INT DEFAULT 0; DECLARE testVal2 INT DEFAULT 0; SELECT value1, value2 INTO testVal1, testVal2 FROM ValueTable WHERE id = _id; IF testVal1 > 0 OR testVal2 > 0 THEN UPDATE ValueTable SET value1 = (value1+1) WHERE id=_id; END IF; END$$

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• large amount of data in many text files - how to process?

  - by Stephen

  Hi, I have large amounts of data (a few terabytes) and accumulating... They are contained in many tab-delimited flat text files (each about 30MB). Most of the task involves reading the data and aggregating (summing/averaging + additional transformations) over observations/rows based on a series of predicate statements, and then saving the output as text, HDF5, or SQLite files, etc. I normally use R for such tasks but I fear this may be a bit large. Some candidate solutions are to 1) write the whole thing in C (or Fortran) 2) import the files (tables) into a relational database directly and then pull off chunks in R or Python (some of the transformations are not amenable for pure SQL solutions) 3) write the whole thing in Python Would (3) be a bad idea? I know you can wrap C routines in Python but in this case since there isn't anything computationally prohibitive (e.g., optimization routines that require many iterative calculations), I think I/O may be as much of a bottleneck as the computation itself. Do you have any recommendations on further considerations or suggestions? Thanks

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• Video learning for database design

  - by donpal

  I'm trying to learn good relational database design (using mysql and php if that makes any difference). I've already done some database work, so I'm not totally clueless, but I suspect that my solutions may not have adhered to best practices for efficient searching, optimization, etc. Can someone suggest a good set of videos on the topic? If you know something is superb or has really made a difference in your own learning, please post your suggestion. Prefer videos, but books (as long as they're not too huge) are ok too. But prefer videos. Thank you

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• how to work with strings and integers as bit strings in python?

  - by Manuel

  Hello! I'm developing a Genetic Algorithm in python were chromosomes are composed of strings and integers. To apply the genetic operations, I want to convert these groups of integers and strings into bit strings. For example, if one chromosome is: ["Hello", 4, "anotherString"] I'd like it to become something like: 0100100100101001010011110011 (this is not actual translation). So... How can I do this? Chromosomes will contain the same amount of strings and integers, but this numbers can vary from one algorithm run to another. To be clear, what I want to obtain is the bit representation of each element in the chromosome concatenated. If you think this would not be the best way to apply genetic operators (such as mutation and simple crossover) just tell me! I'm open to new ideas. Thanks a lot! Manuel

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• Is it possible to create a new T-SQL Operator using CLR Code in SQL Server?

  - by Eoin Campbell

  I have a very simple CLR Function for doing Regex Matching public static SqlBoolean RegExMatch(SqlString input, SqlString pattern) { if (input.IsNull || pattern.IsNull) return SqlBoolean.False; return Regex.IsMatch(input.Value, pattern.Value, RegexOptions.IgnoreCase); } It allows me to write a SQL Statement Like. SELECT * FROM dbo.table1 WHERE dbo.RegexMatch(column1, '[0-9][A-Z]') = 1 -- match entries in col1 like 1A, 2B etc... I'm just thinking it would be nice to reformulate that query so it could be called like SELECT * FROM dbo.table1 WHERE column1 REGEXLIKE '[0-9][A-Z]' Is it possible to create new comparison operators using CLR Code. (I'm guessing from my brief glance around the web that the answer is NO, but no harm asking)

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• MySQL and Collation

  - by user294787

  I have a table with a column using utf8_unicode_ci character set. This table stores Japanese data and my problem is that using this character set, I'm not able to store the same word written in katakana and hiragana because it's considered to be the same word. For example ??? and ???, which mean I, me. I know that I can change the character set to utf8_general_ci to resolve this problem but is it possible to bypass this limitation ? I mean, keep utf8_unicode_ci character set and make those two words be inserted? Is it possible to make this work using CONVERT or CAST operators? Thanks.

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• Is adding indexes to a SQL Server ever a bad idea?

  - by Aerik

  We have a mid-size SQL Server based application that has no indexes defined. Not even on the the identity columns. I suggested to our moderately expensive application consultant that perhaps we might get better performance (particularly as our database grows) by creating some indexes on appropriate fields, and he said: "Indexes will significantly impact other areas of the application and customers should not create them under any circumstances." Anybody ever heard of anything like this? Are there ever circumstances where one should not create any indexes? I can see nothing special about this app - it's got int identity columns, then lots of string columns, bunch of relational tables but nothing special or weird that I can see. Thanks!

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• How do Scala parser combinators compare to Haskell's Parsec?

  - by artif

  I have read that Haskell parser combinators (in Parsec) can parse context sensitive grammars. Is this also true for Scala parser combinators? If so, is this what the "into" (aka "") function is for? What are some strengths/weaknesses of Scala's implementation of parser combinators, vs Haskell's? Do they accept the same class of grammars? Is it easier to generate error messages or do other miscellaneous useful things with one or the other? How does packrat parsing (introduced in Scala 2.8) fit into this picture? Is there a webpage or some other resource that shows how different operators/functions/DSL-sugar from one language's implementation maps onto the other's?

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• Scaffolding Web Services in Grails

  - by Dan

  I need to implement a web app, but instead of using relational database I need to use different SOAP Web Services as a back-end. An important part of application only calls web services and displays the result. Since Web Services are clearly defined in form of Operation: In parameters and Return Type it seems to me that basic GUI could be easily constructed just like in the case of scaffolding based on Domain Entities. For example in case of SearchProducts web service operation I need to enter search parameters as input, so the search page can be constructed. Operation will return a list of products, so I need a page that will display this list in some kind of table. Is there already some library in grails that let you achieve this. If not, how would you go about creating one?

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• Cloned Cached item has memory issues

  - by ioWint

  Hi there, we are having values stored in Cache-Enterprise library Caching Block. The accessors of the cached item, which is a List, modify the values. We didnt want the Cached Items to get affected. Hence first we returned a new List(IEnumerator of the CachedItem) This made sure accessors adding and removing items had little effect on the original Cached item. But we found, all the instances of the List we returned to accessors were ALIVE! Object relational Graph showed a relationship between this list and the EnterpriseLibrary.CacheItem. So we changed the return to be a newly cloned List. For this we used a LINQ say (from item in Data select new DataClass(item) ).ToList() even when you do as above, the ORG shows there is a relationship between this list and the CacheItem. Cant we do anything to create a CLONE of the List item which is present in the Enterprise library cache, which DOESNT have ANY relationship with CACHE?!

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• Core Data vs SQLite 3

  - by Jason Medeiros

  I am already quite familiar with relational databases and have used SQLite (and other databases) in the past. However, Core Data has a certain allure, so I am considering spending some time to learn it for use in my next application. Is there much benefit to using Core Data over SQLite, or vice versa? What are the pros/cons of each? I find it hard to justify the cost of learning Core Data when Apple doesn't use it for many of its flagship applications like Mail.app or iPhoto.app - instead opting for SQLite databases. SQLite is also used extensively on the iPhone. Can those familiar with using both comment on their experience? Perhaps, as with most things, the question is deeper than just using one over the other?

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• Essential skills of a Data Scientist

  - by harshsinghal

  I would like to know more about the relevant skills in the arsenal of a Data Scientist, and with new technologies coming in every day, how one picks and chooses the essentials. A few ideas germane to this discussion: Knowing SQL and the use of a DB such as MySQL, PostgreSQL was great till the advent of NoSql and non-relational databases. MongoDB, CouchDB etc. are becoming popular to work with web-scale data. Knowing a stats tool like R is enough for analysis, but to create applications one may need to add Java, Python, and such others to the list. Data now comes in the form of text, urls, multi-media to name a few, and there are different paradigms associated with their manipulation. What about cluster computing, parallel computing, the cloud, Amazon EC2, Hadoop ? OLS Regression now has Artificial Neural Networks, Random Forests and other relatively exotic machine learning/data mining algos. for company Thoughts?

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• Is there a declarative language for data definitions?

  - by Jekke

  Reading about WPF and thinking about my application's data store at the same time led me to wonder if there are any languages or tools that allow you to define relational data in a declarative way? A shallow Google search suggests no such thing exists. Yet it seems so obviously useful. The kind of tool I have in mind would declaratively describe (at least) entities, relationships and views is a platform-agnostic way that would act as an abstraction layer between data-driven applications and their datastores. Does any such tool exist?

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• Is it possible to create a new T-SQL Operator using CLR Code in MSSQL?

  - by Eoin Campbell

  I have a very simple CLR Function for doing Regex Matching public static SqlBoolean RegExMatch(SqlString input, SqlString pattern) { if (input.IsNull || pattern.IsNull) return SqlBoolean.False; return Regex.IsMatch(input.Value, pattern.Value, RegexOptions.IgnoreCase); } It allows me to write a SQL Statement Like. SELECT * FROM dbo.table1 WHERE dbo.RegexMatch(column1, '[0-9][A-Z]') = 1 -- match entries in col1 like 1A, 2B etc... I'm just thinking it would be nice to reformulate that query so it could be called like SELECT * FROM dbo.table1 WHERE column1 REGEXLIKE '[0-9][A-Z]' Is it possible to create new comparison operators using CLR Code. (I'm guessing from my brief glance around the web that the answer is NO, but no harm asking) Thanks, Eoin C

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• Using bash shell from within PHP

  - by Dan

  Hi everyone, In my terminal window (using Max OS X) my shell is bash. However when I run a command in PHP via shell_exec or backtick operators I see that PHP is using the Bourne Shell (sh). Here's an example of what I'm seeing: From within my terminal window: $ echo $0 - bash Also if I call php as follows: $ php -r "echo shell_exec('echo $0');" -bash However, if I create a script called test.php with the following: <?php echo shell_exec('echo $0'); ?> And then run test php I get the following: $ php test.php sh I'm wanting to use the bash shell when calling shell_exec - why is it choosing the Bourne shell and can I force it to use bash? Thanks! Dan

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• Fetching all uploaded,tagged in and share videos in Facebook by FQL

  - by himanshu

  In my app, i want to fetch all videos of logged in user i.e. videos that are uploaded by user, videos share by user, user tagged in etc. Currently im using "stream" query as: SELECT created_time, post_id, actor_id, type, updated_time, attachment FROM stream WHERE created_time>1075593600 AND type IN (56, 80, 128, 237, 272) AND source_id=me() limit 10000 As you can see i use "type IN" to fetch required videos but this query is not fetching all videos of mine . I have two videos in 2011 one of which is uploaded and other one is shared.But i m not getting these two. Also in developer.facebook it was written that "Each query of the stream table is limited to the previous 30 days or 50 posts, whichever is greater, however you can use time-specific fields such as created_time along with FQL operators (such as < or ) to retrieve a much greater range of posts." So i tried "created time0" i.e.(1970) and other like timestamp of 2001 but still i m not getting all. Please help..its urgent.Thanks

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• Ruby RegEx not matching valid expression

  - by Matthew Carriere

  I have the following expression: ^\w(\s(+|-|\/|*)\s\w)*$ This simply looks to match a mathematical expression, where a user is prompted for terms separated by basic operators (ex: price + tax) The user may enter more than just 2 terms and one operator (ex: price + tax + moretax) I tested this expression in Rubular http://rubular.com/ With the terms: a + a (MATCH) a + a + a (MATCH) a + a + a + a a a + a a Everything works, but when I use it in Ruby it does not work! expression =~ /^\w(\s(+|-|\/|*)\s\w)*$/ I started picking the expression apart and noticed that if I remove the start of line caret it finds matches but isn't correct. a + a (MATCH) a a (MATCH) <-- this is not correct Why is this expression not working in Ruby code? (I am using Ruby 1.8.7 p174)

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• Are there any small scale, durable document/object databases?

  - by Joe Doyle

  I have a few .Net projects that would benefit from using a document/object database opposed to a relational one. I think that db4o would be a good choice, but we're not sure how much the cost is. I'd love to use MongoDB but it's design isn't for small scale, single server applications. Are there other options out there that I just haven't run across for small scale applications? EDIT: So is this a space that doesn't have a good solution, yet? Are there no small scale & durable document databases? Would my best choice be to use MongoDB and set the --syncdelay option set to 1?

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• Code golf: Reverse Polish notation (postfix) evaluator

  - by Dario

  After having had code-golf contests on ordinary mathematical expressions, I just thought it would also be quite interesting how short an evaluation function for postfix notation (RPN) can be. Examples for RPN: 1 2 + == 3 1 2 + 3 * == 9 0 1 2 3 + + - 2 6 * + 3 / 1 - == 1 3 2 / 2.0 + == 3.5 To make things shorter, only +, -, * and /, all just in their binary version, must be supported. Operators/Operands are delimited by one space, divsions by zero don't have to be handled. The resulting code should be a function that takes the postfix string as input and returns the resulting number.

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• Conditional Join - join 1 tables 2 ways

  - by Jon H

  I have a set of (not very well normalised or relational) tables named PLAN, GROUP, PRODUCT CLIENT Most have linkage i.e. PLAN - CLIENT on clno GROUP to PRODUCT on PRODCD However, the linkage between PLAN and GROUP is tricky. A plan has 2 field of interest GRPNO and PRODCD. What I want to do is if GRPNO != 0 then join GROUP on GRPNO. However if GRPNO = 0 then I want to join GROUP on PRODCD. The frustrating thing is that the fileds I want to return in my queries are the same across the board I just need to be able to vary the join, or join the same table twice. The best I can come up with is 2 queries and merge them using datasets, or possibly using a union. Is there a nifty way to do this in one select? I should point out I am access Foxpro over ODBC to do this. Thank you!

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