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• Selecting data effectively sql

  - by learner135

  Hi, I have a very large table with over 1000 records and 200 columns. When I try to retreive records matching some criteria in the WHERE clause using SELECT statement it takes a lot of time. But most of the time I just want to select a single record that matches the criteria in the WHERE clause rather than all the records. I guess there should be a way to select just a single record and exit which would minimize the retrieval time. I tried ROWNUM=1 in the WHERE clause but it didn't really work cause I guess the engine still checks all the records even after finding the first record matching the WHERE criteria. Is there a way to optimize in case if I want to select just a few records? Thanks in advance. Edit: I am using oracle 10g.

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• Automatically Add a Prefix to Column Names for @Embeddable Classes

  - by VeeArr

  I am developing a project in which I am persisting some POJOs by adding Hibernate annotations. One problem I am running into is that code like this fails, as Hibernate tries to map the sub-fields within the Time_T onto the same column (i.e. startTime.sec and stopTime.sec both try to map to the colum sec, causing an error). @Entity public class ExampleClass { @Id long eventId; Time_T startTime; Time_T stopTime; } @Embeddable public class Time_T { int sec; int nsec; } As there will be many occurrences like this throughout the system, it would be nice if there was an option to automatically append a prefix to the column name (e.g. make the columns be startTime_sec, startTime_nsec, stopTime_sec, stopTime_nsec), without having to apply overrides on a per-field basis. Does Hibernate have this capability, or is there any other reasonable work-around?

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• how do I integrate the aspnet_users table (asp.net membership) into my existing database

  - by ooo

  i have a database that already has a users table COLUMNS: userID - int loginName - string First - string Last - string i just installed the asp.net membership table. Right now all of my tables are joined into my users table foreign keyed into the "userId" field How do i integrate asp.net_users table into my schema? here are the ideas i thought of: Add a membership_id field to my users table and on new inserts, include that new field in my users table. This seems like the cleanest way as i dont need to break any existing relationships. break all existing relationship and move all of the fields in my user table into the asp.net_users table. This seems like a pain but ultimately will lead to the most simple, normalized solution any thoughts?

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• read contents of a sql table into a data grid view

  - by syedsaleemss

  Im using c# .net windows application form. i have created a database named "resources" in SQL server 2005. In that i have a table named "resourcetable" which has two columns. now i need to read the data in the table into a datagridview. I can do this by using the connection string and querry by giving the table name. But my problem is i have a button and if i click on that button, an open dialog box should open and i should be able to select a database amomng many databases and in that selected database i have to select one table amomg many tables. i.e select a table ofa particular database. and the contents of that table are to be displayed in a datagridview.

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• Doctrine: Mixing YAML markup and db manager (navicat) editing?

  - by ropstah

  I think the answer to this question should be: No. However I hope to be corrected. I'd like to edit our database using a mixture of YAML markup + Doctrine createTables() and Navicat editing. Can I maintain the inheritance which is marked up? Example (4 steps, at step 4, Doctrine is in no way able to re-create the inheritance schema... or is it?): Step 1: Create YAML with inheritance --- Entity: columns: username: string(20) password: string(16) created_at: timestamp updated_at: timestamp User: inheritance: extends: Entity type: column_aggregation keyField: type keyValue: 1 Group: inheritance: extends: Entity type: column_aggregation keyField: type keyValue: 2 Step 2: Create tables using Doctrine (and drop/create db if nessecary) Created sql: CREATE TABLE entity (id BIGINT AUTO_INCREMENT, username VARCHAR(20), password VARCHAR(16), created_at DATETIME, updated_at DATETIME, type VARCHAR(255), PRIMARY KEY(id)) ENGINE = INNODB Step 3: Edit table using Navicat Step 4: Refresh YAML file because of 'external' edits...

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• Java. Writing a matrix in a file using column information. ( matrix transposition )

  - by Dmitry

  Hello, everybody! I have a file in which a matrix is stored. This file has a RandomAccessFile type. This matrix is stored by columns. I mean that in an i-th row of this matrix an i-th column (of a real matrix) is stored. There is an example: i-th row: 1 2 3 4 (in the file). That means that the real matrix has an i-th column: (1 2 3 4)(is transposed). I need to save this matrix in a natural way (by rows) in a new file, which I will then open with FileReader and display with TextArea. Do you know, how to do that? If so, please help =)

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• php codeigniter MySQL search query

  - by kalafun

  I want to create a search query on MySQL database that will consist of 5 different strings typed in from user. I want to query 5 different table columns with these strings. When I for example have input fields like: first name, last name, address, post number, city. How should I query the database that I dont always get all the rows. My query is something like this: SELECT user_id, username from users where a like %?% AND b like %?% AND c like %?% AND d like %?% AND e like %?%; When I exchange the AND for OR I always get all the results which makes sense, and when I use AND I get only the exact matches... Is there any function or statement that would help me with this?

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• Export a MYSQL column to a plain txt file with no headings

  - by Kohl Sharples

  So what I'm trying to do is write a script or CRON job (Linux- CentOS) to export the usernames listed in my wordpress database to a simple .txt file with just on username per line. So with the picture, I would like the .txt file to read like this: Sir_Fluffulus NunjaX007 (Except with all the username in the user_login column.) See screenshot at: http://i.stack.imgur.com/lZQai.png I have found how to export the entire table to a CVS file, but that contains about 10+ fields (Columns) that I DO NOT what to show up in this text file. Can anyone point me in the right direction on how to do this? If it helps, this is going to be for exporting users that have signed up on our website (Wordpress) to a whitelist.txt file for Minecraft. Thanks!

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• Store the day of the week and time

  - by bsiddiqui

  I have a two part question about storing day(s) of the week and time in a database. I'm using Rails 4.0, ruby 2.0.0, and postgres. I have certain events and those events have a schedule. For the event Skydiving for example, for example, I might have Tuesday and Wednesday and 3 pm. 1) Is there a way for me to store the the record for Tuesday and Wednesday in one row or do should I have two records? 2) What is the best way to store the day and time? Is there a way to store day of week and time (not datetime) or should these be separate columns? If they should be separate, how would you store day of week? I was thinking of storing them as integer values (0 for Sunday, 1 for Monday, etc) since that's how wday method for the Time class does it. Any suggestions would be super helpful. Thanks!

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• How can I efficiently retrieve a large number of database settings as PHP variables?

  - by Steven

  Currently all of my script's settings are located in a PHP file which I 'include'. I'm in the process of moving these settings (about 100) to a database table called 'settings'. However I'm struggling to find an efficient way of retrieving all of them into the file. The settings table has 3 columns: ID (autoincrements) name value Two example rows might be: 1 admin_user john 2 admin_email_address [email protected] The only way I can think of retrieving each setting is like this: $result = mysql_query("SELECT value FROM settings WHERE name = 'admin_user'"); $row = mysql_fetch_array($result); $admin_user = $row['value']; $result = mysql_query("SELECT value FROM settings WHERE name = 'admin_email_address'"); $row = mysql_fetch_array($result); $admin_email_address = $row['value']; etc etc Doing it this way will take up a lot of code and will likely be slow. Is there a better way? Thanks.

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• Grouping and retrieving most recent entry in a table for each group

  - by Lisa

  First off, please bear with me if I don't state the SQL question correctly. I have a table that has multiple columns of data. The selection criteria for my table groups based on column 1(order #). There could be multiple items on each order, but the item #'s are not grouped together. Example: Order Customer Order Date Order Time Item Quantity 123456 45 01/02/2010 08:00 140 4 123456 45 01/02/2010 08:30 270 29 123456 45 03/03/2010 09:00 140 6 123456 45 04/02/2010 09:30 140 10 123456 45 04/02/2010 10:00 270 35 What I need is a result like: Order Customer Order Date Order Time Item Quantity 123456 45 04/02/2010 09:30 140 10 123456 45 04/02/2010 10:00 270 35 This result shows that after all the changes the final order includes 10 of Item 140 and 35 of Item 270. Is this possible. python

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• How to parse mathematical expressions involving parentheses

  - by Rob P.

  Please forgive my title, I really don't know how to phrase it better. This isn't a school assignment or anything, but I realize it's a mostly academic question. But, what I've been struggling to do is parse 'math' text and come up with an answer. For Example - I can figure out how to parse '5 + 5' or '3 * 5' - but I fail when I try to correctly chain operations together. (5 + 5) * 3 It's mostly just bugging me that I can't figure it out. If anyone can point me in a direction, I'd really appreciate it. EDIT Thanks for all of the quick responses. I'm sorry I didn't do a better job of explaining. First - I'm not using regular expressions. I also know there are already libraries available that will take, as a string, a mathematical expression and return the correct value. So, I'm mostly looking at this because, sadly, I don't "get it". Second - What I've tried doing (is probably misguided) but I was counting '(' and ')' and evaluating the deepest items first. In simple examples, this worked; but my code is not pretty and more complicated stuff crashes. When I 'calculated' the lowest level, I was modifying the string. So... (5 + 5) * 3 Would turn into 10 * 3 Which would then evaluate to 30 But it just felt 'wrong'. I hope that helps clarify things. I'll certainly check out the links provided.

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• why this with excel sheet reading?

  - by Lalit

  Hi, I am reading the excel sheet from c# interop services cell by cell. where as my excel sheet have Date cells. It generates some double values , I am converting them in date by : double dbl = Convert.ToDouble(((Excel.Range)worksheet.Cells[iRowindex, colIndex_q17]).Value2); string strDate3 = DateTime.FromOADate(dbl).ToShortDateString(); drRow[dtSourceEXLData.Columns[constants.VisualDate]] = strDate3; ok? but some time happening the value of ((Excel.Range)worksheet.Cells[iRowindex,colIndex_q17]).Value2 getting date formate.why this is happeing? plaease guide me. it throws excepion of "input string not in correct format".why it is not generating double value like other cell of same column?

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• Which index is used in select and why?

  - by Lukasz Lysik

  I have the table with zip codes with following columns: id - PRIMARY KEY code - NONCLUSTERED INDEX city When I execute query SELECT TOP 10 * FROM ZIPCodes I get the results sorted by id column. But when I change the query to: SELECT TOP 10 id FROM ZIPCodes I get the results sorted by code column. Again, when I change the query to: SELECT TOP 10 code FROM ZIPCodes I get the results sorted by code column again. And finally when I change to: SELECT TOP 10 id,code FROM ZIPCodes I get the results sorted by id column. My question is in the title of the question. I know which indexes are used in the queries, but my question is, why those indexes are used? I the second query (SELECT TOP 10 id FROM ZIPCodes) wouldn't it be faster if the clusteder index was used? How the query engine chooses which index to use?

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• Store data in an inconvenient table or create a derived table?

  - by user1705685

  I have a certain predefined database structure that I am stuck with. The question is whether this structure is OK for ORM or I whether should add a processing layer that would create a more convenient structure every time something is inserted into the original DB. To simplify, here's what it kind of looks like. I have a person table: PersonId Name And I have a properties table: PersonId PropertyType PropertyValue So, for person John Doe... (1, 'John Doe') ...I could have three properties: (1, 'phone', '555-55-55'), (1, 'email', '[email protected]), (1, 'type', 'employee') By using ORM I would like to get a "person" object that would have properties "name", "phone", "email", "type". Can Propel do that? How efficient is it? Is it a better idea to create a table with columns "phone", "email", "type" and fill it automatically as new rows are inserted into the properties table?

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• Generate unique ID from multiple values with fault tolerance

  - by ojreadmore

  Given some values, I'd like to make a (pretty darn) unique result. $unique1 = generate(array('ab034', '981kja7261', '381jkfa0', 'vzcvqdx2993883i3ifja8', '0plnmjfys')); //now $unique1 == "sqef3452y"; I also need something that's pretty close to return the same result. In this case, 20% of the values is missing. $unique2 = generate(array('ab034', '981kja7261', '381jkfa0', 'vzcvqdx2993883i3ifja8')); //also $unique2 == "sqef3452y"; I'm not sure where to begin with such an algorithm but I have some assumptions. I assume that the more values given, the more accurate the resulting ID – in other words, using 20 values is better than 5. I also assume that a confidence factor can be calculated and adjusted. What would be nice to have is a weight factor where one can say 'value 1 is more important than value 3'. This would require a multidimensional array for input instead of one dimension. I just mashed on the keyboard for these values, but in practice they may be short or long alpha numeric values.

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• Any way to define getters for lazy variables in Javascript arrays?

  - by LLer

  I'm trying to add elements to an array that are lazy-evaluated. This means that the value for them will not be calculated or known until they are accessed. This is like a previous question I asked but for objects. What I ended up doing for objects was Object.prototype.lazy = function(var_name, value_function) { this.__defineGetter__(var_name, function() { var saved_value = value_function(); this.__defineGetter__(var_name, function() { return saved_value; }); return saved_value; }); } lazy('exampleField', function() { // the code that returns the value I want }); But I haven't figured out a way to do it for real Arrays. Arrays don't have setters like that. You could push a function to an array, but you'd have to call it as a function for it to return the object you really want. What I'm doing right now is I created an object that I treat as an array. Object.prototype.lazy_push = function(value_function) { if(!this.length) this.length = 0; this.lazy(this.length++, value_function); } So what I want to know is, is there a way to do this while still doing it on an array and not a fake array?

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• How to coerce type of ActiveRecord attribute returned by :select phrase on joined table?

  - by tribalvibes

  Having trouble with AR 2.3.5, e.g.: users = User.all( :select => "u.id, c.user_id", :from => "users u, connections c", :conditions => ... ) Returns, e.g.: => [#<User id: 1000>] >> users.first.attributes => {"id"=>1000, "user_id"=>"1000"} Note that AR returns the id of the model searched as numeric but the selected user_id of the joined model as a String, although both are int(11) in the database schema. How could I better form this type of query to select columns of tables backing multiple models and retrieving their natural type rather than String ? Seems like AR is punting on this somewhere. How could I coerce the returned types at AR load time and not have to tack .to_i (etc.) onto every post-hoc access?

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• MySQLi String comparisons using keys

  - by asdasd

  I have a table with lets say 2 columns. id number, and value. Value is a string (var char). Lets say i have a number x, and a list of numbers a1, a2, a3, a4, a5..... where x is not in the list. All of these numbers correspond to a unique row in the table. I want to know if the string value for x in the table is contained in one of the string values for any table entry for a1, a2, a3, a4... Lets say i have these rows: x, aaa a1, bbb a2, ccc a3, ddd a4, aaabbbcc then i want somehow a confirmation that yes, the value for x is included in one of the values in my list of numbers (a4 contains x). I know i can do this in a couple queries and shove it down some PHP and get my answer. But can i do this with one query?

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• Error " Index exceeds Matrix dimensions"

  - by Mola

  Hi experts, I am trying to read an excel 2003 file which consist of 62 columns and 2000 rows and then draw 2d dendrogram from 2000 pattern of 2 categories of a data as my plot in matlab. When i run the script, it gives me the above error. I don't know why. Anybody has any idea why i have the above error? My data is here: http://rapidshare.com/files/383549074/data.xls Please delete the 2001 column if you want to use the data for testing. and my code is here: % Script file: cluster_2d_data.m d=2000; n1=22; n2=40; N=62 Data=xlsread('data.xls','A1:BJ2000'); X=Data'; R=1:2000; C=1:2; clustergram(X,'Pdist','euclidean','Linkage','complete','Dimension',2,... 'ROWLABELS',R,'COLUMNLABELS',C,'Dendrogram',{'color',5})

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• Transform LINQ Dataset into a Matrix for export

  - by Mad Halfling

  Hi folks, I've got a data table with columns in which include Item, Category and Value (and others, but those are the only relevant ones for this problem) that I access via LINQ in a C# ASP.Net MVC app. I want to transform these into a matrix and output that as a CSV file to pull into Excel as matrix with the items down the side, the categories across the top and the values in the row cells. However, I don't know how many, or what, categories there will be in this table, nor will there always be a record for each item/category combination. I've written this by looping round, getting my "master category" list, then looking again for each item, filling in either blank or Value, depending on whether the item/category record exists, but as there are currently 27000 records in the table, this isn't as fast as I'd like. Is there a slicker and faster way I can do this, maybe via LINQ (firing into a quicker SQL statement so the DB server can do the leg-work), or will any method essentially come back to what I am doing? Thx MH

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• Getting started with MIT Proto

  - by Charles

  MIT Proto lacks a basic getting started guide. How do I find a shell that accepts commands like (def foo...) and proto -n 1000 -l -m ...? http://groups.csail.mit.edu/stpg/proto.html I can run in my bash shell: ./proto -n 1000 -s 0.1 -T -l "(red (gradient (= (mid) 0)))" I can't figure out how to run e.g. channel.proto: (def channel (src dst width) (let* ((d (distance src dst)) (trail (<= (+ (gradient src) (gradient dst)) (+ d 0.01))) ;; float error ;; (trail (= (+ (gradient src) (gradient dst)) d)) ) (dilate trail width))) ;; To see a channel calculated from geometric primitives, run: ;; proto -n 1000 -l -m -s 0.5 "(blue (channel (sense 1) (sense 2) 10))" ;; click on a device and hit 't' to set up the source, then click on ;; another device and hit 'y' to designate the destination. At first ;; every device will be blue, but then it should clear and you should ;; see a thick blue path connecting the two devices you selected. Thanks! P.S. Somebody please tag this mit-proto. I can't.

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• How to Audit Database Activity without Performance and Scalability Issues?

  - by GotoError

  I have a need to do auditing all database activity regardless of whether it came from application or someone issuing some sql via other means. So the auditing must be done at the database level. The database in question is Oracle. I looked at doing it via Triggers and also via something called Fine Grained Auditing that Oracle provides. In both cases, we turned on auditing on specific tables and specific columns. However, we found that Performance really sucks when we use either of these methods. Since auditing is an absolute must due to regulations placed around data privacy, I am wondering what is best way to do this without significant performance degradations. If someone has Oracle specific experience with this, it will be helpful but if not just general practices around database activity auditing will be okay as well.

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• Python - How to wake up a sleeping process- multiprocessing?

  - by user1162512

  I need to wake up a sleeping process ? The time (t) for which it sleeps is calculated as t = D/S . Now since s is varying, can increase or decrease, I need to increase/decrease the sleeping time as well. The speed is received over a UDP procotol. So, how do I change the sleeping time of a process, keeping in mind the following:- If as per the previous speed `S1`, the time to sleep is `(D/S1)` . Now the speed is changed, it should now sleep for the new time,ie (D/S2). Since, it has already slept for D/S1 time, now it should sleep for D/S2 - D/S1. How would I do it? As of right now, I'm just assuming that the speed will remain constant all throughout the program, hence not notifying the process. But how would I do that according to the above condition? def process2(): p = multiprocessing.current_process() time.sleep(secs1) # send some packet1 via UDP time.sleep(secs2) # send some packet2 via UDP time.sleep(secs3) # send some packet3 via UDP Also, as in threads, 1) threading.activeCount(): Returns the number of thread objects that are active. 2) threading.currentThread(): Returns the number of thread objects in the caller's thread control. 3) threading.enumerate(): Returns a list of all thread objects that are currently active. What are the similar functions for getting activecount, enumerate in multiprocessing?

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• How to store data to Excel from DataSet without going cell-by-cell?

  - by Jason Barnwell

  Duplicate of: What’s the simplest way to import a System.Data.DataSet into Excel? Using c# under VS2008, we can create an excel app, workbook, and then worksheet fine by doing this: Application excelApp = new Application(); Workbook excelWb = excelApp.Workbooks.Add(template); Worksheet excelWs = (Worksheet)this.Application.ActiveSheet; Then we can access each cell by "excelWs.Cells[i,j]" and write/save without problems. However with large numbers of rows/columns, we are expecting a loss in efficiency. Is there a way to "data bind" from a DataSet object into the worksheet without using the cell-by-cell approach? Most of the methods we have seen at some point revert to the cell-by-cell approach. Thanks for any suggestions.

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