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  • filter duplicates in SQL join

    - by Will
    When using a SQL join, is it possible to keep only rows that have a single row for the left table? For example: select * from A, B where A.id = B.a_id; a1 b1 a2 b1 a2 b2 In this case, I want to remove all except the first row, where a single row from A matched exactly 1 row from B. I'm using MySQL.

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  • Python: mysqldb install error

    - by Grenko
    So i've been pulling my hair out trying to install the mysqldb package. When i run the build i get a long transcript of errors, heres just part of it, i would posit it all but its huge list of errors [rv@med240-183 MySQL-python-1.2.3c1]$ sudo python setup.py build [sudo] password for rv: running build running build_py copying MySQLdb/release.py -> build/lib.linux-i686-2.6/MySQLdb running build_ext building '_mysql' extension gcc -pthread -fno-strict-aliasing -DNDEBUG -O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m32 -march=i586 -mtune=generic -fasynchronous-unwind-tables -D_GNU_SOURCE -fPIC -fPIC -Dversion_info=(1,2,3,'gamma',1) -D__version__=1.2.3c1 -I/usr/include/mysql -I/usr/include/python2.6 -c _mysql.c -o build/temp.linux-i686-2.6/_mysql.o -g -pipe -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m32 -fasynchronous-unwind-tables -D_GNU_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE_SOURCE -fno-strict-aliasing -fwrapv -fPIC -DUNIV_LINUX _mysql.c:36:23: error: my_config.h: No such file or directory _mysql.c:38:19: error: mysql.h: No such file or directory Any ideas?

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  • Creating a Group of Groups in Django

    - by Greg
    I'm creating my own Group model; I'm not referring to the builtin Group model. I want each hroup to be a member of another group (it's parent), but there is the one "top" group that doesn't have a parent group. The admin interface won't let me create a group without entering a parent. I get the error personnel_group.parent_id may not be NULL. My Group model looks like this: class Group(models.Model): name = models.CharField(max_length=50) parent = models.ForeignKey('self', blank=True, null=True) order = models.IntegerField() icon = models.ImageField(upload_to='groups', blank=True, null=True) description = models.TextField(blank=True, null=True) How can I accomplish this? Thanks.

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  • Search Oracle date type column with hibernate, seach by everything in that day - ignore the time.

    - by Setori
    hi there <property name="batchCreatedDate" type="java.util.Date"> <meta attribute="field-description">batch create date</meta> <column name="BATCH_CREATED_DATE" length="7" not-null="true" /> </property> table column type is BATCH_CREATED_DATE DATE NOT NULL With the data in that date column being similar to this '2010-05-13 14:56:36.0' now I want to search for all items within the 24 hours of 2010-05-13, currently my call only returns all items with date "2010-05-13 14:56:36.0" exactly. What would my HQL statement look like to hand this kind of scenario? Thank you so much

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  • Creating a Web Service to automatically get information

    - by Sean P
    I want to create some sort of method of creating a web service that will run automatically and run DB queries and some API calls which will then store data that I can use/call without taking the processing or time penalty of doing it every time a user access my web service. Is this possible? If so, point me in the right direction on how to implement something like this Using vb.net and ASP.net Thanks in advance!!

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  • What data is actually stored in a B-tree database in CouchDB?

    - by Andrey Vlasovskikh
    I'm wondering what is actually stored in a CouchDB database B-tree? The CouchDB: The Definitive Guide tells that a database B-tree is used for append-only operations and that a database is stored in a single B-tree (besides per-view B-trees). So I guess the data items that are appended to the database file are revisions of documents, not the whole documents: +---------|### ... | | +------|###|------+ ... ---+ | | | | +------+ +------+ +------+ +------+ | doc1 | | doc2 | | doc1 | ... | doc1 | | rev1 | | rev1 | | rev2 | | rev7 | +------+ +------+ +------+ +------+ Is it true? If it is true, then how the current revision of a document is determined based on such a B-tree? Doesn't it mean, that CouchDB needs a separate "view" database for indexing current revisions of documents to preserve O(log n) access? Wouldn't it lead to race conditions while building such an index? (as far as I know, CouchDB uses no write locks).

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  • Error in connection in ruby.

    - by piemesons
    require 'rubygems' require 'mysql' db = Mysql.connect('localhost', 'root', '', 'mohit') //db.rb:4: undefined method `connect' for Mysql:Class (NoMethodError) //undefined method `real_connect' for Mysql:Class (NoMethodError) db.query("CREATE TABLE people ( id integer primary key, name varchar(50), age integer)") db.query("INSERT INTO people (name, age) VALUES('Chris', 25)") begin query = db.query('SELECT * FROM people') puts "There were #{query.num_rows} rows returned" query.each_hash do |h| puts h.inspect end rescue puts db.errno puts db.error end error i am geting is: undefined method `connect' for Mysql:Class (NoMethodError) OR undefined method `real_connect' for Mysql:Class (NoMethodError) EDIT return value of Mysql.methods ["private_class_method", "inspect", "name", "tap", "clone", "public_methods", "object_id", "__send__", "method_defined?", "instance_variable_defined?", "equal?", "freeze", "extend", "send", "const_defined?", "methods", "ancestors", "module_eval", "instance_method", "hash", "autoload?", "dup", "to_enum", "instance_methods", "public_method_defined?", "instance_variables", "class_variable_defined?", "eql?", "constants", "id", "instance_eval", "singleton_methods", "module_exec", "const_missing", "taint", "instance_variable_get", "frozen?", "enum_for", "private_method_defined?", "public_instance_methods", "display", "instance_of?", "superclass", "method", "to_a", "included_modules", "const_get", "instance_exec", "type", "<", "protected_methods", "<=>", "class_eval", "==", "class_variables", ">", "===", "instance_variable_set", "protected_instance_methods", "protected_method_defined?", "respond_to?", "kind_of?", ">=", "public_class_method", "to_s", "<=", "const_set", "allocate", "class", "new", "private_methods", "=~", "tainted?", "__id__", "class_exec", "autoload", "untaint", "nil?", "private_instance_methods", "include?", "is_a?"] return value of Mysql.methods(false) is []... blank array

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  • why does cx_oracle execute() not like my string now?

    - by Frank Stallone
    I've downloaded cx_oracle some time ago and wrote a script to convert data to XML. I've had to reisntall my OS and grabbed the latest version of cx_Oracle (5.0.3) and all of the sudden my code is broken. The first thing was that cx_Oracle.connect wanted unicode rather string for the username and password, that was very easy to fix. But now it keeps failing on the cursor.execute and tells me my string is not a string even when type() tells me it is a string. Here is a test script I initally used ages ago and worked fine on my old version but does not work on cx_Oracle now. import cx_Oracle ip = 'url.to.oracle' port = 1521 SID = 'mysid' dsn_tns = cx_Oracle.makedsn(ip, port, SID) connection = cx_Oracle.connect(u'name', u'pass', dsn_tns) cursor = connection.cursor() cursor.arraysize = 50 sql = "select isbn, title_code from core_isbn where rownum<=20" print type(sql) cursor.execute(sql) for isbn, title_code in cursor.fetchall(): print "Values from DB:", isbn, title_code cursor.close() connection.close() When I run that I get: Traceback (most recent call last): File "C:\NetBeansProjects\Python\src\db_temp.py", line 48, in cursor.execute(sql) TypeError: expecting None or a string Does anyone know what I may be doing wrong?

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  • How to structure the tables of a very simple blog in MySQL?

    - by Programmer
    I want to add a very simple blog feature on one of my existing LAMP sites. It would be tied to a user's existing profile, and they would be able to simply input a title and a body for each post in their blog, and the date would be automatically set upon submission. They would be allowed to edit and delete any blog post and title at any time. The blog would be displayed from most recent to oldest, perhaps 20 posts to a page, with proper pagination above that. Other users would be able to leave comments on each post, which the blog owner would be allowed to delete, but not pre-moderate. That's basically it. Like I said, very simple. How should I structure the MySQL tables for this? I'm assuming that since there will be blog posts and comments, I would need a separate table for each, is that correct? But then what columns would I need in each table, what data structures should I use, and how should I link the two tables together (e.g. any foreign keys)? I could not find any tutorials for something like this, and what I'm looking to do is really offer my users the simplest version of a blog possible. No tags, no moderation, no images, no fancy formatting, etc. Just a simple diary-type, pure-text blog with commenting by other users.

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  • How to use multiple database in a PHP web application?

    - by Harish
    I am making a PHP web Application in which i am using MySQL as database server, i want to make backup of some tables from one database to another database(with that tables in it). i have created two different connection, but the table is not updated. $dbcon1 = mysql_connect(DB_SERVER,DB_USER,DB_PASSWORD) or die(mysql_error()); $dbase1 = mysql_select_db(TEMP_DB_NAME,$dbcon)or die(mysql_error()); $query1=mysql_query("SELECT * FROM emp"); while($row = mysql_fetch_array($query1, MYSQL_NUM)) { $dbcon2 = mysql_connect(DB_SERVER,DB_USER,DB_PASSWORD) or die(mysql_error()); $dbase2 = mysql_select_db(TEMP_DB_NAME2,$dbcon)or die(mysql_error()); mysql_query("INSERT INTO backup_emp VALUES(null,'$row[1]',$row[2])"); mysql_close($dbcon2); } the code above is taking the data of emp from first database, and updataing it into another backup_emp table of another database. the code is not working properly, is there any other way of doing this...please help.

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  • PHP-MySQL: Arranging rows from seperate tables together/Expression to determine row origin

    - by Koroviev
    I'm new to PHP and have a two part question. I need to take rows from two separate tables, and arrange them in descending order by their date. The rows do not correspond in order or number and have no relationship with each other. ---EDIT--- They each contain updates on a site, one table holds text, links, dates, titles etc. from a blog. The other has titles, links, specifications, etc. from images. I want to arrange some basic information (title, date, small description) in an updates section on the main page of the site, and for it to be in order of date. Merging them into one table and modifying it to suit both types isn't what I'd like to do here, the blog table is Wordpress' standard wp_posts and I don't feel comfortable adding columns to make it suit the image table too. I'm afraid it could clash with upgrading later on and it seems like a clumsy solution (but that doesn't mean I'll object if people here advise me it's the best solution). ------EDIT 2------ Here are the DESCRIBES of each table: mysql> describe images; +---------+--------------+------+-----+-------------------+----------------+ | Field | Type | Null | Key | Default | Extra | +---------+--------------+------+-----+-------------------+----------------+ | id | int(11) | NO | PRI | NULL | auto_increment | | project | varchar(255) | NO | | NULL | | | title | varchar(255) | NO | | NULL | | | time | timestamp | NO | | CURRENT_TIMESTAMP | | | img_url | varchar(255) | NO | | NULL | | | alt_txt | varchar(255) | YES | | NULL | | | text | text | YES | | NULL | | | text_id | int(11) | YES | | NULL | | +---------+--------------+------+-----+-------------------+----------------+ mysql> DESCRIBE wp_posts; +-----------------------+---------------------+------+-----+---------------------+----------------+ | Field | Type | Null | Key | Default | Extra | +-----------------------+---------------------+------+-----+---------------------+----------------+ | ID | bigint(20) unsigned | NO | PRI | NULL | auto_increment | | post_author | bigint(20) unsigned | NO | | 0 | | | post_date | datetime | NO | | 0000-00-00 00:00:00 | | | post_date_gmt | datetime | NO | | 0000-00-00 00:00:00 | | | post_content | longtext | NO | | NULL | | | post_title | text | NO | | NULL | | | post_excerpt | text | NO | | NULL | | | post_status | varchar(20) | NO | | publish | | | comment_status | varchar(20) | NO | | open | | | ping_status | varchar(20) | NO | | open | | | post_password | varchar(20) | NO | | | | | post_name | varchar(200) | NO | MUL | | | | to_ping | text | NO | | NULL | | | pinged | text | NO | | NULL | | | post_modified | datetime | NO | | 0000-00-00 00:00:00 | | | post_modified_gmt | datetime | NO | | 0000-00-00 00:00:00 | | | post_content_filtered | text | NO | | NULL | | | post_parent | bigint(20) unsigned | NO | MUL | 0 | | | guid | varchar(255) | NO | | | | | menu_order | int(11) | NO | | 0 | | | post_type | varchar(20) | NO | MUL | post | | | post_mime_type | varchar(100) | NO | | | | | comment_count | bigint(20) | NO | | 0 | | +-----------------------+---------------------+------+-----+---------------------+----------------+ ---END EDIT--- I can do this easily with a single table like this (I include it here in case I'm using an over-elaborate method without knowing it): $content = mysql_query("SELECT post_title, post_text, post_date FROM posts ORDER BY post_date DESC"); while($row = mysql_fetch_array($content)) { echo $row['post_date'], $row['post_title'], $row['post_text']; } But how is it possible to call both tables into the same array to arrange them correctly? By correctly, I mean that they will intermix their echoed results based on their date. Maybe I'm looking at this from the wrong perspective, and calling them to a single array isn't the answer? Additionally, I need a way to form a conditional expression based on which table they came from, so that rows from table 1 get echoed differently than rows from table 2? I want results from table 1 to be echoed differently (with different strings concatenated around them, I mean) for the purpose of styling them differently than those from table two. And vice versa. I know an if...else statement would work here, but I have no idea how can I write the expression that would determine which table the row is from. All and any help is appreciated, thanks.

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  • Syntax Error with MySQL 5.1 Server

    - by Mr.Z
    I am trying to connect to a server remotely using the command line client window. I am using MySQL 5.1 and I do not know why I am getting syntax error. If you can help me, that would be much appreciated. username as user password as pass hostname as example.com I have tried: mysql> -u user -h example.com -p ; mysql> -h example.com -u user -p ; I have looked at the reference manual and other verisons of remote connection with Server 5.1 but I can't see the syntax error.

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  • "SQLSTATE[23000]: Integrity constraint violation" in Doctrine

    - by rags
    Hi, i do get an Integrity constraint violation for Doctrine though i really can't see why. Schema.yml User: columns: id: type: integer primary: true autoincrement: true username: type: varchar(64) notnull: true email: type: varchar(128) notnull: true password: type: varchar(128) notnull: true relations: Websites: class: Website local: id foreign: owner type: many foreignType: one onDelete: CASCADE Website: columns: id: type: integer primary: true autoincrement: true active: type: bool owner: type: integer notnull: true plz: type: integer notnull: true longitude: type: double(10,6) notnull: true latitude: type: double(10,6) notnull: true relations: Owner: type: one foreignType: many class: User local: owner foreign: id And here's my data Fixtures (data.yml) Model_User: User_1: username: as email: as****.com password: ***** Model_Website: Website_1: active: true plz: 34222 latitude: 13.12 longitude: 3.56 Owner: User_1

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  • Prroblem with ObjectDelete() in Entity Framework 4

    - by Tom
    I got two entities: public class User : Entity { public virtual string Username { get; set; } public virtual string Email { get; set; } public virtual string PasswordHash { get; set; } public virtual List<Photo> Photos { get; set; } } and public class Photo : Entity { public virtual string FileName { get; set; } public virtual string Thumbnail { get; set; } public virtual string Description { get; set; } public virtual int UserId { get; set; } public virtual User User { get; set; } } When I try to delete the photo it works fine for the DB (record gets romoved from the table) but it doesnt for the Photos collection in the User entity (I can still see that photo in user.Photos). This is my code. What I'm doing wrong here? Changing entity properties works fine. When I change photo FileName for example it gets updated in DB and in user.Photos. var photo = SelectById(id); Context.DeleteObject(photo); Context.SaveChanges(); var user = GetUser(userName); // the photo I have just deleted is still in user.Photos also tried this but getting same results: var photo = user.Photos.First(); Context.DeleteObject(photo); Context.SaveChanges();

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  • Non-normalized association with legacy tables in Rails and ActiveRecord

    - by Thomas Holmström
    I am building a Rails application accessing a legacy system. The data model contains Customers which can have one or more Subscriptions. A Subscription always belong to one and only one Customer. Though not needed, this association is represented through a join table "subscribes", which do not have an id column: Column | Type | Modifiers -----------------+---------+----------- customer_id | integer | not null subscription_id | integer | not null I have this coded as a has_and_belongs_to_many declarations in both Customer and Subscription class Customer < Activerecord::Base has_and_belongs_to_many :subscriptions, :join_table => "subscribes", :foreign_key => "customer_id", :association_foreign_key => "subscription_id" end class Subscription < Activerecord::Base has_and_belongs_to_many :customers, :join_table => "subscribes", :foreign_key => "subscription_id", :association_foreign_key => "customer_id" end The problem I have is that there can only ever be one customer for each subscription, not many, and the join table will always contain at most one row with a certain customer_id. And thus, I don't want the association "customers" on a Subscription which returns an array of (at most one) Customer, I really do want the relation "customer" which returns the Customer associated. Is there any way to force ActiveRecord to make this a 1-to-N relation even though the join table itself seems to make it an N-to-M relation? --Thomas

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  • why is there extra using where in execution plan of query

    - by user366534
    I see plan of query: EXPLAIN SELECT * FROM `subscribers` WHERE state =4 AND date_added < '2010-12-23 11:47:45' It shows: id select_type table type possible_keys key key_len ref rows Extra 1 SIMPLE subscribers range state_date_added state_date_added 9 NULL 8 Using where Here is indexes of table: Table Non_unique Key_name Seq_in_index Column_name Collation Cardinality Sub_part Packed Null Index_type Comment subscribers 0 PRIMARY 1 subscriber_id A 382039 NULL NULL BTREE subscribers 0 email_list_id 1 email_address A 191019 NULL NULL BTREE subscribers 0 email_list_id 2 list_id A 382039 NULL NULL BTREE subscribers 1 FK_list_id 1 list_id A 10 NULL NULL BTREE subscribers 1 state_date_added 1 state A 12 NULL NULL BTREE subscribers 1 state_date_added 2 date_added A 8128 NULL NULL BTREE The last two lines describes index what is supposed for the query. Why is there in extra column using where? Even If I fetch only state and date_added column, it has in extra column: Using where; Using index. I understand why it has using index, but I don't understand Using where here.

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  • Explain this SQL query in plain English.

    - by Kevinniceguy
    Please explain, in plain English, what question this SQL query answers: 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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  • Copy VSS structure to server with asp.net

    - by Tyzak
    i want to copy the structure (with the documents) from our vss server to an webserver. Therefore i want to create an application which is on this webserver. i want to use asp.net. i don't know what exactly i need therefore : I have to build somekind of connection? then go throw the structure and copy it somehow : ? important: i want to copy the documents with the right creation date ( it changes when i just copy the doc.) are there APIs for asp.net <- vss?

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  • How to find date ranges in records with consecutive dates and duplicate data

    - by alan s
    There's probably any easy solution for this, but I can't see it. I have a table with consecutive dates and often duplicate associated data for several of these consecutive dates: Date Col1 Col2 5/13/2010 1 A 5/14/2010 1 A 5/15/2010 2 B 5/16/2010 1 A 5/17/2010 1 A 5/18/2010 3 C 5/19/2010 3 C 5/20/2010 3 C Using MS T-SQL, I wish to find the start and end dates for each run of distinct Col1 and Col2 values: StartDate EndDate Col1 Col2 5/13/2010 5/14/2010 1 A 5/15/2010 5/15/2010 2 B 5/16/2010 5/17/2010 1 A 5/18/2010 5/20/2010 3 C Assumptions: There are never any missing dates. Col1 and Col2 are not null. Any ideas - preferably that don't use cursors? Many thanks, -alan

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  • Setting 0/1-to-1 relationship in SQLAlchemy?

    - by Timmy
    is there a proper way of setting up a 0/1-to-1 relationship? i want to be able to check if the related item exists without creating it: if item.relationship is None: item.relationship = item2() but it creates the insert statements on the if statement

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  • Mysql random rows

    - by n00b
    please read the whole question... 90% of you dont seem to do that and some of you only read the title obviously... and if you dont know the solution, dont answer - i wont have to downvote you -.-'' im entertaining the idea of getting random rows directly from mysql. what i found was SELECT * FROM tablename WHERE somefield='something' ORDER BY RAND() LIMIT 5 but even i see how slow that would be.. is the only way to do this doing something like SELECT * FROM tablename WHERE somefield='something' LIMIT RAND(aincrementvalue-5), 1 5 times? or is there a way that i with my little knowlege of databases cant come up with ? (no i dont want random indexes. i hate the idea of them...) @commenters - please first look, then think, then look again, think again and then post. i wont point fingers but i dislike stupid comments and why i think random indexes are a nasty hack ? it doesnt give you random results. it gives you x results from a random index in a predefined order its like a gapless id only in the wrong order if you fetch by 1 row and get true randomness you fall back to my method but with an additional junk field finally the reason the field exists is only to serve as a helper to something that can be done without it with almost same performance (but the quality (randomness) is better), so it is a nasty hack ;) i solved it, look @ my answer... if you think its incorrect please tell me :)

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  • How to efficiently store and update binary data in Mongodb?

    - by Rocketman
    I am storing a large binary array within a document. I wish to continually add bytes to this array and sometimes change the value of existing bytes. I was looking for some $append_bytes and $replace_bytes type of modifiers but it appears that the best I can do is $push for arrays. It seems like this would be doable by performing seek-write type operations if I had access somehow to the underlying bson on disk, but it does not appear to me that there is anyway to do this in mongodb (and probably for good reason). If I were instead to just query this binary array, edit or add to it, and then update the document by rewriting the entire field, how costly will this be? Each binary array will be on the order of 1-2MB, and updates occur once every 5 minutes and across 1000s of documents. Worse, yet there is no easy way to spread these out (in time) and they will usually be happening close to one another on the 5 minute intervals. Does anyone have a good feel for how disastrous this will be? Seems like it would be problematic. An alternative would be to store this binary data as separate files on disk, implement a thread pool to efficiently manipulate the files on disk, and reference the filename from my mongodb document. (I'm using python and pymongo so I was looking at pytables). I'd prefer to avoid this though if possible. Is there any other alternative that I am overlooking here? Thanks in advnace.

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