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  • Difference between "and" and "where" in joins

    - by Midhat
    Whats the difference between SELECT DISTINCT field1 FROM table1 cd JOIN table2 ON cd.Company = table2.Name and table2.Id IN (2728) and SELECT DISTINCT field1 FROM table1 cd JOIN table2 ON cd.Company = table2.Name where table2.Id IN (2728) both return the same result and both have the same explain output

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  • Is SQLlite strong enough to use as wordpress database ?

    - by justjoe
    i'm just curious. so i ask this particular question about SQLite. I haven't use this type of database extensively. but care to explain what is the basic different between SQLite and Mysql ? The reason behind all of this is i just want to know whether it possible to use it to store wordpress data and act as a database ?

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  • XML Import how would you do it?

    - by Rico
    XML is used as one of our main integration points. it comes over by many clients at a time but too many clients importing at the same time can slow down our database to a crawl. Someone has to have solved a problem like this. I am basically using VB to parse through the data and import what i want and don't want. Is there a better way?

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  • Create an index only on certain rows in mysql

    - by dhruvbird
    So, I have this funny requirement of creating an index on a table only on a certain set of rows. This is what my table looks like: USER: userid, friendid, created, blah0, blah1, ..., blahN Now, I'd like to create an index on: (userid, friendid, created) but only on those rows where userid = friendid. The reason being that this index is only going to be used to satisfy queries where the WHERE clause contains "userid = friendid". There will be many rows where this is NOT the case, and I really don't want to waste all that extra space on the index. Another option would be to create a table (query table) which is populated on insert/update of this table and create a trigger to do so, but again I am guessing an index on that table would mean that the data would be stored twice. How does mysql store Primary Keys? I mean is the table ordered on the Primary Key or is it ordered by insert order and the PK is like a normal unique index? I checked up on clustered indexes (http://dev.mysql.com/doc/refman/5.0/en/innodb-index-types.html), but it seems only InnoDB supports them. I am using MyISAM (I mention this because then I could have created a clustered index on these 3 fields in the query table). I am basically looking for something like this: ALTER TABLE USERS ADD INDEX (userid, friendid, created) WHERE userid=friendid

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  • Where to start with the development of first database driven Web App (long question)?

    - by Ryan
    Hi all, I've decided to develop a database driven web app, but I'm not sure where to start. The end goal of the project is three-fold: 1) to learn new technologies and practices, 2) deliver an unsolicited demo to management that would show how information that the company stores as office documents spread across a cumbersome network folder structure can be consolidated and made easier to access and maintain and 3) show my co-workers how Test Drive Development and prototyping via class diagrams can be very useful and reduces future maintenance headaches. I think this ends up being a basic CMS to which I have generated a set of features, see below. 1) Create a database to store the site structure (organized as a tree with a 'project group'-project structure). 2) Pull the site structure from the database and display as a tree using basic front end technologies. 3) Add administrator privileges/tools for modifying the site structure. 4) Auto create required sub pages* when an admin adds a new project. 4.1) There will be several sub pages under each project and the content for each sub page is different. 5) add user privileges for assigning read and write privileges to sub pages. What I would like to do is use Test Driven Development and class diagramming as part of my process for developing this project. My problem; I'm not sure where to start. I have read on Unit Testing and UML, but never used them in practice. Also, having never worked with databases before, how to I incorporate these items into the models and test units? Thank you all in advance for your expertise.

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  • Get top 'n' records by report_id

    - by Skudd
    I have a simple view in my MSSQL database. It consists of the following fields: report_id INT ym VARCHAR -- YYYY-MM keyword VARCHAR(MAX) visits INT I can easily get the top 10 keyword hits with the following query: SELECT TOP 10 * FROM top_keywords WHERE ym BETWEEN '2010-05' AND '2010-05' ORDER BY visits DESC Now where it gets tricky is where I have to get the top 10 records for each report_id in the given date range (ym BETWEEN @start_date AND @end_date). How would I go about getting the top 10 for each report_id? I've stumbled across suggestions involving the use of ROW_NUMBER() and RANK(), but have been vastly unsuccessful in their implementation.

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  • Require reasonably random results from an SQL SELECT query within a Joomla article (Cache enabled)

    - by Shrinivas
    Setup: Joomla website on LAMP stack I have a MySQL table containing some records, these are queried by a simple SELECT on the Joomla article, as pasted below. This specific Joomla website has Caching turned on in Joomla's Global Configuration. I need to randomize the order in which I display the resultset, each time the page is loaded. Regular php/mysql would offer me two approaches for this: 1. use 'order by RAND()' or any of a number of methods to allow a SELECT query to return reasonably random results. 2. once php gets the result from the SELECT into an array, shuffle the array to get a reasonably random order of array items. However, as this Joomla instance has Caching turned ON in its Global Configuration, either of the above approaches fails. The first time I load the page the order is randomized, however any further reloads do not cause the order to change, as the page is delivered from cache. The instant the Cache is disabled, both approaches (shuffle/order by rand) work perfectly. What am I missing? How do I override the Global Cache for this specific article? A very simple requirement, that is met by both php and mysql reasonably well, is blocked by the Joomla Cache that I cannot turn off. The php that returns results from the database. <pre> $db = JFactory::getDBO(); $select = "SELECT id FROM jos_mytable;"; //order by RAND() $db->setQuery($select); echo $db->getQuery(); //Show me the Query! $rows = $db->loadObjectList(); //shuffle($rows); foreach($rows as $row) { echo "$row->id"; }

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  • MSSQL. Compare columns in two tables.

    - by maxt3r
    Hi, i've recently done a migration from a really old version of some application to the current version and i faced some problems while migrating databases. I need a query that could help me to compare columns in two tables. I mean not the data in rows, i need to compare the columns itself to figure out, what changes in table structure i've missed.

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  • how to select distinct rows for a column

    - by Satoru.Logic
    Hi, all. I have a table x that's like the one bellow: id | name | observed_value | 1 | a | 100 | 2 | b | 200 | 3 | b | 300 | 4 | a | 150 | 5 | c | 300 | I want to make a query so that in the result set I have exactly one record for one name: (1, a, 100) (2, b, 200) (5, c, 300) If there are multiple records corresponding to a name, say 'a' in the table above, I just pick up one of them. In my current implementation, I make a query like this: select x.* from x , (select distinct name, min(observed_value) as minimum_val from x group by name) x1 where x.name = x1.name and x.observed_value = x1.observed_value; But I think there may be some better way around, please tell me if you know, thanks in advance.

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  • What is the difference between check and foreign key?

    - by GigaPr
    Hi, i am quite confused about the difference between a FOREIGN KEY and CHECK constraint. they appear to me to achieve the same result. I mean I could create a table and enforce a Foreign key on another table, but i could create a CHECK to ensure the value in in another table. What is the difference and when to use the one or the other? thanks

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  • Timeout not working in SQL Connection

    - by carlos
    I have this simple code to test that a DB is ready: Function testlocalcon() As Boolean Dim constr As String = _clconstr Try Using t As New SqlConnection() constr = constr & " ; Connect Timeout=1" If Not t.State = Data.ConnectionState.Open Then t.ConnectionString = constr t.Open() If t.State = Data.ConnectionState.Open Then Return True Else Return False End If Else Return True End If End Using Catch ex As Exception Return False End Try End Function I do not want to execute a query, just to check the connection, but no matter what the time out parameter is ignored. I search here (Stackoverflow) and internet and found nothing in how to fix this. Any one else have this problem? Or, are there any other ideas on how to let the application know that the DB is ready?

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  • How to differenciate two tables

    - by Nemat
    Hi friends.... I have two tables.I want to get all records from one table that are different from the records in second table. For eg. if we have four records in first table like A,B,C,D and three records in second table thats A,B,C then the answer of query should be D. I have tried "EXCEPT" operator but it doesnt work fine.Kindly help me in writing correct query for the given problem. Any help is appreciated.... Thanks in Advance Nemat

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  • mysql join table - selecting the newest row

    - by cmancre
    Hi, I have the following two MySQL tables TABLE NAMES NAME_ID NAME 1 name1 2 name2 3 name3 TABLE STATUS STATUS_ID NAME_ID TIMESTAMP 1 1 2010-12-20 12:00 2 2 2010-12-20 10:00 3 3 2010-12-20 10:30 4 3 2010-12-20 14:00 I would like to select all info from table NAMES and add most recent correspondent TIMESTAMP column from table STATUS RESULT NAME_ID NAME TIMESTAMP 1 name1 2010-12-20 12:00 2 name2 2010-12-20 10:00 3 name3 2010-12-20 14:00 Am stuck on this one. How do I left join only on the newer timestamp?

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  • Want to check fields for data fast.

    - by Tom
    We have a database setup that consists of two parts: a static structure, and dynamic additions. For each database, the dynamic can be different, and sometimes we don't have data for all the dynamic fields. Rigt now, we check for empties by looking at the total count of records in the entire table, but we want to move to a more refined method of checking for empties if possible. Is it possible to quickly check through several hundred fields and see which ones are empty and which ones are populated?

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  • SqlCeCommand ExecuteNonQuery performance issue

    - by Michael
    I've been asked to resolve an issue with a .Net/SqlServerCe application. Specifically, after repeated inserts against the db, performance becomes increasingly degraded. In one instance at ~200 rows, in another at ~1000 rows. In the latter case the code being used looks like this: Dim cm1 As System.Data.SqlServerCe.SqlCeCommand = cn1.CreateCommand cm1.CommandText = "INSERT INTO Table1 Values(?,?,?,?,?,?,?,?,?,?,?,?,?)" For j = 0 To ds.Tables(0).Rows.Count - 1 'this is 3110 For i = 0 To 12 cm1.Parameters(tbl(i, 0)).Value = Vals(j,i) 'values taken from a different db Next cm1.ExecuteNonQuery() Next The specifics aren't super important (like what 'tbl' is, etc) but rather whether or not this code should be expected to handle this number of inserts, or if the crawl I'm witnessing is to be expected.

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  • Selecting distinct values from mysql with largest timestamp

    - by user987048
    I am building a mail system. The inbox is only supposed to grab the last message (one with the highest time value) of a concatenation of user and sender, where the user or sender is the user ID. Here is the table structure: CREATE TABLE IF NOT EXISTS `mail` ( `user` int(11) NOT NULL, `sender` int(11) NOT NULL, `body` text NOT NULL, `new` enum('0','1') NOT NULL default '1', `time` int(11) NOT NULL, KEY `user` (`user`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8; So, with a table with the following data: user sender new time ***************************************** 1 0 0 5 1 0 0 6 2 1 0 7 1 0 1 8 1 2 0 9 1 0 1 11 1 2 1 12 I want to select the following: WHERE USER OR SENDER = X (in this case, 1) user sender new time ***************************************** 2 1 0 7 1 2 0 9 1 0 1 11 How would I go about doing something like this?

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  • Why is it possible to enumerate a LinqToSql query after calling Dispose() on the DataContext?

    - by DanM
    I'm using the Repository Pattern with some LinqToSql objects. My repository objects all implement IDisposable, and the Dispose() method does only thing--calls Dispose() on the DataContext. Whenever I use a repository, I wrap it in a using person, like this: public IEnumerable<Person> SelectPersons() { using (var repository = _repositorySource.GetNew<Person>(dc => dc.Person)) { return repository.GetAll(); } } This method returns an IEnumerable<Person>, so if my understanding is correct, no querying of the database actually takes place until Enumerable<Person> is traversed (e.g., by converting it to a list or array or by using it in a foreach loop), as in this example: var persons = gateway.SelectPersons(); // Dispose() is fired here var personViewModels = ( from b in persons select new PersonViewModel { Id = b.Id, Name = b.Name, Age = b.Age, OrdersCount = b.Order.Count() }).ToList(); // executes queries In this example, Dispose() gets called immediately after setting persons, which is an IEnumerable<Person>, and that's the only time it gets called. So, a couple questions: How does this work? How can a disposed DataContext still query the database for results when I walk the IEnumerable<Person>? What does Dispose() actually do? I've heard that it is not necessary (e.g., see this question) to dispose of a DataContext, but my impression was that it's not a bad idea. Is there any reason not to dispose of it?

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  • Worpress WorkFlow Modfications

    - by blgnklc
    Hi All WordPress Lovers, I would like to ask a help about Zensor which is a plugin that you publish a post then a moderator approves the post to be published on the wordpress blog site. When a post is awating for approval, each awaiting post is appearing "waiting moderation". But, I dont want any link appears before moderator approval. Actually I found the joing sentence below; 1- Must be added to the end of JOIN part of any query: LEFT JOIN wp_zensor ON ID = wp_zensor.post_id 2- Must be added to the end of WHERE condition : AND wp_zensor.moderation_status = 'approved' Could you please show me; where should I add these modification on the category link presentation below: <h2>Politics</h2> <?php $recent = new WP_Query("cat=31&showposts=1"); while($recent->have_posts()) : $recent->the_post();?> <b><a href="<?php the_permalink() ?>" rel="bookmark"><?php the_title(); ?></a></b> <?php the_content_limit(140, "devami &raquo;"); ?> <div class="hppostmeta"> <p><?php the_time('j F Y, H:i'); ?> | <?php the_author_posts_link(); ?></p> </div> <?php endwhile; ?> Or any general solutions will be welcomed. Thanks. BK

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  • How can I find all records for a model without doing a long list of "OR" conditions?

    - by gomezuk
    I'm having trouble composing a CakePHP find() which returns the records I'm looking for. My associations go like this: User -(has many)- Friends , User -(has many)- Posts I'm trying to display a list of all a user's friends recent posts, in other words, list every post that was created by a friend of the current user logged in. The only way I can think of doing this is by putting all the user's friends' user_ids in a big array, and then looping through each one, so that the find() call would look something like: $posts = $this->Post->find('all',array( 'conditions' => array( 'Post.user_id' => array( 'OR' => array( $user_id_array[0],$user_id_array[1],$user_id_array[2] # .. etc ) ) ) )); I get the impression this isn't the best way of doing things as if that user is popular that's a lot of OR conditions. Can anyone suggest a better alternative?

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  • Help with query in Microsoft Access

    - by Gold
    I have 2 tables: Table A: code | name Table B: barcode | name Table B has full barcode and name, Table A has only code. I need to run update query that fill name in Table A. I tried something like: update A set name = (select top 1 Name from B where B.Code = mid(A.Barcode,1,8)) but it doesn't work.

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  • count(*) vs count(column-name) - which is more correct?

    - by bread
    Does it make a difference if you do count(*) vs count(column-name) as in these two examples? I have a tendency to always write count(*) because it seems to fit better in my mind with the notion of it being an aggregate function, if that makes sense. But I'm not sure if it's technically best as I tend to see example code written without the * more often than not. count(*): select customerid, count(*), sum(price) from items_ordered group by customerid having count(*) > 1; vs. count(column-name): SELECT customerid, count(customerid), sum(price) FROM items_ordered GROUP BY customerid HAVING count(customerid) > 1;

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