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  • How can I design my classes for a calendar based on database events?

    - by Gianluca78
    I'm developing a web calendar in php (using Symfony2) inspired by iCal for a project of mine. At this moment, I have two classes: a class "Calendar" and a class "CalendarCell". Here you are the two classes properties and method declarations. class Calendar { private $month; private $monthName; private $year; private $calendarCellList = array(); private $translator; public function __construct($month, $year, $translator) {} public function getCalendarCells() {} public function getMonth() {} public function getMonthName() {} public function getNextMonth() {} public function getNextYear() {} public function getPreviousMonth() {} public function getPreviousYear() {} public function getYear() {} private function calculateDaysPreviousMonth() {} private function calculateNumericDayOfTheFirstDayOfTheWeek() {} private function isCurrentDay(\DateTime $dateTime) {} private function isDifferentMonth(\DateTime $dateTime) {} } class CalendarCell { private $day; private $month; private $dayNameAbbreviation; private $numericDayOfTheWeek; private $isCurrentDay; private $isDifferentMonth; private $translator; public function __construct(array $parameters) {} public function getDay() {} public function getMonth() {} public function getDayNameAbbreviation() {} public function isCurrentDay() {} public function isDifferentMonth() {} } Each calendar day can includes many events stored in a database. My question is: which is the best way to manage these events in my classes? I think to add a eventList property in CalendarCell and populate it with an array of CalendarEvent objects fetched by the database. This kind of solution doesn't allow other coders to reuse the classes without db (because I should inject at least a repository services also) just to create and visualize a calendar... so maybe it could be better to extend CalendarCell (for instance in CalendarCellEvent) and add the database features? I feel like I'm missing some crucial design pattern! Any suggestion will be very appreciated!

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  • PHP Code (modules) included via MySQL database, good idea?

    - by ionFish
    The main script includes "modules" which add functionality to it. Each module is set up like this: <?php //data collection stuff //(...) approx 80 lines of code //end data collection $var1 = 'some data'; $var2 = 'more data'; $var3 = 'other data'; ?> Each module has the same exact variables, just the data collection is different. I was wondering if it's a reasonable idea to store the module data in MySQL like this: [database] |_modules |_name |_function (the raw PHP data from above) |_description |_author |_update-url |_version |_enabled ...and then include the PHP-data from the database and execute it? Something like, a tab-navigation system at the top of the page for each module name, then inside each of those tabs the page content would function by parsing the database-stored code of the module from the function section. The purpose would be to save code space (fewer lines), allow for easy updates, and include/exclude modules based on the enabled option. This is how many other web-apps work, some of my own too. But never had I thought about this so deeply. Are there any drawbacks or security risks to this?

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  • Legit? Two foreign keys referencing the same primary key.

    - by Ryan
    Hi All, I'm a web developer and have recently started a project with a company. Currently, I'm working with their DBA on getting the schema laid out for the site, and we've come to a disagreement regarding the design on a couple tables, and I'd like some opinions on the matter. Basically, we are working on a site that will implement a "friends" network. All users of the site will be contained in a table tblUsers with (PersonID int identity PK, etc). What I am wanting to do is to create a second table, tblNetwork, that will hold all of the relationships between users, with (NetworkID int identity PK, Owners_PersonID int FK, Friends_PersonID int FK, etc). Or conversely, remove the NetworkID, and have both the Owners_PersonID and Friends_PersonID shared as the Primary key. This is where the DBA has his problem. Saying that "he would only implement this kind of architecture in a data warehousing schema, and not for a website, and this is just another example of web developers trying to take the easy way out." Now obviously, his remark was a bit inflammatory, and that have helped motivate me to find an suitable answer, but more so, I'd just like to know how to do it right. I've been developing databases and programming for over 10 years, have worked with some top-notch minds, and have never heard this kind of argument. What the DBA is wanting to do is instead of storing both the Owners_PersonId and Friends_PersonId in the same table, is to create a third table tblFriends to store the Friends_PersonId, and have the tblNetwork have (NetworkID int identity PK, Owner_PersonID int FK, FriendsID int FK(from TBLFriends)). All that tblFriends would house would be (FriendsID int identity PK, Friends_PersonID(related back to Persons)). To me, creating the third table is just excessive in nature, and does nothing but create an alias for the Friends_PersonID, and cause me to have to add (what I view as unneeded) joins to all my queries, not to mention the extra cycles that will be necessary to perform the join on every query. Thanks for reading, appreciate comments. Ryan

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  • What is the proper query to get all the children in a tree?

    - by Nathan Adams
    Lets say I have the following MySQL structure: CREATE TABLE `domains` ( `id` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT, `domain` CHAR(50) NOT NULL, `parent` INT(11) DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=MYISAM AUTO_INCREMENT=10 DEFAULT CHARSET=latin1 insert into `domains`(`id`,`domain`,`parent`) values (1,'.com',0); insert into `domains`(`id`,`domain`,`parent`) values (2,'example.com',1); insert into `domains`(`id`,`domain`,`parent`) values (3,'sub1.example.com',2); insert into `domains`(`id`,`domain`,`parent`) values (4,'sub2.example.com',2); insert into `domains`(`id`,`domain`,`parent`) values (5,'s1.sub1.example.com',3); insert into `domains`(`id`,`domain`,`parent`) values (6,'s2.sub1.example.com',3); insert into `domains`(`id`,`domain`,`parent`) values (7,'sx1.s1.sub1.example.com',5); insert into `domains`(`id`,`domain`,`parent`) values (8,'sx2.s2.sub1.example.com',6); insert into `domains`(`id`,`domain`,`parent`) values (9,'x.sub2.example.com',4); In my mind that is enough to emulate a simple tree structure: .com | example / \ sub1 sub2 ect My problem is that give sub1.example.com I want to know all the children of sub1.example.com without using multiple queries in my code. I have tried joining the table to itself and tried to use subqueries, I can't think of anything that will reveal all the children. At work we are using MPTT to keep in hierarchal order a list of domains/subdomains however, I feel that there is an easier way to do it. I did some digging and someone did something similar but they required the use of a function in MySQL. I don't think for something simple like this we would need a whole function. Maybe I am just dumb and not seeing some sort of obvious solution. Also, feel free to alter the structure.

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  • Can someone describe the nested set model from a C#/LINQ perspective?

    - by Chad
    I know the nested set model doesn't pertain to the C# language or LINQ directly... it's what I'm using to develop my web app. For hierarchical data (categories with sub-categories in my case), I'm currently using something similar to the Adjacency List model. At the moment, I've only got 2 levels of categories, but I'd like to take it further and allow for n levels of categories using the nested set model. I'm not quite clear on how to use it in a C# context. Here's the article I'm reading on the nested set model. Though this article cleared up my confusion some, I still have a big ?? in my head: - Is inserting, updating or deleting categories tedious? It looks like the left and right numbers would require re-numbering... what would the LINQ queries look like for the following scenarios? Delete a child node (re-number all node's left/right values) Delete a parent node (what do you do with the orphans?) Move a child node to a different parent node (renumber again) If my understanding is correct, at all times the child node's left/right values will always be between the parent node's left/right values, am I correct? Seems easy enough, if only the categories were static... most likely I need to spend more time to get my head around the concept. Any help is greatly appreciated!

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  • Use the repository pattern when using PLINQO generated data?

    - by Chad
    I'm "upgrading" an MVC app. Previously, the DAL was a part of the Model, as a series of repositories (based on the entity name) using standard LINQ to SQL queries. Now, it's a separate project and is generated using PLINQO. Since PLINQO generates query extensions based on the properties of the entity, I started using them directly in my controller... and eliminated the repositories all together. It's working fine, this is more a question to draw upon your experience, should I continue down this path or should I rebuild the repositories (using PLINQO as the DAL within the repository files)? One benefit of just using the PLINQO generated data context is that when I need DB access, I just make one reference to the the data context. Under the repository pattern, I had to reference each repository when I needed data access, sometimes needing to reference multiple repositories on a single controller. The big benefit I saw on the repositories, were aptly named query methods (i.e. FindAllProductsByCategoryId(int id), etc...). With the PLINQO code, it's _db.Product.ByCatId(int id) - which isn't too bad either. I like both, but where it gets "harrier" is when the query uses predicates. I can roll that up into the repository query method. But on the PLINQO code, it would be something like _db.Product.Where(x = x.CatId == 1 && x.OrderId == 1); I'm not so sure I like having code like that in my controllers. Whats your take on this?

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  • MySql Query lag time / deadlock?

    - by Click Upvote
    When there are multiple PHP scripts running in parallel, each making an UPDATE query to the same record in the same table repeatedly, is it possible for there to be a 'lag time' before the table is updated with each query? I have basically 5-6 instances of a PHP script running in parallel, having been launched via cron. Each script gets all the records in the items table, and then loops through them and processes them. However, to avoid processing the same item more than once, I store the id of the last item being processed in a seperate table. So this is how my code works: function getCurrentItem() { $sql = "SELECT currentItemId from settings"; $result = $this->db->query($sql); return $result->get('currentItemId'); } function setCurrentItem($id) { $sql = "UPDATE settings SET currentItemId='$id'"; $this->db->query($sql); } $currentItem = $this->getCurrentItem(); $sql = "SELECT * FROM items WHERE status='pending' AND id > $currentItem'"; $result = $this->db->query($sql); $items = $result->getAll(); foreach ($items as $i) { //Check if $i has been processed by a different instance of the script, and if so, //leave it untouched. if ($this->getCurrentItem() > $i->id) continue; $this->setCurrentItem($i->id); // Process the item here } But despite of all the precautions, most items are being processed more than once. Which makes me think that there is some lag time between the update queries being run by the PHP script, and when the database actually updates the record. Is it true? And if so, what other mechanism should I use to ensure that the PHP scripts always get only the latest currentItemId even when there are multiple scripts running in parrallel? Would using a text file instead of the db help?

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  • How to combine a Distance and Keyword SQL query?

    - by Jason
    Hi Folks, I have a tables in my database called "points" and "category". A user will input info into both a location input and a keyword input text box. Then I want to find points in my table where the keyword matches either the "title" field in the points table, or the "category" but are within a certain distance from the user's location. I want to order the results by distance. Here are the 2 queries which btoh work independently: $mysql = "SELECT *, ( 3959 * acos( cos( radians('$search_lat') ) * cos( radians( lat ) ) * cos( radians( longi ) - radians('$search_lng') ) + sin( radians('$search_lat') ) * sin( radians( lat ) ) ) ) AS distance FROM points HAVING distance < '$radius'"; $mysql2 = "SELECT * FROM `points` LEFT JOIN category USING ( category_id ) WHERE (point_title LIKE '%$esc_catsearch%' OR category.title LIKE '%$esc_catsearch%')"; Here is what I tried: $sql_search = sprintf("SELECT *,point_id FROM points WHERE point_title LIKE '%%%s%%' UNION SELECT *, ( 3959 * acos( cos( radians('%s') ) * cos( radians( lat ) ) * cos( radians( longi ) - radians('%s') ) + sin( radians('%s') ) * sin( radians( lat ) ) ) ) AS distance FROM points HAVING distance < '%s' ORDER BY distance LIMIT %d , %d", $esc_catsearch, mysql_real_escape_string($search_lat), mysql_real_escape_string($search_lng), mysql_real_escape_string($search_lat), mysql_real_escape_string($radius), $offset, $rowsPerPage); But it tells me there is no know column "distance". If I remove the "Order By" phrase then it works but I'm still not sure this is giving me the results I want. I also tried the query the other way around with the distance search first but that seems to ignore my keyword. Any thoughts would be much appreciated!

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  • Java MySQL Query Problem MySQLSyntaxErrorException When Creating a Table

    - by Aqib Mushtaq
    I fairly new to MySQL with Java, but I have executed a few successful INSERT queries however cannot seem to get the CREATE TABLE query to execute without getting the 'MySQLSyntaxErrorException' exception. My code is as follows: import java.sql.*; Statement stmt; Class.forName("com.mysql.jdbc.Driver"); String url = "jdbc:mysql://localhost:3306/mysql"; Connection con = DriverManager.getConnection(url, "root", "password"); stmt = con.createStatement(); String tblSQL = "CREATE TABLE IF NOT EXISTS \'dev\'.\'testTable\' (\n" + " \'id\' int(11) NOT NULL AUTO_INCREMENT,\n" + " \'date\' smallint(6) NOT NULL\n" + ") ENGINE=MyISAM DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;"; stmt.executeUpdate(tblSQL); stmt.close(); con.close(); And the error is as follows: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''dev'.'testTable' ( 'id' int(11) NOT NULL AUTO_INCREMENT, 'date' smallint(6) N' at line 1 I would appreciate it if anyone could spot the mistake in this query, as I've tried executing this within phpMyAdmin and it works as it should. Thanks in advance.

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  • Combining cache methods - memcache/disk based

    - by Industrial
    Hi! Here's the deal. We would have taken the complete static html road to solve performance issues, but since the site will be partially dynamic, this won't work out for us. What we have thought of instead is using memcache + eAccelerator to speed up PHP and take care of caching for the most used data. Here's our two approaches that we have thought of right now: Using memcache on all<< major queries and leaving it alone to do what it does best. Usinc memcache for most commonly retrieved data, and combining with a standard harddrive-stored cache for further usage. The major advantage of only using memcache is of course the performance, but as users increases, the memory usage gets heavy. Combining the two sounds like a more natural approach to us, even though the theoretical compromize in performance. Memcached appears to have some replication features available as well, which may come handy when it's time to increase the nodes. What approach should we use? - Is it stupid to compromize and combine the two methods? Should we insted be focusing on utilizing memcache and instead focusing on upgrading the memory as the load increases with the number of users? Thanks a lot!

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  • Using memory-based cache together with conventional cache

    - by Industrial
    Hi! Here's the deal. We would have taken the complete static html road to solve performance issues, but since the site will be partially dynamic, this won't work out for us. What we have thought of instead is using memcache + eAccelerator to speed up PHP and take care of caching for the most used data. Here's our two approaches that we have thought of right now: Using memcache on all<< major queries and leaving it alone to do what it does best. Usinc memcache for most commonly retrieved data, and combining with a standard harddrive-stored cache for further usage. The major advantage of only using memcache is of course the performance, but as users increases, the memory usage gets heavy. Combining the two sounds like a more natural approach to us, even though the theoretical compromize in performance. Memcached appears to have some replication features available as well, which may come handy when it's time to increase the nodes. What approach should we use? - Is it stupid to compromize and combine the two methods? Should we insted be focusing on utilizing memcache and instead focusing on upgrading the memory as the load increases with the number of users? Thanks a lot!

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  • MySql Query lag time?

    - by Click Upvote
    When there are multiple PHP scripts running in parallel, each making an UPDATE query to the same record in the same table repeatedly, is it possible for there to be a 'lag time' before the table is updated with each query? I have basically 5-6 instances of a PHP script running in parallel, having been launched via cron. Each script gets all the records in the items table, and then loops through them and processes them. However, to avoid processing the same item more than once, I store the id of the last item being processed in a seperate table. So this is how my code works: function getCurrentItem() { $sql = "SELECT currentItemId from settings"; $result = $this->db->query($sql); return $result->get('currentItemId'); } function setCurrentItem($id) { $sql = "UPDATE settings SET currentItemId='$id'"; $this->db->query($sql); } $currentItem = $this->getCurrentItem(); $sql = "SELECT * FROM items WHERE status='pending' AND id > $currentItem'"; $result = $this->db->query($sql); $items = $result->getAll(); foreach ($items as $i) { //Check if $i has been processed by a different instance of the script, and if so, //leave it untouched. if ($this->getCurrentItem() > $i->id) continue; $this->setCurrentItem($i->id); // Process the item here } But despite of all the precautions, most items are being processed more than once. Which makes me think that there is some lag time between the update queries being run by the PHP script, and when the database actually updates the record. Is it true? And if so, what other mechanism should I use to ensure that the PHP scripts always get only the latest currentItemId even when there are multiple scripts running in parrallel? Would using a text file instead of the db help?

    Read the article

  • Using memcache together with conventional cache

    - by Industrial
    Hi! Here's the deal. We would have taken the complete static html road to solve performance issues, but since the site will be partially dynamic, this won't work out for us. What we have thought of instead is using memcache + eAccelerator to speed up PHP and take care of caching for the most used data. Here's our two approaches that we have thought of right now: Using memcache on all<< major queries and leaving it alone to do what it does best. Usinc memcache for most commonly retrieved data, and combining with a standard harddrive-stored cache for further usage. The major advantage of only using memcache is of course the performance, but as users increases, the memory usage gets heavy. Combining the two sounds like a more natural approach to us, even though the theoretical compromize in performance. Memcached appears to have some replication features available as well, which may come handy when it's time to increase the nodes. What approach should we use? - Is it stupid to compromize and combine the two methods? Should we insted be focusing on utilizing memcache and instead focusing on upgrading the memory as the load increases with the number of users? Thanks a lot!

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  • Using Memcached in Python/Django - questions.

    - by Thomas
    I am starting use Memcached to make my website faster. For constant data in my database I use this: from django.core.cache import cache cache_key = 'regions' regions = cache.get(cache_key) if result is None: """Not Found in Cache""" regions = Regions.objects.all() cache.set(cache_key, regions, 2592000) #(2592000sekund = 30 dni) return regions For seldom changed data I use signals: from django.core.cache import cache from django.db.models import signals def nuke_social_network_cache(self, instance, **kwargs): cache_key = 'networks_for_%s' % (self.instance.user_id,) cache.delete(cache_key) signals.post_save.connect(nuke_social_network_cache, sender=SocialNetworkProfile) signals.post_delete.connect(nuke_social_network_cache, sender=SocialNetworkProfile) Is it correct way? I installed django-memcached-0.1.2, which show me: Memcached Server Stats Server Keys Hits Gets Hit_Rate Traffic_In Traffic_Out Usage Uptime 127.0.0.1 15 220 276 79% 83.1 KB 364.1 KB 18.4 KB 22:21:25 Can sombody explain what columns means? And last question. I have templates where I am getting much records from a few table (relationships). So in my view I get records from one table and in templates show it and related info from others. Generating page last a few seconds for very small table (<100records). Is it some easy way to cache queries from templates? Have I to do some big structure in my view (with all related tables), cache it and send to template?

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  • Most watched videos this week

    - by Jan Hancic
    I have a youtube like web-page where users upload&watch videos. I would like to add a "most watched videos this week" list of videos to my page. But this list should not contain just the videos that ware uploaded in the previous week, but all videos. I'm currently recording views in a column, so I have no information on when a video was watched. So now I'm searching for a solution to how to record this data. The first is the most obvious (and the correct one, as far as I know): have a separate table in which you insert a new line every time you want to record a new view (storing the ID of the video and the timestamp). I'm worried that I would quickly get huge amounts of data in this table, and queries using this table would be extremely slow (we get about 3 million views a month). The second solution isn't as flexible but is more easy on the database. I would add 7 columns to the "videos" table (one for each day of the week): views_monday, views_tuesday , views_wednesday, ... And increment the value in the correct column based on the day it is. And I would reset the current day's column to 0 at midnight. I could then easily get the most watched videos of the week by summing this 7 columns. What do you think, should I bother with the first solution or will the second one suffice for my case? If you have a better solution please share! Oh, I'm using MySQL.

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  • I have data about deadlocks, but I can't understand why they occur

    - by Alex
    I am receiving a lot of deadlocks in my big web application. http://stackoverflow.com/questions/2941233/how-to-automatically-re-run-deadlocked-transaction-asp-net-mvc-sql-server Here I wanted to re-run deadlocked transactions, but I was told to get rid of the deadlocks - it's much better, than trying to catch the deadlocks. So I spent the whole day with SQL Profiler, setting the tracing keys etc. And this is what I got. There's a Users table. I have a very high usable page with the following query (it's not the only query, but it's the one that causes troubles) UPDATE Users SET views = views + 1 WHERE ID IN (SELECT AuthorID FROM Articles WHERE ArticleID = @ArticleID) And then there's the following query in ALL pages: User = DB.Users.SingleOrDefault(u => u.Password == password && u.Name == username); That's where I get User from cookies. Very often a deadlock occurs and this second Linq-to-SQL query is chosen as a victim, so it's not run, and users of my site see an error screen. I read a lot about deadlocks... And I don't understand why this is causing a deadlock. So obviously both of this queries run very often. At least once a second. Maybe even more often (300-400 users online). So they can be run at the same time very easily, but why does it cause a deadlock? Please help. Thank you

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  • Get the first and last posts in a thread

    - by Grampa
    I am trying to code a forum website and I want to display a list of threads. Each thread should be accompanied by info about the first post (the "head" of the thread) as well as the last. My current database structure is the following: threads table: id - int, PK, not NULL, auto-increment name - varchar(255) posts table: id - int, PK, not NULL, auto-increment thread_id - FK for threads The tables have other fields as well, but they are not relevant for the query. I am interested in querying threads and somehow JOINing with posts so that I obtain both the first and last post for each thread in a single query (with no subqueries). So far I am able to do it using multiple queries, and I have defined the first post as being: SELECT * FROM threads t LEFT JOIN posts p ON t.id = p.thread_id ORDER BY p.id LIMIT 0, 1 The last post is pretty much the same except for ORDER BY id DESC. Now, I could select multiple threads with their first or last posts, by doing: SELECT * FROM threads t LEFT JOIN posts p ON t.id = p.thread_id ORDER BY p.id GROUP BY t.id But of course I can't get both at once, since I would need to sort both ASC and DESC at the same time. What is the solution here? Is it even possible to use a single query? Is there any way I could change the structure of my tables to facilitate this? If this is not doable, then what tips could you give me to improve the query performance in this particular situation?

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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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  • MySQL query problem

    - by Luke
    Ok, I have the following problem. I have two InnoDB tables: 'places' and 'events'. One place can have many events, but event can be created without entering place. In this case event's foreign key is NULL. Simplified structure of the tables looks as follows: CREATE TABLE IF NOT EXISTS `events` ( `id` int(11) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(255) COLLATE utf8_bin NOT NULL, `places_id` int(9) unsigned DEFAULT NULL, PRIMARY KEY (`id`), KEY `fk_events_places` (`places_id`), ) ENGINE=InnoDB; ALTER TABLE `events` ADD CONSTRAINT `events_ibfk_1` FOREIGN KEY (`places_id`) REFERENCES `places` (`id`) ON DELETE CASCADE ON UPDATE NO ACTION; CREATE TABLE IF NOT EXISTS `places` ( `id` int(9) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(255) COLLATE utf8_bin NOT NULL, PRIMARY KEY (`id`), ) ENGINE=InnoDB; Question is, how to construct query which contains name of the event and name of the corresponding place (or no value, in case there is no place assigned?). I am able to do it with two queries, but then I am visibly separating events which have place assigned from the ones that are without place. Help really appreciated.

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  • Many tables for many users?

    - by Seagull
    I am new to web programming, so excuse the ignorance... ;-) I have a web application that in many ways can be considered to be a multi-tenant environment. By this I mean that each user of the application gets their own 'custom' environment, with absolutely no interaction between those users. So far I have built the web application as a 'single user' environment. In other words, I haven't actually done anything to support multi-users, but only worked on the functionality I want from the app. Here is my problem... What's the best way to build a multi-user environment: All users point to the same 'core' backend. In other words, I build the logic to separate users via appropriate SQL queries (eg. select * from table where user='123' and attribute='456'). Each user points to a unique tablespace, which is built separately as they join the system. In this case I would simply generate ALL the relevant SQL tables per user, with some sort of suffix for the user. (eg. now a query would look like 'select * from table_ where attribute ='456'). In short, it's a difference between "select * from table where USER=" and "select * from table_USER".

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  • help with delete where not in query

    - by kralco626
    I have a lookup table (##lookup). I know it's bad design because I'm duplicating data, but it speeds up my queries tremendously. I have a query that populates this table insert into ##lookup select distinct col1,col2,... from table1...join...etc... I would like to simulate this behavior: delete from ##lookup insert into ##lookup select distinct col1,col2,... from table1...join...etc... This would clearly update the table correctly. But this is a lot of inserting and deleting. It messes with my indexes and locks up the table for selecting from. This table could also be updated by something like: delete from ##lookup where not in (select distinct col1,col2,... from table1...join...etc...) insert into ##lookup (select distinct col1,col2,... from table1...join...etc...) except if it is already in the table The second way may take longer, but I can say "with no lock" and I will be able to select from the table. Any ideas on how to write the query the second way?

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  • How should I solve this MySql problem (PHP) ? (Beginner)

    - by Camran
    I have several tables in a MySql database. I have a classifieds website, and at the bottom I display the users last visited classifieds. I do this by storing the ID:s of the ads to an array in the cookie. Now, my db is made up like this kindof: Main Table: // Stores global information, ie these fields have to be filled out in every record, never be blank ID Price category Seller Item Table: // Stores descriptive info about whats for sale ID AD_ID (FK) //This is the same as ID in the MAIN TABLE Color Size Mileage etc My problem is that I need to know what category the ad is in, in order to query mysql for the right information I think. So I need two variables, but the cookie only has one (ID) stored. Offcourse I could make two queries, first one just matching the ID to the main_table and fetch the category from the Main_table. Then make the second query and fetch all other info from the right table. Here is an example if the category was Vehicles: SELECT * FROM main_table, vehicles_table, WHERE main_table.id=$id_from_cookie AND main_table.ad_id=vehicles_table.ad_id As you can see above, I need the category to write in what table to check, right? But I think there must be a smarter way, like fetching them in one single query using only one variable (id from cookie)? How should I do this? Understand? Let me know if you need more input... Thanks

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  • Pay online service

    - by Samuel
    Hellow, I have a database where you can select articles etc, users have an account, it's all in mysql and php (i guess you don't need that code). What i was wondering was how to write a script that allows users to pay online for the articles they selected? It doesn't need to be any code, just ideas / hints / tips / ... (that are doable in PHP or something similar) Thanks in advance!! -Samuel

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  • "Create table if not exists" - how to check the schema, too?

    - by Joonas Pulakka
    Is there a (more or less) standard way to check not only whether a table named mytable exists, but also whether its schema is similar to what it should be? I'm experimenting with H2 database, and CREATE TABLE IF NOT EXISTS mytable (....) statements apparently only check for the table´s name. I would expect to get an exception if there's a table with the given name, but different schema.

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