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  • Should I Split Tables Relevant to X Module Into Different DB? Mysql

    - by Michael Robinson
    I've inherited a rather large and somewhat messy codebase, and have been tasked with making it faster, less noodly and generally better. Currently we use one big database to hold all data for all aspects of the site. As we need to plan for significant growth in the future, I'm considering splitting tables relevant to specific sections of the site into different databases, so if/when one gets too large for one server I can more easily migrate some user data to different mysql servers while retaining overall integrity. I would still need to use joins on some tables across the new databases. Is this a normal thing to do? Would I incur a performance hit because of this?

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  • How should I build a simple database package for my python application?

    - by Carson Myers
    I'm building a database library for my application using sqlite3 as the base. I want to structure it like so: db/ __init__.py users.py blah.py etc.py So I would do this in Python: import db db.users.create('username', 'password') I'm suffering analysis paralysis (oh no!) about how to handle the database connection. I don't really want to use classes in these modules, it doesn't really seem appropriate to be able to create a bunch of "users" objects that can all manipulate the same database in the same ways -- so inheriting a connection is a no-go. Should I have one global connection to the database that all the modules use, and then put this in each module: #users.py from db_stuff import connection Or should I create a new connection for each module and keep that alive? Or should I create a new connection for every transaction? How are these database connections supposed to be used? The same goes for cursor objects: Do I create a new cursor for each transaction? Create just one for each database connection?

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  • All connections in pool are in use

    - by veljkoz
    We currently have a little situation on our hands - it seems that someone, somewhere forgot to close the connection in code. Result is that the pool of connections is relatively quickly exhausted. As a temporary patch we added Max Pool Size = 500; to our connection string on web service, and recycle pool when all connections are spent, until we figure this out. So far we have done this: SELECT SPId FROM MASTER..SysProcesses WHERE DBId = DB_ID('MyDb') and last_batch < DATEADD(MINUTE, -15, GETDATE()) to get SPID's that aren't used for 15 minutes. We're now trying to get the query that was executed last using that SPID with: DBCC INPUTBUFFER(61) but the queries displayed are various, meaning either something on base level regarding connection manipulation was broken, or our deduction is erroneous... Is there an error in our thinking here? Does the DBCC / sysprocesses give results we're expecting or is there some side-effect catch? (for example, connections in pool influence?) (please, stick to what we could find out using SQL since the guys that did the code are many and not all present right now)

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  • How to find foreign-key dependencies pointing to one record in Oracle?

    - by daveslab
    Hi folks, I have a very large Oracle database, with many many tables and millions of rows. I need to delete one of them, but want to make sure that dropping it will not break any other dependent rows that point to it as a foreign key record. Is there a way to get a list of all the other records, or at least table schemas, that point to this row? I know that I could just try to delete it myself, and catch the exception, but I won't be running the script myself and need it to run clean the first time through. I have the tools SQL Developer from Oracle, and PL/SQL Developer from AllRoundAutomations at my disposal. Thanks in advance!

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  • mysql query trying to search by alias involving CASES and aggregate functions UGH!

    - by dqhendricks
    I have two tables left joined. The query is grouped by the left table's ID column. The right table has a date column called close_date. The problem is, if there are any right table records that have not been closed (thus having a close_date of 0000-00-00), then I do not want any of the left table records to be shown, and if there are NO right table records with a close_date of 0000-00-00, I would like only the right table record with the MAX close date to be returned. So for simplicity sake, let's say the tables look like this: Table1 id 1 2 Table2 table1_id | close_date 1 | 0000-00-00 1 | 2010-01-01 2 | 2010-01-01 2 | 2010-01-02 I would like the query to only return this: Table1.id | Table2.close_date 2 | 2010-01-02 I tried to come up with an answer using aliased CASES and aggregate functions, but I could not search by the result, and I was attempting not to make a 3 mile long query to solve the problem. I looked through a few of the related posts on here, but none seem to meet the criteria of this particular case. Any pushes in the right direction would be greatly appreciated. Thanks!

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  • Options for storing large text blobs in/with an SQL database?

    - by kdt
    Hi, I have some large volumes of text (log files) which may be very large (up to gigabytes). They are associated with entities which I'm storing in a database, and I'm trying to figure out whether I should store them within the SQL database, or in external files. It seems like in-database storage may be limited to 4GB for LONGTEXT fields in MySQL, and presumably other DBs have similar limits. Also, storing in the database presumably precludes any kind of seeking when viewing this data -- I'd have to load the full length of the data to render any part of it, right? So it seems like I'm leaning towards storing this data out-of-DB: are my misgivings about storing large blobs in the database valid, and if I'm going to store them out of the database then are there any frameworks/libraries to help with that? (I'm working in python but am interested in technologies in other languages too)

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  • Postgresql Output column from another table

    - by muffin
    i'm using Postgresql, my question is specifically about querying from a table that's in another table and i'm really having trouble with this one. In fact, i'm absolutely mentally blocked. I'll try to define the relations of the tables as much as I can. I have a table entry which is like this: Each of the entries has a group_id; when they are 'advanced' to the next stage, the old entries are marked is_active = false, and a new assignment is done, so C & D are advanced stages of A & B. I have another table (which acts as a record keeper) , in which the storage_log_id refers to, this is the storage_log table : But then I have another table, to really find out where the entries are actually stored - storage table : To define my problem properly. Each entry has a storage_log_id (but some doesn't have yet), and a storage_log has a storage_id to refer to the actual table and find the storage label. The sql query i'm trying to do should output this one: Where The actual storage label is shown instead of the log id. This is so far what i've done: select e.id, e.group_id, e.name, e.stage, s.label from operational.entry e, operational.storage_log sl, operational.storage s where e.storage_log_id = sl.id and sl.storage_id = s.id But this just returns 3 rows, showing only the ones that have the seed_storage_log_id set; I should be able to see even those without logs, and especially the active ones. adding e.is_active = true to the condition makes the results empty. So, yeah i'm stuck. Need help, Thanks guys!

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  • how to design a db like Facebook where users can update their status and of the fb page as admin

    - by Harsha M V
    i am designing a database where users can update status messages of theirs and they can create pages groups like facebook fan page and post status like the admin of the page and not as a user. user(id, name..) group(id, name...) group_admin(group_id, user_id) this is my set up. Is this the way to do it. How to post under the group as an admin. will i need to make a check to every user if he is the admin or not ?

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  • Three customer addresses in one table or in separate tables?

    - by DR
    In my application I have a Customer class and an Address class. The Customer class has three instances of the Address class: customerAddress, deliveryAddress, invoiceAddress. Whats the best way to reflect this structure in a database? The straightforward way would be a customer table and a separate address table. A more denormalized way would be just a customer table with columns for every address (Example for "street": customer_street, delivery_street, invoice_street) What are your experiences with that? Are there any advantages and disadvantages of these approaches?

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  • SQL SERVER – Generate Report for Index Physical Statistics – SSMS

    - by pinaldave
    Few days ago, I wrote about SQL SERVER – Out of the Box – Activity and Performance Reports from SSSMS (Link). A user asked me a question regarding if we can use similar reports to get the detail about Indexes. Yes, it is possible to do the same. There are similar type of reports are available at Database level, just like those available at the Server Instance level. You can right click on Database name and click Reports. Under Standard Reports, you will find following reports. Disk Usage Disk Usage by Top Tables Disk Usage by Table Disk Usage by Partition Backup and Restore Events All Transactions All Blocking Transactions Top Transactions by Age Top Transactions by Blocked Transactions Count Top Transactions by Locks Count Resource Locking Statistics by Objects Object Execute Statistics Database Consistency history Index Usage Statistics Index Physical Statistics Schema Change history User Statistics Select the Reports with name Index Physical Statistics. Once click, a report containing all the index names along with other information related to index will be visible, e.g. Index Type and number of partitions. One column that caught my interest was Operation Recommended. In some place, it suggested that index needs to be rebuilt. It is also possible to click and expand the column of partitions and see additional details about index as well. DBA and Developers who just want to have idea about how your index is and its physical statistics can use this tool. Click to Enlarge Note: Please note that I will rebuild my indexes just because this report is recommending it. There are many other parameters you need to consider before rebuilding indexes. However, this tool gives you the accurate stats of your index and it can be right away exported to Excel or PDF writing by clicking on the report. Reference : Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, SQL, SQL Authority, SQL Index, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Server Management Studio, SQL Tips and Tricks, SQL Utility, T SQL, Technology

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  • SQLAuthority News – Community Tech Days – December 11, 2010

    - by pinaldave
    Community Tech Days are very close on December 11. The venue details are as following: H K Hall, H K College Campus, Near Handloom House, Opp. Natraj Cinema, Ashram Road, Ahmedabad – 380009 Click here to Registration for the event. Please read the announcement details here. I will be speaking on following session. Best Database Practice for SharePoint Server This session will be very unique. I will be starting with a bit pessimistic talk about how one cannot many things in SQL Server when SharePoint Server is installed. I will go over in the details for the reasons for the same. Right after this 5 minutes I am going to show few things to attendees which they can apply right away to their database and instantly get the performance. I am going to share the easy scripts with them online right away and if they run the same on their SharePoint Database, they will get the performance right out of the box right away – I Promise! This is the same session I presented at SharePoint Conference and I have received excellent feedback on the same subject. Join us! Reference: Pinal Dave (http://blog.SQLAuthority.com)   Filed under: MVP, Pinal Dave, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, SQLAuthority News, T SQL, Technology

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  • SQL Contest – Win 10 Amazon Gift Cards worth (USD 200) and 10 NuoDB T-Shirts

    - by Pinal Dave
    This month, we have yet not run any contest so we will be running a very interesting contest with the help of good guys at NuoDB. NuoDB has just released version 2.0 and You can download NuoDB from here. NuoDB’s NewSQL distributed database is designed to be a single database that works across multiple servers, which can scale easily, and scale on demand. That’s one system that gives high connectivity but no latency, complexity or maintenance issues. MySQL works in some circumstances, but a period of growth isn’t one of them. So as a company moves forward, the MySQL database can’t keep pace. Data storage and data replication errors creep in. Soon the diaspora of the offices becomes a problem. Your telephone system isn’t just distributed, it is literally all over the place. You can read my detailed article about how Why VoIP Service Providers Should Think About NuoDB’s Geo Distribution. Here is the contest: Contest Part 1: NuoDB R2.0 delivered a long list of improvements and new features. List three of the major features of NuoDB 2.0. Here is the hint1, hint2, hint3. Contest Part 2: Download NuoDB using this link. Once you download NuoDB, leave a comment over here with the name of the platform and installer size. (For example Windows Platform Size abc.dd MB) Here is the what you can win! Giveaways 10 Amazon Gift Card (Each of USD 20 – total USD 200) 10 Amazingly looking NuoDB T-Shirts (For the first 10 downloads) Rules Participate before Oct 28, 2013. All the valid answers will be published after Oct 28, 2013 and winners will receive an email on Nov 1st, 2013. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL Tagged: NuoDB

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  • SQL SERVER – Download Microsoft SQL Server Compact 4.0 SP1

    - by pinaldave
    Microsoft SQL Server Compact 4.0 is a free, embedded database that software developers can use for building ASP.NET websites and Windows desktop applications. SQL Server Compact 4.0 is the default database for Microsoft WebMatrix. For enhanced development and debugging capabilities, including designer support, Visual Studio can be used to develop ASP.NET web applications and websites using SQL Server Compact 4.0. Enabled to work in the medium or partial trust environments in the web servers, and can be easily deployed along with the website to the third party website hosting service providers. SQL Server CE 4.0 also provides stronger data security with the use of the SHA2 encryption algorithms for encrypting the databases. Latest version also supports T-SQL syntax enhancement by adding support for OFFSET and FETCH that can be used to write paging queries. Used with ADO.NET Entity Framework, SQL Server Compact now supports the columns that have server generated keys like identity, rowguid etc. and the code-first programming model. SQL Server Compact 4.0 is freely redistributable under a redistribution license agreement. SQL Server Compact 3.5 and SQL Server Compact 4.0 can be installed and work side by side on a desktop. Download Microsoft SQL Server Compact 4.0 SP1 Here are my earlier article on SQL Server CE Difference Between SQL Server Compact Edition (CE) and SQL Server Express Edition SQL SERVER – CE – 3 Links to Performance Tuning Compact Edition SQL SERVER – CE – List of Information_Schema System Tables SQL SERVER – Server Side Paging in SQL Server CE (Compact Edition) SQL SERVER – CE – Samples Database for SQL CE 4.0 Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Download, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology

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  • How the "migrations" approach makes database continuous integration possible

    - by David Atkinson
    Testing a database upgrade script as part of a continuous integration process will only work if there is an easy way to automate the generation of the upgrade scripts. There are two common approaches to managing upgrade scripts. The first is to maintain a set of scripts as-you-go-along. Many SQL developers I've encountered will store these in a folder prefixed numerically to ensure they are ordered as they are intended to be run. Occasionally there is an accompanying document or a batch file that ensures that the scripts are run in the defined order. Writing these scripts during the course of development requires discipline. It's all too easy to load up the table designer and to make a change directly to the development database, rather than to save off the ALTER statement that is required when the same change is made to production. This discipline can add considerable overhead to the development process. However, come the end of the project, everything is ready for final testing and deployment. The second development paradigm is to not do the above. Changes are made to the development database without considering the incremental update scripts required to effect the changes. At the end of the project, the SQL developer or DBA, is tasked to work out what changes have been made, and to hand-craft the upgrade scripts retrospectively. The end of the project is the wrong time to be doing this, as the pressure is mounting to ship the product. And where data deployment is involved, it is prudent not to feel rushed. Schema comparison tools such as SQL Compare have made this latter technique more bearable. These tools work by analyzing the before and after states of a database schema, and calculating the SQL required to transition the database. Problem solved? Not entirely. Schema comparison tools are huge time savers, but they have their limitations. There are certain changes that can be made to a database that can't be determined purely from observing the static schema states. If a column is split, how do we determine the algorithm required to copy the data into the new columns? If a NOT NULL column is added without a default, how do we populate the new field for existing records in the target? If we rename a table, how do we know we've done a rename, as we could equally have dropped a table and created a new one? All the above are examples of situations where developer intent is required to supplement the script generation engine. SQL Source Control 3 and SQL Compare 10 introduced a new feature, migration scripts, allowing developers to add custom scripts to replace the default script generation behavior. These scripts are committed to source control alongside the schema changes, and are associated with one or more changesets. Before this capability was introduced, any schema change that required additional developer intent would break any attempt at auto-generation of the upgrade script, rendering deployment testing as part of continuous integration useless. SQL Compare will now generate upgrade scripts not only using its diffing engine, but also using the knowledge supplied by developers in the guise of migration scripts. In future posts I will describe the necessary command line syntax to leverage this feature as part of an automated build process such as continuous integration.

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  • SQLAuthority News – Presented Technical Session at DevReach 2013, Sofia, Bulgaria – Oct 1, 2013

    - by Pinal Dave
    Earlier this month, I had a fantastic time presenting at DevReach 2013, in Sofia, Bulgaria on Oct 1, 2013. DevReach strives to be the premier developer conference in Central and Eastern Europe. It is organized annually in Sofia, Bulgaria. The 8th edition of the conference is moving to a new and bigger venue: Sofia Event Center. In my career, I have presented over 9 different countries (India, USA, Canada, Singapore, Hong Kong, Malaysia, Sri Lanka, Nepal, Thailand), this was the first time for me to present in Europe. DevReach was perfect places to start my journey in Europe as an evangelist. The event was one of the most organized event I have ever come across in my life. The DevRech organization team had perfected every minute detail of the event to perfection. After the event was over I had the opportunity to see Sofia for one day. I presented with one of my most favorite Database Worst Practices Session. Pinal presenting at DevReach 2013, Sofia, Bulgaria DevReach 2013 DevReach 2013 DevReach 2013 Pinal presenting at DevReach 2013, Sofia, Bulgaria Pinal presenting at DevReach 2013, Sofia, Bulgaria Pinal Dave and Stephen Forte at Pluralsight Booth at DevReach 2013, Sofia, Bulgaria Pinal on City Tour of Sofia, Bulgaria Pinal on City Tour of Sofia, Bulgaria Pinal on City Tour of Sofia, Bulgaria Pinal on City Tour of Sofia, Bulgaria Pinal on City Tour of Sofia, Bulgaria Session Title: Secrets of SQL Server: Database Worst Practices Abstract: “Oh my God! What did I do?” Chances are you have heard, or even uttered, this expression. This demo-oriented session will show many examples where database professionals were dumbfounded by their own mistakes, and could even bring back memories of your own early DBA days. The goal of this session is to expose the small details that can be dangerous to the production environment and SQL Server as a whole, as well as talk about worst practices and how to avoid them. Shedding light on some of these perils and the tricks to avoid them may even save your current job. Thanks to Team Telerik for making this one of the best event in my life. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: About Me, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, SQLAuthority Author Visit, T SQL

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  • How do I make complex SQL queries easier to write?

    - by DragonLord
    I'm finding it very difficult to write complex SQL queries involving joins across many (at least 3-4) tables and involving several nested conditions. The queries I'm being asked to write are easily described by a few sentences, but can require a deceptive amount of code to complete. I'm finding myself often using temporary views to write these queries, which seem like a bit of a crutch. What tips can you provide that I can use to make these complex queries easier? More specifically, how do I break these queries down into the steps I need to use to actually write the SQL code? Note that I'm the SQL I'm being asked to write is part of homework assignments for a database course, so I don't want software that will do the work for me. I want to actually understand the code I'm writing. More technical details: The database is hosted on a PostgreSQL server running on the local machine. The database is very small: there are no more than seven tables and the largest table has less than about 50 rows. The SQL queries are being passed unchanged to the server, via LibreOffice Base.

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  • SQLAuthority News – Deployment guide for Microsoft SharePoint Foundation 2010

    - by pinaldave
    SharePoint and SQL Server both goes together – hands to hand. SharePoint installation is very interesting. At various organizations, the installation is very different and have various needs. SQL Server installation with SharePoint is equally important and I have often seen that it is being neglected. Microsoft has published the Deployment Guide for SharePoint Foundation. It talks about various database aspects as well. For optimal sharepoint installation the required version of SQL Server, including service packs and cumulative updates must be installed on the database server. The installation must include any additional features, such as SQL Analysis Services, and the appropriate SharePoint Foundation logins have to be added and configured. The database server must be hardened and, if it is required, databases must be created by the DBA. For more information, see: Hardware and software requirements (SharePoint Foundation 2010) Harden SQL Server for SharePoint environments (SharePoint Foundation 2010) Deploy by using DBA-created databases (SharePoint Foundation 2010) Deployment guide for Microsoft SharePoint Foundation 2010 Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: SharePoint

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  • SQLAuthority News – NuoDB MeetUp on Nov 8, 2012 in Seattle

    - by pinaldave
    I am pleased to let you know that I will be attending again this year’s SQLPASS conference in Seattle and look forward to meeting all of you while at the conference. In the next two weeks, I will provide you with a full agenda of where I will be during PASS. During the week, I will also be stopping by at the NuoDB MeetUp, which will be held close by at the Edge Grill at 1522 6th Ave in Seattle on Thursday, November 8th. This will be an excellent opportunity for you to learn more about their brand new distributed, peer-to-peer database solution, which I believe will revolutionize SQL cloud database technology in the 21th century.  I have been personally following NuoDB for months now and am very excited about the architecture and capabilities of this innovative product. Wiqar Chaudry, NuoDB technology evangelist, will give a presentation and demonstration of their elastically scalable SQL cloud database in this Meetup event.  Prior to joining NuoDB, Wiqar was a Senior Architect at Epsilon, the data intelligence company with big brand name customers in insurance, consumer goods, etc.  He’s also going to discuss how NuoDB compares with Azure, the hometown favorite, and why cloud-based SQL deployment will pave the way for the future. I will be at the NuoDB MeetUp to briefly talk about my own experiences with NuoDB and will be giving away some signed copies of my latest book as well will have some interesting goodies. So please join me and the NuoDB team at their Meetup event. RSVP here. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: PostADay, SQL, SQL Authority, SQL Query, SQL Server, SQL Tips and Tricks, T SQL, Technology Tagged: NuoDB

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  • Slow MySQL query....only sometimes

    - by Shane N
    I have a query that's used in a reporting system of ours that sometimes runs quicker than a second, and other times takes 1 to 10 minutes to run. Here's the entry from the slow query log: # Query_time: 543 Lock_time: 0 Rows_sent: 0 Rows_examined: 124948974 use statsdb; SELECT count(distinct Visits.visitorid) as 'uniques' FROM Visits,Visitors WHERE Visits.visitorid=Visitors.visitorid and candidateid in (32) and visittime>=1275721200 and visittime<=1275807599 and (omit=0 or omit>=1275807599) AND Visitors.segmentid=9 AND Visits.visitorid NOT IN (SELECT Visits.visitorid FROM Visits,Visitors WHERE Visits.visitorid=Visitors.visitorid and candidateid in (32) and visittime<1275721200 and (omit=0 or omit>=1275807599) AND Visitors.segmentid=9); It's basically counting unique visitors, and it's doing that by counting the visitors for today and then substracting those that have been here before. If you know of a better way to do this, let me know. I just don't understand why sometimes it can be so quick, and other times takes so long - even with the same exact query under the same server load. Here's the EXPLAIN on this query. As you can see it's using the indexes I've set up: id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY Visits range visittime_visitorid,visitorid visittime_visitorid 4 NULL 82500 Using where; Using index 1 PRIMARY Visitors eq_ref PRIMARY,cand_visitor_omit PRIMARY 8 statsdb.Visits.visitorid 1 Using where 2 DEPENDENT SUBQUERY Visits ref visittime_visitorid,visitorid visitorid 8 func 1 Using where 2 DEPENDENT SUBQUERY Visitors eq_ref PRIMARY,cand_visitor_omit PRIMARY 8 statsdb.Visits.visitorid 1 Using where I tried to optimize the query a few weeks ago and came up with a variation that consistently took about 2 seconds, but in practice it ended up taking more time since 90% of the time the old query returned much quicker. Two seconds per query is too long because we are calling the query up to 50 times per page load, with different time periods. Could the quick behavior be due to the query being saved in the query cache? I tried running 'RESET QUERY CACHE' and 'FLUSH TABLES' between my benchmark tests and I was still getting quick results most of the time. Note: last night while running the query I got an error: Unable to save result set. My initial research shows that may be due to a corrupt table that needs repair. Could this be the reason for the behavior I'm seeing? In case you want server info: Accessing via PHP 4.4.4 MySQL 4.1.22 All tables are InnoDB We run optimize table on all tables weekly The sum of both the tables used in the query is 500 MB MySQL config: key_buffer = 350M max_allowed_packet = 16M thread_stack = 128K sort_buffer = 14M read_buffer = 1M bulk_insert_buffer_size = 400M set-variable = max_connections=150 query_cache_limit = 1048576 query_cache_size = 50777216 query_cache_type = 1 tmp_table_size = 203554432 table_cache = 120 thread_cache_size = 4 wait_timeout = 28800 skip-external-locking innodb_file_per_table innodb_buffer_pool_size = 3512M innodb_log_file_size=100M innodb_log_buffer_size=4M

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  • Best pattern for storing (product) attributes in SQL Server

    - by EdH
    We are starting a new project where we need to store product and many product attributes in a database. The technology stack is MS SQL 2008 and Entity Framework 4.0 / LINQ for data access. The products (and Products Table) are pretty straightforward (a SKU, manufacturer, price, etc..). However there are also many attributes to store with each product (think industrial widgets). These may range from color to certification(s) to pipe size. Every product may have different attributes, and some may have multiples of the same attribute (Ex: Certifications). The current proposal is that we will basically have a name/value pair table with a FK back to the product ID in each row. An example of the attributes Table may look like this: ProdID AttributeName AttributeValue 123 Color Blue 123 FittingSize 1.25 123 Certification AS1111 123 Certification EE2212 123 Certification FM.3 456 Pipe 11 678 Color Red 999 Certification AE1111 ... Note: Attribute name would likely come from a lookup table or enum. So the main question here is: Is this the best pattern for doing something like this? How will the performance be? Queries will be based on a JOIN of the product and attributes table, and generally need many WHEREs to filter on specific attributes - the most common search will be to find a product based on a set of known/desired attributes. If anyone has any suggestions or a better pattern for this type of data, please let me know. Thanks! -Ed

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  • Struggling with a data modeling problem

    - by rpat
    I am struggling with a data model (I use MySQL for the database). I am uneasy about what I have come up with. If someone could suggest a better approach, or point me to some reference matter I would appreciate it. The data would have organizations of many types. I am trying to do a 3 level classification (Class, Category, Type). Say if I have 'Italian Restaurant', it will have the following classification Food Services Restaurants Italian However, an organization may belong to multiple groups. A restaurant may also serve Chinese and Italian. So it will fit into 2 classifications Food Services Restaurants Italian Food Services Restaurants Chinese The classification reference tables would be like the following: ORG_CLASS (RowId, ClassCode, ClassName) 1, FOOD, Food Services ORG_CATEGORY(RowId, ClassCode, CategoryCode, CategoryName) 1, FOOD, REST, Restaurants ORG_TYPE (RowId, ClassCode, CategoryCode, TypeCode, TypeName) 100, FOOD, REST, ITAL, Italian 101, FOOD, REST, CHIN, Chinese 102, FOOD, REST, SPAN, Spanish 103, FOOD, REST, MEXI, Mexican 104, FOOD, REST, FREN, French 105, FOOD, REST, MIDL, Middle Eastern The actual data tables would be like the following: I will allow an organization a max of 3 classifications. I will have 3 GroupIds each pointing to a row in ORG_TYPE. So I have my ORGANIZATION_TABLE ORGANIZATION_TABLE (OrgGroupId1, OrgGroupId2, OrgGroupId3, OrgName, OrgAddres) 100,103,NULL,MyRestaurant1, MyAddr1 100,102,NULL,MyRestaurant2, MyAddr2 100,104,105, MyRestaurant3, MyAddr3 During data add, a dialog could let the user choose the clssa, category, type and the corresponding GroupId could be populated with the rowid from the ORG_TYPE table. During Search, If all three classification are chosen, It will be more specific. For example, if Food Services Restaurants Italian is the criteria, the where clause would be 'where OrgGroupId1 = 100' If only 2 levels are chosen Food Services Restaurants I have to do 'where OrgGroupId1 in (100,101,102,103,104,105, .....)' - There could be a hundred in that list I will disallow class level search. That is I will force selection of a class and category The Ids would be integers. I am trying to see performance issues and other issues. Overall, would this work? or I need to throw this out and start from scratch.

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  • Building a News-feed that comprises posts "created by user's connections" && "on the topics user is following"

    - by aklin81
    I am working on a project of Questions & Answers website that allows a user to follow questions on certain topics from his network. A user's news-feed wall comprises of only those questions that have been posted by his connections and tagged on the topics that he is following(his expertise topics). I am confused what database's datamodel would be most fitting for such an application. The project needs to consider the future provisions for scalability and high performance issues. I have been looking at Cassandra and MySQL solutions as of now. After my study of Cassandra I realized that Simple news-feed design that shows all the posts from network would be easy to design using Cassandra by executing fast writes to all followers of a user about the post from user. But for my kind of application where there is an additional filter of 'followed topics', (ie, the user receives posts "created by his network" && "on topics user is following"), I could not convince myself with a good schema design in Cassandra. I hope if I missed something because of my short understanding of cassandra, perhaps, can you please help me out with your suggestions of how this news-feed could be implemented in Cassandra ? Looking for a great project with Cassandra ! Edit: There are going to be maximum 5 tags allowed for tagging the question (ie, max 5 topics can be tagged on a question).

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  • Modifying my website to allow anonymous comments

    - by David
    I write the code for my own website as an educational/fun exercise. Right now part of the website is a blog (like every other site out there :-/) which supports the usual basic blog features, including commenting on posts. But I only have comments enabled for logged-in users; I want to alter the code to allow anonymous comments - that is, I want to allow people to post comments without first creating a user account on my site, although there will still be some sort of authentication involved to prevent spam. Question: what information should I save for anonymous comments? I'm thinking at least display name and email address (for displaying a Gravatar), and probably website URL because I eventually want to accept OpenID as well, but would anything else make sense? Other question: how should I modify the database to store this information? The schema I have for the comment table is currently comment_id smallint(5) // The unique comment ID post_id smallint(5) // The ID of the post the comment was made on user_id smallint(5) // The ID of the user account who made the comment comment_subject varchar(128) comment_date timestamp comment_text text Should I add additional fields for name, email address, etc. to the comment table? (seems like a bad idea) Create a new "anonymous users" table? (and if so, how to keep anonymous user ids from conflicting with regular user ids) Or create fake user accounts for anonymous users in my existing users table? Part of what's making this tricky is that if someone tries to post an anonymous comment using an email address (or OpenID) that's already associated with an account on my site, I'd like to catch that and prompt them to log in.

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  • Schema design: many to many plus additional one to many

    - by chrisj
    Hi, I have this scenario and I'm not sure exactly how it should be modeled in the database. The objects I'm trying to model are: teams, players, the team-player membership, and a list of fees due for each player on a given team. So, the fees depend on both the team and the player. So, my current approach is the following: **teams** id name **players** id name **team_players** id player_id team_id **team_player_fees** id team_players_id amount send_reminder_on Schema layout ERD In this schema, team_players is the junction table for teams and players. And the table team_player_fees has records that belong to records to the junction table. For example, playerA is on teamA and has the fees of $10 and $20 due in Aug and Feb. PlayerA is also on teamB and has the fees of $25 and $25 due in May and June. Each player/team combination can have a different set of fees. Questions: Are there better ways to handle such a scenario? Is there a term for this type of relationship? (so I can google it) Or know of any references with similar structures?

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