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  • How to Set Customer Table with Multiple Phone Numbers? - Relational Database Design

    - by user311509
    CREATE TABLE Phone ( phoneID - PK . . . ); CREATE TABLE PhoneDetail ( phoneDetailID - PK phoneID - FK points to Phone phoneTypeID ... phoneNumber ... . . . ); CREATE TABLE Customer ( customerID - PK firstName phoneID - Unique FK points to Phone . . . ); A customer can have multiple phone numbers e.g. Cell, Work, etc. phoneID in Customer table is unique and points to PhoneID in Phone table. If customer record is deleted, phoneID in Phone table should also be deleted. Do you have any concerns on my design? Is this designed properly? My problem is phoneID in Customer table is a child and if child record is deleted then i can not delete the parent (Phone) record automatically.

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  • What is the best way to archive data in a relational database?

    - by GenericTypeTea
    I have a bit of an issue with a particular aspect of a program I'm working on. I need the ability to archive (fix) a table so that a change anywhere in the system will not affect the results it returns. This is the basic structure of what I need to fix: Recipe --> Recipe (as sub recipe) Recipe --> Ingredients So, if I fix a Recipe, I need to ensure all the sub recipes (including all the sub recipes sub recipes and so forth) are fixed and all its ingredients are fixed. The problem is that the sub recipe and ingredients still need to be modifiable as they are used by other recipes that are not fixed. I came up with a solution whereby I serialize (with protobuf-net) a master object that deals with the recipe and all the sub recipes and ingredients and save the archive data to a table like follows: Archive{ ReferenceId, (i.e. RecipeId) ReferenceTypeId, (i.e. Recipe) ArchiveData varbinary(max) } Now, this works great and is almost perfect... however I totally forgot (I'd love to blame the agile development mentally, however this was just short sighted) that this information needs to be reported on. As far as I'm aware I can't think how I could inflate the serialized data back into my Recipe Object and use it in a Report. I'm using the standard SQL 2005 report services at the moment. Alternatively, I guess I could do the following: Duplicate every table and tag the word "Archive" on the end of the table name. This would then give me an area of specific archive data... but ignoring my simplified example, there'd actually be about 15 tables duplicated. Add a nullable, non-foreign key property called "CopiedFromId" to every table that contains fixed data and duplicate every record that the recipe (and all it's sub recipes and all their sub recipes) touches. Create some sort of denormalised structure that could be restored from at a later date to the original, unfixed recipe. Although I think this would be like option 1 and involve a lot of extra tables. Anyway, I'm at a total loss and do not like any of the ideas particularly. Can anyone please advise the best course of action? EDIT: Or 4) Create tables specific to what the report requires and populate them with the data when the user clicks the report button? This would cause about 4 extra tables for the report in question.

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  • What resources will help me understand the fundamentals of Relational Database Systems.

    - by Rachel
    This are few of the fundamental database questions which has always given me trouble. I have tried using google and wiki but I somehow I miss out on understanding the functionality rather than terminology. If possible would really appreciate if someone can share more insights on this questions using some visual representative examples. What is a key? A candidate key? A primary key? An alternate key? A foreign key? What is an index and how does it help your database? What are the data types available and when to use which ones?

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  • What is the best URL strategy to handle multiple search parameters and operators?

    - by Jon Winstanley
    Searching with mutltiple Parameters In my app I would like to allow the user to do complex searches based on several parameters, using a simple syntax similar to the GMail functionality when a user can search for "in:inbox is:unread" etc. However, GMail does a POST with this information and I would like the form to be a GET so that the information is in the URL of the search results page. Therefore I need the parameters to be formatted in the URL. Requirements: Keep the URL as clean as possible Avoid the use of invalid URL chars such as square brackets Allow lots of search functionality Have the ability to add more functions later. I know StackOverflow allows the user to search by multiple tags in this way: http://stackoverflow.com/questions/tagged/c+sql However, I'd like to also allow users to search with multiple additional parameters. Initial Design My design is currently to do use URLs such as these: http://example.com/search/tagged/c+sql/searchterm/transactions http://example.com/search/searchterm/transactions http://example.com/search/tagged/c+sql http://example.com/search/tagged/c+sql/not-tagged/java http://example.com/search/tagged/c+sql/created/yesterday http://example.com/search/created_by/user1234 I intend to parse the URL after the search parameter, then decide how to construct my search query. Has anyone seen URL parameters like this implemented well on a website? If so, which do it best?

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  • Any tips of how to handle hierarchical trees in relational model?

    - by George
    Hello all. I have a tree structure that can be n-levels deep, without restriction. That means that each node can have another n nodes. What is the best way to retrieve a tree like that without issuing thousands of queries to the database? I looked at a few other models, like flat table model, Preorder Tree Traversal Algorithm, and so. Do you guys have any tips or suggestions of how to implement a efficient tree model? My objective in the real end is to have one or two queries that would spit the whole tree for me. With enough processing i can display the tree in dot net, but that would be in client machine, so, not much of a big deal. Thanks for the attention

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  • What do the & and | operators do in a batch file?

    - by Sam
    I'm debugging a batch file left behind by an old employee and I've come across the line: @nmake -f makefile /E 2>&1 | tee %LOGFILEPATH% What does this do? I know what @nmake -f makefile /E does and I know what tee %LOGFILEPATH% does, but I can't find anything on what the 2>&1 | means. Thanks

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  • What are the Options for Storing Hierarchical Data in a Relational Database?

    - by orangepips
    Good Overviews One more Nested Intervals vs. Adjacency List comparison: the best comparison of Adjacency List, Materialized Path, Nested Set and Nested Interval I've found. Models for hierarchical data: slides with good explanations of tradeoffs and example usage Representing hierarchies in MySQL: very good overview of Nested Set in particular Hierarchical data in RDBMSs: most comprehensive and well organized set of links I've seen, but not much in the way on explanation Options Ones I am aware of and general features: Adjacency List: Columns: ID, ParentID Easy to implement. Cheap node moves, inserts, and deletes. Expensive to find level (can store as a computed column), ancestry & descendants (Bridge Hierarchy combined with level column can solve), path (Lineage Column can solve). Use Common Table Expressions in those databases that support them to traverse. Nested Set (a.k.a Modified Preorder Tree Traversal) First described by Joe Celko - covered in depth in his book Trees and Hierarchies in SQL for Smarties Columns: Left, Right Cheap level, ancestry, descendants Compared to Adjacency List, moves, inserts, deletes more expensive. Requires a specific sort order (e.g. created). So sorting all descendants in a different order requires additional work. Nested Intervals Combination of Nested Sets and Materialized Path where left/right columns are floating point decimals instead of integers and encode the path information. Bridge Table (a.k.a. Closure Table: some good ideas about how to use triggers for maintaining this approach) Columns: ancestor, descendant Stands apart from table it describes. Can include some nodes in more than one hierarchy. Cheap ancestry and descendants (albeit not in what order) For complete knowledge of a hierarchy needs to be combined with another option. Flat Table A modification of the Adjacency List that adds a Level and Rank (e.g. ordering) column to each record. Expensive move and delete Cheap ancestry and descendants Good Use: threaded discussion - forums / blog comments Lineage Column (a.k.a. Materialized Path, Path Enumeration) Column: lineage (e.g. /parent/child/grandchild/etc...) Limit to how deep the hierarchy can be. Descendants cheap (e.g. LEFT(lineage, #) = '/enumerated/path') Ancestry tricky (database specific queries) Database Specific Notes MySQL Use session variables for Adjacency List Oracle Use CONNECT BY to traverse Adjacency Lists PostgreSQL ltree datatype for Materialized Path SQL Server General summary 2008 offers HierarchyId data type appears to help with Lineage Column approach and expand the depth that can be represented.

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  • What's the maximum number of operators you that can be used in an if statement?

    - by DMinGod
    Hi, i'm using jquery and I'm trying to validate a form. My question is - What is the maximum number of tests can you give in a single if statement. function cc_validate () { if ($("#name").val() == "" || $("#ship_name").val() == "" || $("#address").val() == "" || $("#city").val() == "" || $("#ship_city").val() == "" || $("#state").val() == "" || $("#ship_state").val() == "" || $("#postal_code").val() == "" || isNaN($("#postal_code").val()) || $("#phone").val() == "" || $("#ship_phone").val() == "" || isNaN($("#phone").val()) || isNaN($("#ship_phone").val()) || $("#mobile_number").val() == "" || $("#ship_mobile_number").val() == "" || isNaN($("#mobile_number").val()) || isNaN($("#ship_mobile_number").val()) || $("#email").val() == "") { return false; } else { return true; } }

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  • How can I create a small relational database in MySQL?

    - by Sergio Tapia
    I need to make a small database in MySQL that has two tables. Clothes and ClotheType Clothes has: ID, Name, Color, Brand, Price, ClotheTypeID ClotheType has: ID, Description In Microsoft SQL it would be: create table Clothes( id int, primary key(id), name varchar(200), color varchar(200), brand varchar(200), price varchar(200), clothetypeid int, foreign key clothetypeid references ClotheType(id) ) I need this in MySQL.

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  • What resources will help me understand the fundamentals of Relational Database Design.

    - by Rachel
    This are few of the fundamental database questions which has always given me trouble. I have tried using google and wiki but I somehow I miss out on understanding the functionality rather than terminology. If possible would really appreciate if someone can share more insights on this questions using some visual representative examples. What is a key? A candidate key? A primary key? An alternate key? A foreign key? What is an index and how does it help your database? What are the data types available and when to use which ones?

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  • Bitwise operators and converting an int to 2 bytes and back again.

    - by aKiwi
    first time user, Hi guys! So hopefully someone can help.. My background is php so entering the word of lowend stuff like, char is bytes, which are bits.. which is binary values.. etc is taking some time to get the hang of ;) What im trying to do here is sent some values from an Ardunio board to openFrameWorks (both are c++). What this script currently does (and works well for one sensor i might add) when asked for the data to be sent is.. int value_01 = analogRead(0); // which outputs between 0-1024 unsigned char val1; unsigned char val2; //some Complicated bitshift operation val1 = value_01 &0xFF; val2 = (value_01 >> 8) &0xFF; //send both bytes Serial.print(val1, BYTE); Serial.print(val2, BYTE); Apparently this is the most reliable way of getting the data across.. So now that it is send via serial port, the bytes are added to a char string and converted back by.. int num = ( (unsigned char)bytesReadString[1] << 8 | (unsigned char)bytesReadString[0] ); So to recap, im trying to get 4 sensors worth of data (which im assuming will be 8 of those serialprints?) and to have int num_01 - num_04... at the end of it all. Im assuming this (as with most things) might be quite easy for someone with experience in these concepts.. Any help would be greatly appreciated. Thanks

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  • Is it better to use a relational database or document-based database for an app like Wufoo?

    - by mboyle
    I'm working on an application that's similar to Wufoo in that it allows our users to create their own databases and collect/present records with auto generated forms and views. Since every user is creating a different schema (one user might have a database of their baseball card collection, another might have a database of their recipes) our current approach is using MySQL to create separate databases for every user with its own tables. So in other words, the databases our MySQL server contains look like: main-web-app-db (our web app containing tables for users account info, billing, etc) user_1_db (baseball_cards_table) user_2_db (recipes_table) .... And so on. If a user wants to set up a new database to keep track of their DVD collection, we'd do a "create database ..." with "create table ...". If they enter some data in and then decide they want to change a column we'd do an "alter table ....". Now, the further along I get with building this out the more it seems like MySQL is poorly suited to handling this. 1) My first concern is that switching databases every request, first to our main app's database for authentication etc, and then to the user's personal database, is going to be inefficient. 2) The second concern I have is that there's going to be a limit to the number of databases a single MySQL server can host. Pretending for a moment this application had 500,000 user databases, is MySQL designed to operate this way? What if it were a million, or more? 3) Lastly, is this method going to be a nightmare to support and scale? I've never heard of MySQL being used in this way so I do worry about how this affects things like replication and other methods of scaling. To me, it seems like MySQL wasn't built to be used in this way but what do I know. I've been looking at document-based databases like MongoDB, CouchDB, and Redis as alternatives because it seems like a schema-less approach to this particular problem makes a lot of sense. Can anyone offer some advice on this?

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  • What's The Best Object-Relational Mapping Tool For .NET?

    - by Icono123
    I've worked on a few Java web projects and we've always used Hibernate for our data object layer. I haven't worked on a large scale ASP.NET site and I'm unsure which solution to choose. I'm tempted to try NHibernate, but I don't like the fact that they use so many third party libraries. I found this list on Wikipedia of available ORM software: http://en.wikipedia.org/wiki/List_of_object-relational_mapping_software#.NET What ORM have you used? Was it easy to use? Would you recommend using it again? Was it used on a small, medium, or large project? Would you write your own? Thanks.

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  • Some questions about special operators i've never seen in C++ code.

    - by toto
    I have downloaded the Phoenix SDK June 2008 (Tools for compilers) and when I'm reading the code of the Hello sample, I really feel lost. public ref class Hello { //-------------------------------------------------------------------------- // // Description: // // Class Variables. // // Remarks: // // A normal compiler would have more flexible means for holding // on to all this information, but in our case it's simplest (if // somewhat inelegant) if we just keep references to all the // structures we'll need to access as classstatic variables. // //-------------------------------------------------------------------------- static Phx::ModuleUnit ^ module; static Phx::Targets::Runtimes::Runtime ^ runtime; static Phx::Targets::Architectures::Architecture ^ architecture; static Phx::Lifetime ^ lifetime; static Phx::Types::Table ^ typeTable; static Phx::Symbols::Table ^ symbolTable; static Phx::Phases::PhaseConfiguration ^ phaseConfiguration; 2 Questions : What's that ref keyword? What is that sign ^ ? What is it doing protected: virtual void Execute ( Phx::Unit ^ unit ) override; }; override is a C++ keyword too? It's colored as such in my Visual Studio. I really want to play with this framework, but this advanced C++ is really an obstacle right now. Thank you.

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  • How to map combinations of things to a relational database?

    - by Space_C0wb0y
    I have a table whose records represent certain objects. For the sake of simplicity I am going to assume that the table only has one row, and that is the unique ObjectId. Now I need a way to store combinations of objects from that table. The combinations have to be unique, but can be of arbitrary length. For example, if I have the ObjectIds 1,2,3,4 I want to store the following combinations: {1,2}, {1,3,4}, {2,4}, {1,2,3,4} The ordering is not necessary. My current implementation is to have a table Combinations that maps ObjectIds to CombinationIds. So every combination receives a unique Id: ObjectId | CombinationId ------------------------ 1 | 1 2 | 1 1 | 2 3 | 2 4 | 2 This is the mapping for the first two combinations of the example above. The problem is, that the query for finding the CombinationId of a specific Combination seems to be very complex. The two main usage scenarios for this table will be to iterate over all combinations, and the retrieve a specific combination. The table will be created once and never be updated. I am using SQLite through JDBC. Is there any simpler way or a best practice to implement such a mapping?

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  • Are there any less costly alternatives to Amazon's Relational Database Services (RDS)?

    - by swapnonil
    Hi All, I have the following requirement. I have with me a database containing the contact and address details of at least 2000 members of my school alumni organization. We want to store all that information in a relation model so that This data can be created and edited on demand. This data is always backed up and should be simple to restore in case the master copy becomes unusable. All sensitive personal information residing in this database is guaranteed to be available only to authorized users. This database won't be online in the first 6 months. It will become online only after a website is built on top of it. I am not a DBA and I don't want to spend time doing things like backups. I thought Amazon's RDS with it's automatic backup facility was the perfect solution for our needs. The only problem is that being a voluntary organization we cannot spare the monthly $100 to $150 fees this service demands. So my question is, are there any less costlier alternatives to Amazon's RDS?

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  • In Python, are there builtin functions for elementwise boolean operators over boolean lists?

    - by bshanks
    For example, if you have n lists of bools of the same length, then elementwise boolean AND should return another list of that length that has True in those positions where all the input lists have True, and False everywhere else. It's pretty easy to write, i just would prefer to use a builtin if one exists (for the sake of standardization/readability). Here's an implementation of elementwise AND: def eAnd(*args): return [all(tuple) for tuple in zip(*args)] example usage: >>> eAnd([True, False, True, False, True], [True, True, False, False, True], [True, True, False, False, True]) [True, False, False, False, True] thx

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  • Are there any less costlier alternatives to Amazon's Relational Database Services (RDS)?

    - by swapnonil
    Hi All, I have the following requirement. I have with me a database containing the contact and address details of at least 2000 members of my school alumni organization. We want to store all that information in a relation model so that This data can be created and edited on demand. This data is always backed up and should be simple to restore in case the master copy becomes unusable. All sensitive personal information residing in this database is guaranteed to be available only to authorized users. This database won't be online in the first 6 months. It will become online only after a website is built on top of it. I am not a DBA and I don't want to spend time doing things like backups. I thought Amazon's RDS with it's automatic backup facility was the perfect solution for our needs. The only problem is that being a voluntary organization we cannot spare the monthly $100 to $150 fees this service demands. So my question is, are there any less costlier alternatives to Amazon's RDS?

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  • MySQL searching using many 'like' operators: is there a better way?

    - by DrAgonmoray
    I have a page that gets all rows from a table in a database, then displays the rows in an HTML table. That works great, but now I want to implement a 'search' feature. There is a searchbox, and search-terms are separated by a space. I am going to make it search three fields for the search terms, 'make' 'model' and 'type.' These three fields are VARCHAR(30). Currently if I wanted to search using 3 terms (say 'cool' 'abc' and '123') my query would look something like this. SELECT * FROM table WHERE make LIKE '%cool%' OR make LIKE '%abc%' OR make LIKE '%123%' OR model LIKE '%cool%' OR model LIKE '%abc%' OR model LIKE '%123%' OR type LIKE '%cool%' OR type LIKE '%abc%' OR type LIKE '%123%' That looks really bad, and it will get even worse if there are more search terms or more fields to search. My question to you: is there a better way to search? If so, what?

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  • Any tips of how to handle hierarchial trees in relational model?

    - by George
    Hello all. I have a tree structure that can be n-levels deep, without restriction. That means that each node can have another n nodes. What is the best way to retrieve a tree like that without issuing thousands of queries to the database? I looked at a few other models, like flat table model, Preorder Tree Traversal Algorithm, and so. Do you guys have any tips or suggestions of how to implement a efficient tree model? My objective in the real end is to have one or two queries that would spit the whole tree for me. With enough processing i can display the tree in dot net, but that would be in client machine, so, not much of a big deal. Thanks for the attention

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  • MySQL not using index on DATE when used with '<' or '>' operators?

    - by Haroldo
    I'm using explain to test these queries. The col type is DATE this uses index: explain SELECT events.* FROM events WHERE events.date = '2010-06-11' this doesnt explain SELECT events.* FROM events WHERE events.date >= '2010-06-11' index as follows (phpmyadmin) Action Keyname Type Unique Packed Field Cardinality Collation Null Comment Edit Drop PRIMARY BTREE Yes No event_id 18 A Edit Drop date BTREE No No date 0 A i notice cardinality is 0, though there are some rows with the same date..

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  • Which relational databases exist with a public API for a high level language?

    - by Jens Schauder
    We typically interface with a RDBMS through SQL. I.e. we create a sql string and send it to the server through JDBC or ODBC or something similar. Are there any RDBMS that allow direct interfacing with the database engine through some API in Java, C#, C or similar? I would expect an API that allows constructs like this (in some arbitrary pseudo code): Iterator iter = engine.getIndex("myIndex").getReferencesForValue("23"); for (Reference ref: iter){ Row row = engine.getTable("mytable").getRow(ref); } I guess something like this is hidden somewhere in (and available from) open source databases, but I am looking for something that is officially supported as a public API, so one finds at least a note in the release notes, when it changes. In order to make this a question that actually has a 'best' answer: I prefer languages in the order given above and I will prefer mature APIs over prototypes and research work, although these are welcome as well.

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  • What is the best signature for overloaded arithmetic operators in C++?

    - by JohnMcG
    I had assumed that the canonical form for operator+, assuming the existence of an overloaded operator+= member function, was like this: const T operator+(const T& lhs, const T& rhs) { return T(lhs) +=rhs; } But it was pointed out to me that this would also work: const T operator+ (T lhs, const T& rhs) { return lhs+=rhs; } In essence, this form transfers creation of the temporary from the body of the implementation to the function call. It seems a little awkward to have different types for the two parameters, but is there anything wrong with the second form? Is there a reason to prefer one over the other?

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