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  • Negative Primary Keys

    - by bjax
    Are there any repercussions using Negative Primary Keys for tables (Identity Increment -1, Identity Seed -1 in SQL Server 2005)? The reason for this is we're creating a new database to replace an existing one. There are similar tables between the two databases and we'd like the "source" of the information to be transparent to our applications. The approach is to create views that unions tables from both databases. Negative PKs ensures the identities don't overlap.

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  • Database Modelling - Conceptually different entities but with near identical fields

    - by Andrew Shepherd
    Suppose you have two sets of conceptual entities: MarketPriceDataSet which has multiple ForwardPriceEntries PoolPriceForecastDataSet which has multiple PoolPriceForecastEntry Both different child objects have near identical fields: ForwardPriceEntry has MarketPriceDataSetId (foreign key to parent table) StartDate EndDate SimulationItemId ForwardPrice PoolPriceForecastEntry has PoolPriceForecastDataSetId (foreign key to parent table) StartDate EndDate SimulationItemId ForecastPoolPrice If I modelled them as separate tables, the only difference would be the foreign key, and the name of the price field. There has been a debate as to whether the two near identical tables should be merged into one. Options I've thought of to model this is: Just keep them as two independent, separate tables Have both sets in the one table with an additional "type" field, and a parent_id equalling a foreign key to either parent table. This would sacrifice referential integrity checks. Have both sets in the one table with an additional "type" field, and create a complicated sequence of joining tables to maintain referential integrity. What do you think I should do, and why?

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  • Request for comments: Ruby script that counts the length of a MySQL table name

    - by bakerjr
    Hi, I'm new at ruby and I would like to ask you guys if there's something that could improve my Ruby code. Here's my script: #!/usr/bin/ruby -w require 'mysql' dbh = Mysql.real_connect('localhost', 'db_user', 'password', 'db_table') tables = dbh.query('show tables') tables.each do |table| puts "#{table}" + " (" + "#{table}".length.to_s + ")" end I'd love to hear your comments. Thanks in advance

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  • Are GUID primary keys bad in theory, or just practice?

    - by Yarin
    Whenever I design a database I automatically start with an auto-generating GUID primary key for each of my tables (excepting look-up tables) I know I'll never lose sleep over duplicate keys, merging tables, etc. To me it just makes sense philosophically that any given record should be unique across all domains, and that that uniqueness should be represented in a consistent way from table to table. I realize it will never be the most performant option, but putting performance aside, I'd like to know if there are philosophical arguments against this practice?

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  • Is there an ORM that supports composition w/o Joins

    - by Ken Downs
    EDIT: Changed title from "inheritance" to "composition". Left body of question unchanged. I'm curious if there is an ORM tool that supports inheritance w/o creating separate tables that have to be joined. Simple example. Assume a table of customers, with a Bill-to address, and a table of vendors, with a remit-to address. Keep it simple and assume one address each, not a child table of addresses for each. These addresses will have a handful of values in common: address 1, address 2, city, state/province, postal code. So let's say I'd have a class "addressBlock" and I want the customers and vendors to inherit from this class, and possibly from other classes. But I do not want separate tables that have to be joined, I want the columns in the customer and vendor tables respectively. Is there an ORM that supports this? The closest question I have found on StackOverflow that might be the same question is linked below, but I can't quite figure if the OP is asking what I am asking. He seems to be asking about foregoing inheritance precisely because there will be multiple tables. I'm looking for the case where you can use inheritance w/o generating the multiple tables. Model inheritance approach with Django's ORM

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  • SqlServer2008 + expensive union

    - by Tim Mahy
    Hi al, we have 5 tables over which we should query with user search input throughout a stored procedure. We do a union of the similar data inside a view. Because of this the view can not be materialized. We are not able to change these 5 tables drastically (like creating a 6th table that contains the similar data of the 5 tables and reference that new one from the 5 tables). The query is rather expensive / slow what are our other options? It's allowed to think outside the box. Unfortunately I cannot give more information like the table/view/SP definition because of customer confidentiality... greetings, Tim

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  • Hibernate question hbm2ddl.auto possible values and what they do

    - by Suzan
    I really want to know more about the update, export and the values that could be given to hbm2ddl.auto. I need to know when to use the update and when not? And what is the alternative? These are changes that could happen over DB: New tables new columns in old tables columns deleted data type of a column changed a type of a column changed it attributes tables have been dropped values of a column has changed In each case what is the best solution?

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  • How to model a mutually exclusive relationship in sql server

    - by littlechris
    Hi, I have to add functionality to an existing application and I've run into a data situation that I'm not sure how to model. I am being restricted to the creation of new tables and code. If I need to alter the existing structure I think my client may reject the proposal..although if its the only way to get it right this is what I will have to do. I have an Item table that can me link to any number of tables, and these tables may increase over time. The Item can only me linked to one other table, but the record in the other table may have many items linked to it. Examples of the tables/entities being linked to are "Person", "Vehicle", "Building", "Office". These are all separate tables. Example of Items are "Pen", "Stapler", "Cushion", "Tyre", "A4 Paper", "Plastic Bag", "Poster", "Decoration" For instance a "Poster" may be allocated to a "Person" or "Office" or "Building". In the future if they add a "Conference Room" table it may also be added to that. My intital thoughts are: Item { ID, Name } LinkedItem { ItemID, LinkedToTableName, LinkedToID } The LinkedToTableName field will then allow me to identify the correct table to link to in my code. I'm not overly happy with this solution, but I can't quite think of anything else. Please help! :) Thanks!

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  • SqlServer2008 + expensive union all

    - by Tim Mahy
    Hi al, we have 5 tables over which we should query with user search input throughout a stored procedure. We do a union all of the similar data inside a view. Because of this the view can not be materialized. We are not able to change these 5 tables drastically (like creating a 6th table that contains the similar data of the 5 tables and reference that new one from the 5 tables). The query is rather expensive / slow what are our other options? It's allowed to think outside the box. Unfortunately I cannot give more information like the table/view/SP definition because of customer confidentiality... greetings, Tim

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  • Using an ORM with a database that has no defined relationships?

    - by Ahmad
    Consider a database(MSSQL 2005) that consists of 100+ tables which have primary keys defined to a certain degree. There are 'relationships' between tables, however these are not enforced with foreign key constraints. Consider the following simplified example of typical types of tables I am dealing with. The are clear relations between the User and City and Province tables. However, they key issues is the inconsistent data types in the tables and naming conventions. User: UserRowId [int] PK Name [varchar(50)] CityId [smallint] ProvinceRowId [bigint] City: CityRowId [bigint] PK CityDescription [varchar(100)] Province: ProvinceId [int] PK ProvinceDesc [varchar(50)] I am considering a rewrite of the application (in ASP.net MVC) that uses this data source as is similar in design to MVC storefront. However I am going through a proof of concept phase and this is one of the stumbling blocks I have come across. What are my options in terms of ORM choice that can be easily used and why? Should I even be considering an ORM? (The reason I ask this is that most explanations and tutorials all work with relatively cleanly designed existing databases, or newly created ones when compared to mine. I am thus having a very hard time trying to find a way forward with this problem) There is a huge amount of existing SQL queries, would a datamappper(eg IBatis.net) be more suitable since we could easily modify them to work and reuse the investment already made? I have found this question on SO which indicates to me that an ORM can be used - however I get the impression that this a question of mapping? Note: at the moment, the object model is not clearly defined as it was non-existent. The existing system pretty much did almost everything in SQL or consisted of overly complicated, and numerous queries to complete fucntionality. I am pretty much a noob and have zero experience around ORMs and MVC - so this an awesome learning curve I am on.

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  • What are the reasons *not* to use a GUID for a primary key?

    - by Yarin
    Whenever I design a database I automatically start with an auto-generating GUID primary key for each of my tables (excepting look-up tables) I know I'll never lose sleep over duplicate keys, merging tables, etc. To me it just makes sense philosophically that any given record should be unique across all domains, and that that uniqueness should be represented in a consistent way from table to table. I realize it will never be the most performant option, but putting performance aside, I'd like to know if there are philosophical arguments against this practice?

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  • How to isolate data per customer, Django powered website

    - by Sawwy
    I have recently started learning python and django and working on a project that includes building a website for collecting information from customers. I am currently trying to figure out best way to isolate the customer data (collected information is sensitive and should only be accessible by customer and the service provider). I found this post Postgresql - one database for everyone, or one-database per customer and my question is that can I automate the model inheritance with customer creation via admin? To be specific, when save() is called for adding customer via django admin, this should create the customer specific tables (create a new set of tables with 'company_name' -prefix). For more information of the environment, I have extended the basic user registration with custom UserProfile adding 'company' and 'role' fields for each user. Upon login, the 'company' of the user will be checked to filter out tables without the 'company_name' prefix. 'Role' will further filter the which company-specific tables and set rights (view, edit). will appreciate any suggestions if more elegant methods could be used to solve the data isolation problem than model inheritance.

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  • Trying to verify understanding of Foreign Keys MSSQL

    - by msarchet
    So I'm working on just a learning project to expose myself to doing some things I do not get to do at work. I'm just making a simple bug and case tracking app (I know there are a million this is just to work with some tools I don't get to). So I was designing my database and realized I've never actually used Foreign Keys before in any of my projects, I've used them before but never actually setting up a column as a FK. So I've designed my database as follows, which I think is close to correct (at least for the initial layout). However When I try to add the FK's to the linking Tables I get an error saying, "The tables present in the relationship must have the same number of columns". I'm doing this by in SQLSMS by going to the Keys 'folder' and adding a FK. Is there something that I am doing wrong here, I don't understand why the tables would have to have the same number of columns for me to add a FK relationship between the tables?

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  • Database Modelling - Conceptually different entities with near identical fields

    - by Andrew Shepherd
    Suppose you have two sets of conceptual entities: MarketPriceDataSet which has multiple ForwardPriceEntries PoolPriceForecastDataSet which has multiple PoolPriceForecastEntry Both different child objects have near identical fields: ForwardPriceEntry has StartDate EndDate SimulationItemId ForwardPrice MarketPriceDataSetId (foreign key to parent table) PoolPriceForecastEntry has StartDate EndDate SimulationItemId ForecastPoolPrice PoolPriceForecastDataSetId (foreign key to parent table) If I modelled them as separate tables, the only difference would be the foreign key, and the name of the price field. There has been a debate as to whether the two near identical tables should be merged into one. Options I've thought of to model this is: Just keep them as two independent, separate tables Have both sets in the one table with an additional "type" field, and a parent_id equalling a foreign key to either parent table. This would sacrifice referential integrity checks. Have both sets in the one table with an additional "type" field, and create a complicated sequence of joining tables to maintain referential integrity. What do you think I should do, and why?

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  • What could possibly be different between the table in a DataContext and an IQueryable<Table> when do

    - by Nate Bross
    I have a table, where I need to do a case insensitive search on a text field. If I run this query in LinqPad directly on my database, it works as expected Table.Where(tbl => tbl.Title.Contains("StringWithAnyCase") In my application, I've got a repository which exposes IQueryable objects which does some initial filtering and it looks like this var dc = new MyDataContext(); public IQueryable<Table> GetAllTables() { var ret = dc.Tables.Where(t => t.IsActive == true); return ret; } In the controller (its an MVC app) I use code like this in an attempt to mimic the LinqPad query: var rpo = new RepositoryOfTable(); var tables = rpo.GetAllTables(); // for some reason, this does a CASE SENSITIVE search which is NOT what I want. tables = tables.Where(tbl => tbl.Title.Contains("StringWithAnyCase"); return View(tables); The column is defiend as an nvarchar(50) in SQL Server 2008. Any help or guidance is greatly appreciated!

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  • MySQL Inserting into locked aliased table

    - by Whitey
    I am trying to insert data into a InnoDB MySQL table which is locked using an alias and I cannot for the life of me get it to work! The following works: LOCK TABLES Problems p1 WRITE, Problems p2 WRITE, Server READ; SELECT * FROM Problems p1; UNLOCK TABLES; But try and do an insert and it doesn't work (it claims there is a syntax error round the 'p1' in my INSERT): LOCK TABLES Problems p1 WRITE, Problems p2 WRITE, Server READ; INSERT INTO Problems p1 (SomeCol) VALUES(43534); UNLOCK TABLES; Help please!

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  • How do I design this link table?

    - by Soo
    Ok SO, I have a user table and want to define groups of users together. The best solution I have for this is to create three database tables as follows: UserTable user_id user_name UserGroupLink group_id member_id GroupInfo group_id group_name This method keeps the member and group information separate. This is just my way of thinking. Is there a better way to do this? Also, what is a good naming convention for tables that link two other tables?

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  • which is better, creating a materialized view or a new table?

    - by Carson
    I have some demanding mysql queries that are needed to grap same up-to-date datasets from 5-7 mysql tables. I am thinking of creating a table or materialized view to gather all demanding columns from other tables, so as to increase performance. If I create that table, I may need to do extra insert / update / delete operation each time other tables updated. if I create materialized view, I am worrying if the performance can be greatly improved. Because data from other tables are changing very frequently. Most likely, the view may need to be created first everytime before selecting it. Any ideas? e.g. how to cache? other extra measures I can do?

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  • Dataset holds a table called "Table", not the table I pass in?

    - by dotnetdev
    Hi, I have the code below: string SQL = "select * from " + TableName; using (DS = new DataSet()) using (SqlDataAdapter adapter = new SqlDataAdapter()) using (SqlConnection sqlconn = new SqlConnection(connectionStringBuilder.ToString())) using (SqlCommand objCommand = new SqlCommand(SQL, sqlconn)) { sqlconn.Open(); adapter.SelectCommand = objCommand; adapter.Fill(DS); } System.Windows.Forms.MessageBox.Show(DS.Tables[0].TableName); return DS; However, every time I run this code, the dataset (DS) is filled with one table called "Table". It does not represent the table name I pass in as the parameter TableName and this parameter does not get mutated so I don't know where the name Table comes from. I'd expect the table to be the same as the tableName parameter I pass in? Any idea why this is not so? EDIT: Important fact: This code needs to return a dataset because I use the dataRelation object in another method, which is dependent on this, and without using a dataset, that method throws an exception. The code for that method is: DataRelation PartToIntersection = new DataRelation("XYZ", this.LoadDataToTable(tableName).Tables[tableName].Columns[0], // Treating the PartStat table as the parent - .N this.LoadDataToTable("PartProducts").Tables["PartProducts"].Columns[0]); // 1 // PartsProducts (intersection) to ProductMaterial DataRelation ProductMaterialToIntersection = new DataRelation("", ds.Tables["ProductMaterial"].Columns[0], ds.Tables["PartsProducts"].Columns[1]); Thanks

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  • How do you select form elements in JQuery based upon an html table?

    - by Swoop
    I am working on some ASP.NET web forms which involves some dynamic generation, and I need to add some onClick helpers on the client side. I have a basic outline of something working, except for one huge problem. There are multiple HTML tables, each generated by a different ASP.NET web control. Each table can contain overlapping field names, which is causing a problem with my JQuery click event handlers. The click event handler is linking to unintended form fields in addition to the intended form field. I have provided a simplified sample version of the code below. This code is trying to set the value of textbox box1 when a particular radiobutton is selected in the table with id=thing1. Obviously, the jquery code will be triggered for the form fields in both tables. The tables are dynamically added to the webpage based upon different conditions. It is possible that no tables will be loaded, only 1 table, or both tables might load. In the future, other tables could be added. Each table comes from a different .net web control. Other than renaming the form fields to make sure they are unique across all user controls, is there a way to have JQuery act only on the intended form fields? In other words, could the table ID be incorporated into the JQuery code in a manner that does not become a nightmare to maintain later? <script> $(document).ready(function() { $("[id$=radio1_0]").click(function() { $("[id$=box1]").attr("value", ""); }); $("[id$=radio1_1]").click(function() { $("[id$=box1]").attr("value", "N/A"); }); </script> <table id="thing1"> <tr><td> <radiobuttonlist id="radio1"/> <listitem>yes</listitem> <listitem>no</listitem> </td></tr> <tr><td> <textbox id="box1"/> </td></tr> </table> <table id="thing2"> <tr><td> <radiobuttonlist id="radio1"/> <listitem>yes</listitem> <listitem>no</listitem> </td></tr> <tr><td> <textbox id="box1"/> </tr></td> </table>

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  • BULK INSERT from one table to another all on the server

    - by steve_d
    I have to copy a bunch of data from one database table into another. I can't use SELECT ... INTO because one of the columns is an identity column. Also, I have some changes to make to the schema. I was able to use the export data wizard to create an SSIS package, which I then edited in Visual Studio 2005 to make the changes desired and whatnot. It's certainly faster than an INSERT INTO, but it seems silly to me to download the data to a different computer just to upload it back again. (Assuming that I am correct that that's what the SSIS package is doing). Is there an equivalent to BULK INSERT that runs directly on the server, allows keeping identity values, and pulls data from a table? (as far as I can tell, BULK INSERT can only pull data from a file) Edit: I do know about IDENTITY_INSERT, but because there is a fair amount of data involved, INSERT INTO ... SELECT is kinda of slow. SSIS/BULK INSERT dumps the data into the table without regards to indexes and logging and whatnot, so it's faster. (Of course creating the clustered index on the table once it's populated is not fast, but it's still faster than the INSERT INTO...SELECT that I tried in my first attempt) Edit 2: The schema changes include (but are not limited to) the following: 1. Splitting one table into two new tables. In the future each will have its own IDENTITY column, but for the migration I think it will be simplest to use the identity from the original table as the identity for the both new tables. Once the migration is over one of the tables will have a one-to-many relationship to the other. 2. Moving columns from one table to another. 3. Deleting some cross reference tables that only cross referenced 1-to-1. Instead the reference will be a foreign key in one of the two tables. 4. Some new columns will be created with default values. 5. Some tables aren’t changing at all, but I have to copy them over due to the "put it all in a new DB" request.

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  • association of more than one model to a listview

    - by Veer
    I have 3 Tables in my database. Each table has 3 fields each, excluding the ID field. out of which 2 fields are of type nvarchar. None of the tables are related. My ListView in the application helps the user to search my database, the search being incremental. The search includes the nvarchar fields of the 3 tables ie, 6 fields in total. Eg: PhoneBook: Name, PhoneNo Notes: Title, Content Bookmarks: Name, url I've the models generated for the 3 tables. Now the ListBox should display the Ph.Name, Title and the Bo.Name fields. ie, It should be bound to them. But they are from different models. I also should be able to perform CRUD operation on the item searched. How would i do that? P.S: Separate ViewModels are created for each Model which are used for their respective views for handling those tables individually. But this is an integrated view where the user should be able to search everything. Also please somebody suggest me a better Title for this question:)

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  • MySQL help, counting information on last records

    - by ee12csvt
    I need some advice I have two tables, one holds unique serial numbers of items (items) and the other holds status changes and other information for these items (details) The Tables are set up as follows Item itemID itemName itemDate details detID itemID modlvl status detDate All items have at least one record in the details table, but over time the status has changed or the modification level has changed (Both of these are identified by numbers which are held in other appropriate tables) and a new record is created each time the status/modlvl changes I want to display a table on my webpage using php that identifies the different mod levels of the items and shows a count of each of the current status of the items EDIT Hi Ronnis, This is an example of the data in the tables and what I want to achieve The current Mod Levels range from 1 to 3 Status representations are 1 In Use 2 In Store 3 Being repaired 4 In Transit 5 For Disposal 6 Disposed 7 Lost Item itemID OrigMod created 1000 1 2009-10-01 22:12:12 1001 1 2009-10-01 22:12:12 1002 1 2009-10-01 22:12:12 1003 1 2009-10-01 22:12:12 1004 1 2009-10-01 22:12:12 1005 1 2009-10-01 22:12:12 1006 1 2009-10-01 22:12:12 1007 1 2009-10-01 22:12:12 1008 1 2009-10-01 22:12:12 1009 1 2009-10-01 22:12:12 1010 1 2009-10-01 22:12:12 Details detID itemID modlvl detDate status 1 1000 1 2009-10-01 1 2 1001 1 2009-10-01 1 3 1002 1 2009-10-01 1 4 1003 1 2009-10-01 1 5 1004 1 2009-10-01 1 6 1005 1 2009-10-01 1 7 1006 1 2009-10-01 1 8 1007 1 2009-10-01 1 9 1008 1 2009-10-01 1 10 1009 1 2009-10-01 1 11 1010 1 2009-10-01 1 12 1001 1 2010-02-01 2 13 1001 1 2010-02-03 4 14 1001 1 2010-03-01 3 15 1000 1 2010-03-14 2 16 1001 2 2010-04-01 4 17 1006 1 2010-04-01 2 18 1001 2 2010-04-03 2 19 1006 1 2010-04-14 4 20 1006 1 2010-05-01 5 21 1002 1 2010-05-02 2 22 1003 1 2010-05-10 2 23 1010 1 2010-06-01 2 24 1006 1 2010-06-18 6 25 1010 1 2010-07-01 7 26 1007 1 2010-07-02 2 27 1007 1 2010-07-04 4 28 1003 1 2010-07-10 2 29 1007 1 2010-07-11 3 30 1007 2 2010-07-12 4 31 1007 2 2010-07-15 2 32 1001 2 2010-08-31 1 33 1001 2 2010-09-10 2 34 1001 2 2010-10-01 4 35 1008 1 2010-10-01 2 36 1001 2 2010-10-05 3 37 1008 1 2010-10-05 4 38 1008 1 2010-10-10 3 39 1001 3 2010-10-20 4 40 1001 3 2010-10-25 2 Using the tables above I want to get this result MoLvl Use Store Repd Transit Displ Dispd Lost Total 1 3 3 1 0 0 1 1 9 2 0 1 0 0 0 0 0 1 3 0 1 0 0 0 0 0 1 Total 3 5 1 0 0 1 1 11

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  • Using Linq-To-SQL I'm getting some weird behavior doing text searches with the .Contains method. Loo

    - by Nate Bross
    I have a table, where I need to do a case insensitive search on a text field. If I run this query in LinqPad directly on my database, it works as expected Table.Where(tbl => tbl.Title.Contains("StringWithAnyCase")) // also, adding in the same constraints I'm using in my repository works in LinqPad // Table.Where(tbl => tbl.Title.Contains("StringWithAnyCase") && tbl.IsActive == true) In my application, I've got a repository which exposes IQueryable objects which does some initial filtering and it looks like this var dc = new MyDataContext(); public IQueryable<Table> GetAllTables() { var ret = dc.Tables.Where(t => t.IsActive == true); return ret; } In the controller (its an MVC app) I use code like this in an attempt to mimic the LinqPad query: var rpo = new RepositoryOfTable(); var tables = rpo.GetAllTables(); // for some reason, this does a CASE SENSITIVE search which is NOT what I want. tables = tables.Where(tbl => tbl.Title.Contains("StringWithAnyCase"); return View(tables); The column is defiend as an nvarchar(50) in SQL Server 2008. Any help or guidance is greatly appreciated!

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