primary-key

问题 i keep hearing that i shouldn't be using primary keys in my asp.net mvc url for example: /Users/Edit/1243 what is the issue here? what is the alternative, putting in user names? as you want it to be unique, it seems like primary key is the cleanest option thoughts? 回答1: I don't see any problem with putting the primary key on the URL (neither do the creators of Stack Overflow and countless other sites either for that matter). One thing that is often done is to supply the primary key and also

问题 I have an excel file which gets updated on a daily basis i.e the data is always different every time. I am pulling the data from the Excel sheet into the table using Talend . I have a primary key Company_ID defined in the table. The error I am facing is that the Excel sheet has few duplicate Company_ID values. It will also pick up more duplicate values in the future as the Excel file will be updated daily. I want to choose the first record where the Company ID field is 1 and the record doesn

问题 I'm working with a table that has an integer column and a foreign key. This integer has to be incremental, but it has to start again in 1 when the foreign key is changed. Example: Foreign 1, int col : 1 , 2 , 3... Foreign 2, int col: 1 ,2 , 3, 4, 5 ... Foreign 3, int col: 1, 2 This is my mapping so far: (Of course this doesn't does the trick) public class Documento implements ModelEntity{ private static final long serialVersionUID = 11233L; /*PK*/ @Id @Column(name = "id") @GeneratedValue

问题 What is the best way to get records from the database based on the selected primary keys? I am able to get the primary keys of the selected (checked) rows from a gridview, and now need to retrieve the corresponding records from the database for those selected compound primary keys. If the rows are using just one primary key, it would have been easier. I could have just concatenated the primary keys (comma delimited) and use it in a WHERE IN clause. But the rows are using three primary keys

问题 I have a PHP page which interacts with this small MySQL database table with a simple structure. ID , Name , Address are the fields. ID is the primary key. +------+------------+-------------+ | ID | Name | Country | |______|____________|_____________| | E001 | Stephen | America | | E002 | John | Britain | | E003 | Kate | Canada | | E004 | Carlos | Spain | | E005 | James | Australia | |______|____________|_____________| If I remove the record at E003 , it looks like this. +------+------------+-

问题 I need to create a relationship between ReportID which is part of a composite primary key. This is my code written for Microsoft SQL Server: CREATE TABLE Tableone ( ReportID varchar UNIQUE, Date date, Line ommited PRIMARY KEY (ReportNumber, Date) ) CREATE TABLE Tabletwo ( Line omitted Line ommited ReportID varchar UNIQUE FOREIGN KEY REFERENCES Tableone(ReportID), Line ommited PRIMARY KEY (XX, XXX, ReportID) ) UPDATE: We have specifically been asked to set both ReportID and Date as the primary

问题 I'm using a model produced with Devart Entity Developer (.edml file, which I understand is mostly similar to .edmx) to generate Entity classes whose relations are initialized in a DbContext class. The database schema specifies no PK for View1, and all columns are nullable. But the code generation assumes that for views lacking a primary key, all columns are the key. I.e., the .ssdl has all columns under the Key element and the DbContext has .IsRequired() specified on all, like so: ssdl

问题 This question already has an answer here : How to change the primary key to be non-clustered? (1 answer) Closed last year . I am new to SQL and I have a SQL file and when I execute it the following error occurs: Msg 1913, Level 16, State 1, Line 463 The operation failed because an index or statistics with name 'DDT_PK' already exists on table 'DAILY_DATA_TYPE'. The error occurs when running this statement: CREATE UNIQUE NONCLUSTERED INDEX DDT_PK ON [DATE_DATA_TYPE]([TYPE_ID]) GO ALTER TABLE

问题 I'm using MySQL workbench's EER tool to make the database design for an application I'm developing. it is very important to track data changes on the DB, so i was following this post which makes a lot of sense the accepted answer. the problem im having is that i am not good understanding the primary keys so im a little confused on how this should work, since every time a change is made there will be another row inserted with the same Id, therefore the DB wouldn't allow it am I right? And i

问题 I am using SQL Server Express and importing via the Import Wizard so no code to offer really. The error is shown here: Error 0xc0202009: Data Flow Task 1: SSIS Error Code DTS_E_OLEDBERROR. An OLE DB error has occurred. Error code: 0x80004005. An OLE DB record is available. Source: "Microsoft SQL Server Native Client 11.0" Hresult: 0x80004005 Description: "The statement has been terminated.". An OLE DB record is available. Source: "Microsoft SQL Server Native Client 11.0" Hresult: 0x80004005