foreign-key-relationship

相关标签：javascript jquery android 多少钱 iPhone

Does defining foreign keys and table relationships have any effect on writing queries?

I was putting together a table in Mysql workbench and defining many-to-one relationships and which keys were foreign keys etc, and I know it put this in the actual Create script. So I\'m开发者_StackOv[详细]

2023-02-11 09:02 分类：问答
Does JPA support annotations (or xml tags declarations) for declaring a constraint like ON DELETE (set null, cascade, ...)?

I\'ve used JPA to create a database, more exactly the hibernate implementation of JPA. But anyway, at first, my question is related to JPA.[详细]

2023-02-11 05:34 分类：问答
Rails - how would you set up this HABTM relationship

I have a situation where Project can have many Tags (and vice versa), so I have set up a has_and_belongs_to_many 开发者_如何学Gorelationship between the two.[详细]

2023-02-10 19:36 分类：问答
Database design - composite key relationship issue

I had posted a similar question before, but this is more specific.Please have a look at the following diagram:[详细]

2023-02-09 22:59 分类：问答
one-to-many relationships with django

I intend to create a teaming system, where each team may contain multiple contestants. The co开发者_运维问答ntestants is actually auth.User. Something similar to:[详细]

2023-02-09 03:17 分类：问答
How to Implement Referential Integrity in Subtypes

I have the following tables in a relational database: [Sensor] LocationId [PK / FK -> Location] SensorNo [PK][详细]

2023-02-08 07:09 分类：问答
SQL Server Foreign Key "On Delete Set Null " constraint not working

I am using sql server express 2008 with mmse. i have set up a foreign key constraint between to tables and set the on delete constraint to \"set null\".[详细]

2023-02-06 21:13 分类：问答
GORM prevent creation of a foreign key constraint for a Domain

I am developing a web based application in Grails. I have come across a situation where I would like to try and suppress GORM from creating a foreign key constraint on a field in a table.[详细]

2023-02-06 17:21 分类：问答
SQL: Optional Foreign Keys

I have the following tables.... \"Floor\" (which has many) \"Area\" (which has many) \"Asset\", then I have a \"Task\" table.[详细]

2023-02-06 17:19 分类：问答
Relationship between entities in database

When describing relationships between entities have I understood it correct if it the occurrence of a primary key in the table, lets say A has in table B that determines whether it is a one-to-one, on[详细]

2023-02-05 17:29 分类：问答