I have tried looking for a entity relationship model using the schema of distributed database but I found diagrams as it:
or I found entity relationship models but they are not using the schema of distributed database like this...
I did next diagram but teacher said me it is not using the Distributed database schema. How can i convert it to istributed database schema??
Related
The two concepts confused me a lot recently.
Snowflake Database more refers to the data service and its website address as below:
https://www.snowflake.com/
This is more like a data platform or data warehouse on the cloud that provides SQL engine functionalities.
On the other hand, Snowflake schema is more like an algorithm that design database schema.
Are they totally two different things and just have the same name coincidently?
Databases and schemas are used to organize data stored in Snowflake:
A database is a logical grouping of schemas. Each database belongs to a single Snowflake account.
A schema is a logical grouping of database objects (tables, views, etc.). Each schema belongs to a single database.
Together, a database and schema comprise a namespace in Snowflake.
Source: https://docs.snowflake.com/en/sql-reference/ddl-database.html
The following is a sample logical model created using Oracle SQL Developer Data Modeler:
After engineering the model to a relational model, the resulting model is the following:
Is the above model considered to be a Physical Model? I believe this is a physical model, but the fact that it's called a relational model is making me have doubts.
From 1keydata:
Physical data model represents how the model will be built in the database. A physical database model shows all table structures, including column name, column data type, column constraints, primary key, foreign key, and relationships between tables.
What you have there represents what needs to be implemented in your database.
The relational model is "an approach to managing data using a structure and language consistent with first-order predicate logic" [Wikipedia]. In high level both diagrams follow the relational model.
I'm creating a new visual studio web site using MVC4/webapi that will go against a database of 75 preexisting tables (not perfect in terms of foreign keys, etc.). I'm thinking that I will create an ado.net entity data model and select all my tables. then, when my tables change I will do the "update model".
With my linq2sql projects, I always ran sqlmetal against all my tables all the time to keep things in sync and that worked fairly well.
Is my plan to have all my tables in one ado.net entity data model reasonable? what pitfalls might I run into? Is it better to have lots of ado.net entity data models? I've tried having multiple ado.net entity models in other projects and I seem to constantly be getting my connection strings doubled in my web.config.
I did do a search on SO and did not find any discussions that directly addressed my concern.
If you followed your plan, you would miss out on an opportunity to have an entity model simpler than your database model:
Your application almost certainly doesn't need all 75 tables.
You would be missing the opportunity to consider a series of 1-1 tables as a single entity
You would be missing the opportunity to use inheritance in your model
You would be missing the opportunity to keep junction tables out of your model
You would be losing one of the greatest advantages of Entity Framework over LINQ to SQL: it does not need to stay one-to-one with the database.
Can anyone give me an idea about database flow diagram in my SqlServer Server Management Studio? I have a database (ERBIA) in my server; I want to know about the database relationship among different tables.
You can simply click on this:
And then select the tables for which you wish to create diagrams (graphs)
By database flow diagram I think you mean an Entity Relationship Diagram (ERD). There are a number of 3rd party tools that exist to create ERDs. ERWin, Visio, ER/Studio are some examples.
These tools can read the database schema information and create a diagram and draw relationship lines based on the Foreign Key constraints. You can edit the diagrams and depending on the tool update the database or generate a DDL script for the database changes.
SQL Server also includes a database designer, but it should be noted there is no separation from a logical model and the physical model. This means if you draw a line from one table to another indicating a relationship a FK will actually be created when you save the diagram. For some scenarios this would be a problem.
I'm new in developing in MVC and I have some doubts in how to build the Models. I don't know if I must build them in terms of Database Tables or in other terms.
I have for example this 5 tables:
Domain
Category_Domains
Countries_Domains
Categories
Countries
How can i Build a Models to do actions in these Database Tables. Should I built the SQL commands to Insert, Delete and Update for each one of these Tables or I should do other thing than this?
Sorry if I not explain well.
The best advice I can give you is to look into the entity framework. Using this framework, you can create a data connection to your SQL database and the framework will create your model based on your table structure, including relationships.
Doing this will ensure your database is modelled correctly and kept in sync at all times