I am following a SQL tutorial, it states
Database administrators often use relationship diagrams to help demonstrate how database tables are connected.
However,I tried every corner of mysql workbench but failed to find such a well-organized diagram.
How could I see the database structure as the diagram shows?
Looks like you didn't find the modeling part of MySQL Workbench yet. Walk through the tutorials to reverse engineer a schema and create an EER model from it.
You can customize colors and figure sizes + positions, organize a diagram with layers for better overview and change the notation (crow food etc.). Search for modeling with MySQL Workbench for more tips.
I learned long time ago database structure. But as I see on your picture, the diagram shows columns of tables and the relations between them.
1:N - means from the other table allowed to reference more than 1 records
1:1 - means from the other table allowed to reference only one record.
Example: relation between customers and orders.
The orders can have many customers_id and same customers as well. Because one customer can send more order.
You can find customer_id in order table too.
Related
I created an entity-relationship diagram (logical model) and engineered it to a relational model.
The tables were generated. Now I need to use them from the connection XE as you see in the picture.
The tables I made can only be seen on the data modeler design view in the "Browser", how do I get them on the connection "XE" to generate data dictionary, etc?
There are three possibilities:
you just need to expand the tables item in the tree to see your tables
You are looking in the wrong schema/user - go down to Other Users, and find the schema those tables belong to
The tables do not exist in the current database
If #3 is the issue, you would need to create them, possibly using the information in your Data Model - that is, you can generate the DDL/SQL scripts for those tables.
Then taking those scripts, run them while connected to the appropriate database/schema.
Disclaimer: I'm an Oracle employee and the product manager for these tools.
I'm new to this but I just installed Oracle Database 19c and SQL Developer. I am successfully connected to the HR sample schema. I can query against the HR tables such as HR.EMPLOYEES, etc.. However, in the Connections pane, when I expand the tables under this connection, there is a long list of tables starting with AQ$_INTERNET_AGENTS_PRIVS and a big list of other tables, but I can't see any of the HR tables? Where are they? Is this a view setting maybe?
This is for practice/homework. While it still seems to work, I can't figure out what the problem is. Researched here and other locations on the web.
The UI shows you the tables (and other objects) that belong to the schema for the user you have logged into.
So if you login in as HR, you'll see the tables for HR.
Otherwise if you want to see objects belonging to a different schema, navigate to the 'Other Users' node.
Or if you have synonyms in your schema which point to tables in another schema, you can ask SQL Developer to display those
And now when I look at my Tables list for my user that doesn't have any tables..
I talk about this in a bit more detail here.
As part of my final thesis, I must transform a relational database in a graph-oriented database, specifically a PostgreSQL database into a Neo4j embedded database. Now, the way is the problem. In Rik Van Bruggen's book: Learning Neo4j, he mentions a data import process using ETL activities with Trascend and MuleSoft tools, but in their official sites, there's no documentation about how to do it, neither help documentation nor examples. Apart from these tools, what other ways can I use to transform this information without using my own code?
Some modeling advice:
A well normalized relational model, which was not yet denormalized for performance reasons can be translated into the equivalent graph model.
Graph model shapes are mostly driven by use-cases, so there will be opportunity for optimization and model evolution afterwards.
A good, normalized Entity-Relationship diagram often already represents a decent graph model.
So if you still have the orignal ER diagram available, try to use it as a guide.
Here are some tips that help you with the transformation:
Each entity table is represented by a label on nodes
Each row in a table is a node
Columns on those tables become node properties.
Remove technical primary keys, keep business primary keys
Add unique constraints for business primary keys, add indexes for frequent lookup attributes
Replace foreign keys with relationships to the other table, remove them afterwards
Remove data with default values, no need to store those
Data in tables that is denormalized and duplicated might have to be pulled out into separate nodes to get a cleaner model.
Indexed column names, might indicate an array property (like email1, email2, email3)
JOIN tables are transformed into relationships, columns on those tables become relationship properties
It is important to have an understanding of the graph model before you start to import data, then it just becomes the task of hydrating that model.
LOAD CSV might be your best option, but of course it means outputting a CSV first. Here are some great resources:
http://neo4j.com/docs/stable/query-load-csv.html
http://watch.neo4j.org/video/112447027
http://jexp.de/blog/2014/06/load-csv-into-neo4j-quickly-and-successfully/
http://jexp.de/blog/2014/10/load-cvs-with-success/
http://www.markhneedham.com/blog/2014/10/23/neo4j-cypher-avoiding-the-eager/
I've also written a ruby gem which lets you write a little ruby code to import data from various sources. It's called neo4apis. You can look at the neo4apis-twitter gem to get an idea for how it works:
https://github.com/neo4jrb/neo4apis-twitter/
https://github.com/neo4jrb/neo4apis-twitter/blob/master/lib/neo4apis/twitter.rb
I've actually been wanting to implement a neo4apis-activerecord to make it easy to import from SQL with ActiveRecord
You can not directly export data from relational and import to neo4j.
Because these are two different database structures.
Relational Database -
A relational database is a set of tables containing data fitted into predefined categories. Each table (which is sometimes called a relation) contains one or more data categories in columns. Each row contains a unique instance of data for the categories defined by the columns.
Graph-oriented database -
A graph database is essentially a collection of nodes and edges. Each node represents an entity (such as a person or business) and each edge represents a connection or relationship between two nodes.
Sollution To your Problem-
First, you need to design Neo4j Data structure. e.g What will be the nodes you required, what will be the relationships between the nodes.
After that you create Script in your application language to fetch data from relational database and insert it into neo4j.
Load CSA is a option to Import/Export (backup) functionality with graph database. you can not directly Export/Import data from Relational DB to Graph DB
Our database has about 500 tables we'd like to use in our EF model. Of those I'd be happy to start with 50 or fewer just to get our feet wet after working in plain ADO.net for years.
The problem is, our SQL server contains many thousands of other tables that exist in our database that have been created through the years and many that are dynamically generated. Believe it or not:
select count(*) from INFORMATION_SCHEMA.TABLES
73261
So that's a lot of tables. I have found that pretty much every tool I've tried to design, build or template EF models or entities either hangs or does not return a list of tables. Even SQL Server Object Explorer in VS2012 won't list the tables and instead shows the Tables folder with a little "x" over the icon. So I can't even select a subset of tables.
What options do I have for using EF? Is there a template where I can explicitly define the tables that I want to use entities for? Even with 50 tables, I don't want to hand code each one in an empty EDMX.
Using a Database / Code First approach and avoiding connecting Visual Studio to the database at all (i.e. don't create an edmx, or connect with server explorer) would allow you to do this easily. It does not give you any of the Model First advantages, but I think it sounds like your project would be better served with a Database / Code First approach anyway as:
You have an existing Model, and are not looking to push changes from your EDMX to the DB
You are looking to implement this on a subset of your database
This link has a good summation ( Code-first vs Model/Database-first ) with the caveat that in you case a Database/Code First approach does not have you pushing changes from code to the Database, so the last two bullets under code first apply less, and yours is a Database/Code First hybrid.
With 70k tables I think that any GUI is going to be tricky. When I am saying Database / Code First, I am trying to convey that you are not using the code to create / define and update your Database. Someone may be able to answer this more succinctly / accurately?
I now this is an old question. But for those who land here on a google search. The only tool I have found that actually works with thousands of tables is The Sharp Factory.
It is an ORM. Pretty simple to use. So if you are looking for an ORM that can work with a large number of tables and does not require you to write "POCOS" or "Mappings" or SQL then this is the tool.
You can find it here: The Sharp Factory
How is database normalization related to ER Modelling??
What comes first??
Or should both be implemented at the same time??
I feel modeling should come first in a highly normalized database design.
Creating the model allows you to think through how the tables will relate to one another and also allows you to envision what tables you'll need to use when writing your join queries.
Using a tool such as MySQL Workbench or Toad Data Modeler , depending on your target database vendor, can even generate SQL commands to build the tables, constraints, and indexes directly from the model. This is useful because it ensures the tables are created exactly as you designed them.
Also, when making changes to the model, some tools like those mentioned above will even allow you to "update" your schema by issuing the necessary statements required to do so.
So in short, for a project with more than one table, I'd always model it first. It also makes it easier for developers to understand how the tables function and relate at a glance rather than having to read through DDL to understand it.
Modeling can even be fun!
A model created with MySQL Workbench:
Hope this helps!