I got a .mvb file from company, the relationship are complicated and Tables are a lot, I wonder how could I see the relationship between the tables piece by piece, to understand the relationship and database quickly.
Try this:
Model-diagram Properties
And then:
Arrange -autolayout
Related
At school we are supposed to create a Model in MySQL Workbench from this ER diagram
The black arrow means total, non-disjoint relationship.
The definition of that relationship is the following:
super-entity is always part of one or more sub-entities
I am struggling with creating that model. I found somewhere that there is a way with triggers, but I did not figure out how. I am still a beginner.
Is there a way to visually represent the tables in a sql database; showing relationships, if there are any, between the different tables? Thank you.
In SQL server, under the database name is a folder named "Database Diagrams". Right click and "add new database diagram".
Click on the tables you wish to include, then hit the "Add" button.
Provided you have already setup your relationships the connections will be shown, 1 to many, many to many, etc. You can name and save, then if you add relationships after the fact, they will automatically appear (but if you add tables after the fact, you will have to manually add them to your saved diagram(s)).
You can move the tables and relationship chains around to make it more clear, and add labels for headers, etc. If you have a lot of tables I find zooming out while working on arranging things in a logical order easiest.
Use database diagrams. Here is a link that may help: http://www.mssqltips.com/sqlservertip/1816/getting-started-with-sql-server-database-diagrams/
Database Schemas are not my strong point however I'm making a Recipe Schema and would like some input from experts on this before I move forward with my code.
InnoDB with relations.
Tabels Recipe_Steps and Recipe_Step_Ingredients have relations setup for ON UPDATE RESTRICT and ON DELETE CASCADE.
Ok I rearranged things a bit, I think I made it more simple without loosing any functionality. Usually recipes list the ingredients and the instructions separate so I don't think I need the steps to be linked to the ingredients.
What do you guys think?
One suggestion is that Recepie steps table is not connected with recepie ingredients.... you might want to do that since different ingredients are used in different steps .
I'm studying from "Database Design and Development: A Visual Approach" by Frost, Day, and van Slyke.
It presents relationships in Chapter 5 that indicate partial or total and disjoint or overlap specialization.
Unfortunately, I cannot figure out how to diagram such a thing in MySQL Workbench. A Google search doesn't turn up much either. I found a result about a person asking about them only in SQL to be told that "he doesn't understand the relational database model', which was really annoying.
My book gives examples where this can save diskspace and states that it's a perfectly valid part of the relational model. But it appears to be missing from Workbench.
How can I exhibit specialization in Workbench? The book uses "Student" and "Athlete" and "Councilmember" tables as their example, where a student can be an athlete, student council member, both, or none.
EDIT: Found some links to people asking more or less the same question. Here's the link to a person in the mysql forums. He got an annoying reply that basically ignored his question. Here's a link to the question at DevShed. He got no reply. I now suspect that the functionality does not exist in workbench, despite the name EER suggesting it does.
Ok i think i have found the solution!
If you click a line between two entities you ll see 2 boxes for each side of the connection that says Mandatory. This is total participation. At least it worked for me. You ll notice that total participation has no O on the side that participates but if you uncheck it you ll get a partial participation with O on the side of the entity.
i'm also a beginner for SQL and I had similar problem before, but i think i've clearer mind now, so I'd like to share with you.
If I'm not taught wrong, specifications you mentioned (partial or total and disjoint or overlap specialization) can not be diagramed in ER diagram (ie, entity-relationship diagram), but mysql (and other well-known database softwares) does have this covered. Basically, you enforce this kind of constraints through trigger, check and assertation. And I'm also using mysql workbench, you can certainly create triggers.
If you want to know more about trigger, check and assertation, read jellomonkey's answer:
what is the difference between triggers, assertions and checks (in database)
I believe that when you double click the entity at the bottom you can create indexes and foreign keys between entities. Once created the diagram updated showing lines representing the relationships between entities.
If you provide further details on the structure and relationships of the the table I could try to represent it for you.
Is it something like this you are after http://grab.by/ank7
I need to create an ERD for our DB system. As it happens, there are lots and lots of tables, and no one really understands much of it. What's more, the same DB has tables for different applications, so not all tables are relevant to my application. I need an ERD for only my application's tables.
I tried creating ERD from MySQL workbench. It allows me to select a subset of the tables to put on an ERD, but that's the problem: I don't know which tables to select ( One of the reasons to build the diagram in the first place :-) ).
What I do know are some of the 'main' tables involved. What I'm looking for is this: I tell the tool some 5-10 of these main tables I'm interested in, and the tool automatically picks up all the tables that are linked to these tables, and creates the ERD for them.
Any pointers?
Otherwise, I'll have to live with building my list of tables manaully, one by one...
http://www.fabforce.net/ has a nice tool called DBDesigner, I have used this in the past for some reverse engineering on a datamodel.