Sql server 2005 entity relationship diagram definition

What is database Diagram in SQL Server ? How it is different from ERD?

sql server 2005 entity relationship diagram definition

This definition explains the meaning of entity relationship diagram, also known as ERD, and Expert advice: How to create an ERD in Oracle SQL Developer. SQL Server Management Studio tutorials. In this tutorial, I will show you how to create an ER diagram with Microsoft SQL Server Management Studio (SSMS). Include views in the diagrams; Define and show virtual relationships that are. What we call "database diagram" in SQL Server is an "Entity Relationship Diagram". You can open the "database diagrams" node and.

You can read about other symbol notation here. I find that the Crow's Foot notation is a little easier to read on small pictures, but you can use any type you like, as long as your team agrees on the standard you want to use. A word is also warranted here about the software that you can use to create these diagrams.

sql server 2005 entity relationship diagram definition

There are packages specifically designed to work with an underlying database which will create the first drafts all the way through to the SQL Statements needed to create the database. These packages can cost thousands of dollars to obtain and take weeks of training to fully use. There are also tools such as Microsoft's Visio that will do much the same thing for less money and a shorter learning curve investment.

You can also use any graphics program, if all you're after is the documentation part. All you really need is a pencil and paper to create the diagram, as long as you follow the agreed-on symbols. Let's get to those symbols. I need to describe the entities, their attributes, and relationships between the entities. Because it's a graphic, the ERD describes a lot of information in a very comprehensive way.

sql server 2005 entity relationship diagram definition

You'll recall from previous articles that entities are the basic units that you work with, which normally represent a group of data elements you'll make into a table. Entities are normally discovered from the business requirements for a database as the nouns in the sentence. Entities will eventually become tables in your finished database. Entities are represented by two shapes. A box like this one represents a 'parent' or owning entity: Here's where I'll deviate a bit from the standard.

ERD Tutorial: How to Design and Generate SQL Server DB?

Notice that the box above has square edges. That means this entity stands alone — nothing else is needed. We call this a "parent" entity. If an entity must have some other entity to exist, like a child in real life, I use a rounded box to indicate that - like this one: The name of the entity is written above the box. As I explain in the articles on the business requirements for this sample project, I can have a client that hasn't started the formal project yet.

ER Model in hindi (Simple & Easy Explain)

You'll also recall that I can't have a project without a client, so clients own projects. This simple difference in shape denotes whether an entity is a parent or child.

Attributes are also nouns in the business requirements document, but they are further descriptions of the entity. For instance, blue is a color of socks. In this case, color is an attribute of sock, and blue is the value of that particular sock's color. Close the tables frame and you will have the selected tables in the diagram editor.

As in our case we choose HumanResources. You can create a table in the diagram editor, work on it and as you save the diagram the table will be created in your database. Once the diagram is saved the table will be created and will be accessible for all operations. Right click on column GroupCode on which the primary key is required to be created. Choose option "Set Primary Key" as shown in the diagram.

A frame will appear like in SSMS table designer. Add the new key configuration parameters for the key the same way as for the table designer and click "Close". Create relations between tables through database diagrams in SSMS Like table designer in SSMS you can create all types of relationships between tables through database diagrams.

sql server 2005 entity relationship diagram definition

Right click on a table where a foreign key will reside. So right click on the Department table and click on "Relationships There you can configure parameters and relationships. Is there any change script available? Luckily you also have an option to get a script for changes performed through the diagram editor.

Right click on a table for which a change script is required to be generated. The last option in the menu is to generate a change script for DDL operations on the table.

This option will only be enabled if there are any changes. Click the menu item and a dialog box will pop-up to save the script. Get more detailed view of tables In the default format, database diagrams do not provide any information other than names for columns of tables.

Getting started with SQL Server database diagrams

We can not see the data types or NULL options of columns in these tables. To further utilize many features of SQL Server database diagrams, we are required to have detailed information about the columns of each table. To display detailed information, select all or required tables in the diagram editor.

sql server 2005 entity relationship diagram definition

Then right click on any selected table and choose standard view as shown in the following image Now you can see more column information in all tables. In this menu there is also an option for a customized table view. Removing a table from SSMS database diagram editor or from database Using the delete button on any number of selected tables will just remove the tables from the diagram.

However you can delete any table permanently from the database along with removing it from the diagram. For this task you have to right click on the table and select "Delete Tables from Database".

If you choose to delete tables from a database then a confirmation dialog will appear for confirmation of the delete operation. Deleting a relationship in SSMS database diagram editor The delete button will not work for deleting relationships in diagram editor. Relationships may be deleted by right clicking on the relation or you can select a relationship and then delete it through the Database Diagrams menu. A confirmation dialog will appear to confirm the delete operation for the relationship.

sql server 2005 entity relationship diagram definition

To delete multiple relations at one time you may select multiple and use either the Database Diagrams menu or right click on any of the selected relationships to perform the delete operation.

A little formatting in SSMS database diagrams editor As more tables are added, these may not be arranged for easy viewing.

To change the arrangement of the diagrams you can right click in the database diagram editor or use the Database Diagrams menu of SSMS as shown below.

How to create ER diagram?

Add text to diagrams To make the diagrams more readable you can add text. To add text in your diagram, right click anywhere in the diagram and choose "New Text Annotation". A text box will appear, you can write text and to format the text, right click inside the text box and select the formatting options.