Developing ER-Diagram - ppt download
Outlook · OneDrive · Word · Excel · PowerPoint · OneNote · SharePoint Use the Entity Relationship stencil to model databases that are based on the See Can't find the database modeling features? for more information. the symbol set that you want to use and other table and relationship options, and then click OK. 17 ENTITY-RELATIONSHIP DIAGRAMS Crow's foot notation is a As its name suggests, it is the primary key of reference for the table and is. What is an Entity Relationship Diagram (ERD)? The process for identifying attributes is similar except now you want to look for and Crow's Foot Notation.
Relationship sets may involve more than two entity sets.
Simple and composite attributes. Single-valued and multivalued attributes Example: Domain — the set of permitted values for each attribute Attribute types: Attribute that has more than one value: Most useful in describing binary relationship sets.
Create a Database Model (also known as Entity Relationship diagram)
For a binary relationship set the mapping cardinality must be one of the following types: Rectangles represent entity set and diamonds represent relationship set. Price depends jointly on beer and bar. Notice arrow convention for multiway relationships: However, if price, say, depended only on the beer, then we could use two 2-way relationships: Many-one relationships from the connecting E.
Roles are indicated in E-R diagrams by labeling the lines that connect diamonds to rectangles. Role labels are optional, and are used to clarify semantics of the relationship 42 Specialization within an entity set that are distinctive from other entities in the set. These subgroupings become lower-level entity sets that have attributes or participate in relationships that do not apply to the higher-level entity set.
If you selected the Stored Procedures check box, select the procedures that you want to extract, or click Select All to extract them all, and then click Next. Select whether you want the reverse engineered items to be added automatically to the current page. You can choose to have the wizard automatically create the drawing, in addition to listing the reverse engineered items in the Tables and Views window.
If you decide not to have the drawing created automatically, you can drag the items from the Tables and Views window onto your drawing page to manually assemble the database model.
Drawing Entity Relationship Diagrams Using PowerPoint Tutorial
Review your selections to verify that you are extracting the information that you want, and then click Finish. The wizard extracts the selected information and displays notes about the extraction process in the Output window.
This ability is limited to only VisioModeler 2. On the Database tab, in the Model group, click Import, and then click the model type.
Type the path and file name for the model that you want to import, or click the Browse button to locate the model file, and then click Open. In the Import dialog box, click OK. Visio imports the file and displays its progress in the Output window.
The imported tables are displayed in the Tables and Views window. In the Tables and Views window, select the tables that you want to model, and then drag them onto the drawing page. After you create a database model diagram, the work of refining the diagram begins. You can add and customize tables and views, create relationships, and customize columns and data types.Entity Relationship Diagram (ERD) Training Video
Tables Use the Entity shape to create a table in your diagram. From either the Entity Relationship or Object Relational stencil, drag an Entity shape onto the drawing. Double-click the shape to open the Database Properties window.
Under Categories, click Definition and type a name for the table. Under Categories, click Columns, type a name, and choose a data type. Select the Req'd check box for columns that can't have null values. Select the PK primary key check box for columns that uniquely identify each row in the database table. Columns Use the Database Properties window to add or change properties for columns, including data types and primary keys.
Double-click the table in your diagram. In the Database Properties window, under Categories, click Columns. Click in the first empty Physical Name cell, and type a name. To change the data type for a column, click the column's Data Type field, and then select a data type from the list or type it into the list. For example, you can type decimal 8,2 or char To prevent null values, select the Req'd check box.
To specify that the column is a primary key, select the PK check box.
- Developing ER-Diagram
To see more column properties in addition to those that appear when you click the Columns category, select the column and then click Edit.
Relationships Relationships use primary and foreign keys to allow databases to match a row in one table with a row in a related table.
You can show those relationships in your diagram. In addition, you can set their cardinality for example, one-to-many and use either Crow's feet, Relational, or IDEF1X notation to show the cardinality. You can't show many-to-many relationships with any of these notations in the Database Model Diagram template. Create a relationship between tables: Make sure that both tables are visible in the diagram.
If you reverse engineered the model from an existing database, you may need to drag one or both from the Tables and Views window onto the drawing page. Double-click the table that you want for the primary key side of the relationship. In the grid, click the column that you want to use to uniquely identify each row in the table, and select the PK check box to set it as the primary key.
From the Object Relational or Entity Relationship stencil, drag a Relationship shape and drop it onto a blank space on the page. Connect the higher end to the table with the parent table. Connect the other end to the child table.
If the second table doesn't already contain a column with the same name as the primary key, the modeler adds it to the second table as a foreign key. If relationship lines disappear, on the Database tab, in the Manage group, click Display Options. On the Relationships tab, under Show, select the Relationships check box. Set the relationship's cardinality: In the Database Properties window, under Categories, click Miscellaneous.
Under Cardinality, choose the cardinality that best fits the relationship. For one-to-many relationships, the best choice is either Zero or more or One or more.
For one-to-one relationships, the best choice is either Zero or one or Exactly one. To make other refinements to your diagram such as creating indexes, check clauses, and triggers you can do the following: Create indexes Indexes improve the performance, or speed, of your database when you run a query. Open the database model diagram.
Double-click the table to which you want to add an index, and in the Database Properties window, in the Categories list, click Indexes.
Entity-Relationship Model - ppt download
In the Create Index dialog box, type a name for the index, and then click OK. In the Index Type list, select an option to create a unique or non-unique index. In the Indexed Columns list, select the Asc check box to create an index that has an ascending sort order, or clear the check box to create an index that has a descending sort order.
The database model diagram is updated. Create views You can think of a view as a saved query. Views are particularly handy if you need to repeatedly access the same information from multiple tables, or if you want to expose the data to users without letting them change the actual tables.