Creating E/R Diagrams with Visio - Super User
Download FMC-Visio Stencils for free. Tool support for creating FMC* diagrams [ Block diagrams, Petri nets, Entity-Relationship diagrams. ER Diagram tutorial covering everything you need to learn about entity relationship diagrams. Learn about ER diagram symbols, how to draw. However, we will show you how to: ❖ Start Visio Professional. ❖ Select the Crow's Foot entity relationship diagram (ERD) option. ❖ Create the entities and define.
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. 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.
Create a Database Model (also known as Entity Relationship 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. 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.
Set extended properties for tables and views Depending on your database management system DBMSyou may be able to set extended properties for tables or views to determine where they are stored. Double-click the table or view whose extended properties you want to set, and in the Database Properties window, in the Categories list, click Extended.
Create check clauses Use check clauses to ensure that the data that is entered into a column is within a particular range of values. For example, you can create a check clause that requires the data in a column called "Age" to be over Double-click the table to open the Database Properties window. Under Categories, click Columns and then click the column that you want to add a check clause to.
On the Check tab of the Column Properties dialog box, enter the constraints that you want. The check clause is added to the Code window under Local code. Create stored procedures and user-defined functions Use stored procedures and user-defined functions to create packets of code that you can reuse to perform the same actions repeatedly.
The major difference between the two is that a user-defined function returns a value, whereas the stored procedure executes code without returning a value. Click Global Code and then click New. On the Properties tab of the Code Editor, click the kind of code that you want to create, and type a name for the code. On the Body tab, type the code and then click OK. Create triggers Triggers cause SQL code that you specify in the trigger to run when a particular event occurs in the database.
Under Categories, click Triggers, and then click Add. On the Properties tab, type a name for the trigger. The trigger is added to the Code window under Local code. Can't find the database model features? Most likely, your edition of Microsoft Office Visio doesn't include the features that you are looking for. The name of the edition is in the top line of text in the dialog box.
Using Visio to create ER Diagrams
Microsoft Office Visio Professional supports the reverse engineering features for the Database Model Diagram template that is, using an existing database to create a model in Visiobut it does not support forward engineering that is, using a Visio database model to generate SQL code.
You can find the full suite of database modeling features, including both reverse engineering and forward engineering, in Visio for Enterprise Architects. On the Database menu, point to Options, and then click Document.
If you have not already associated the Visio database driver with a particular ODBC data source, click Setup to do so now. Select the data source of the database you are updating. If you have not already created a data source for the existing database, click New to do so now. When you create a new source, its name is added to the Data Sources list.
Download Visio Add-in for Database Modeling from Official Microsoft Download Center
When you are satisfied with your settings, click Next. Follow the instructions in any driver-specific dialog boxes. For example, in the Connect Data Source dialog box, type a user name and password, and then click OK.
If your data source isn't password protected, click OK. Select the check boxes for the type of information that you want to extract, and then click Next. Some items may be grayed out because not all systems support all the kinds of elements the wizard can extract.
Select the check boxes for the tables and views, if any that you want to extract, or click Select All to extract them all, and then click Next. If you are reverse engineering an Excel worksheet and don't see anything in this list, then it is likely that you need to name the range of cells that contain the column headings in your spreadsheet.
If you selected the Stored Procedures check box in step 5, 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 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.