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Diagram Relationships

Use the Database Diagram to view a high-level, visual representation of an object and those objects which may be related to it. This helps you easily identify relationships between tables via foreign keys. You can use the Database Diagram to:

• Understand the impact of changes.

• Identify join predicates when writing complex queries for reports.

• Understand the level of normalization of data when de-normalizing for performance or to save space.

• Understand entity relationships so you can better use the data in applications or reports.

To diagram a relationship

1. Click and double-click tables, views, or synonyms in the Object Explorer to add them to the Database Diagram window. You can also drag these objects to add them to the window. This method is useful if you want to add objects without setting the relationship types to display or the reference levels.

2. Drag a column from one object to a column in a second object where you want to create a relationship.

   Notes:

   • This feature does not add new objects to the diagram if a relationship exists; it only displays relationships between objects already in the diagram.

   • A line between objects indicates any existing relationships.

   • A indicates the referencing table, and a indicates the referenced table.

3. To reduce the number of columns that display in a large table, right-click the table and select Manage Hidden Columns. You can then hide any unnecessary columns to better understand the critical information.

4. To view the data type, nullable columns, and any comments for a selected object, right-click the object and select Show Column Details.
5. To view object details for a selected object, press SHIFT+F4, or double-click the object.
6. To add notes, right-click the Diagram pane, column, or object and select Notes. See Add Notes for more information.
7. To find a descriptive value for an ID column, right-click the ID column and select Find Lookup Table. See Find Lookup Tables for more information.

Tips:

• When opening a previously saved Database Diagram file, you can right-click the Diagram pane and select Refresh to get the latest objects from the database, including added/removed columns and data type updates.

  An * in the title of the object indicates that the saved version differs from the database version.

• You can right-click an object to show or hide dependencies, column details, or individual columns within the object.
• To specify the type of relationships to display in the diagram and the number of levels of referential tables to include, specify options in Tools | Options | Database | Diagramming.
• Toad automatically saves a backup copy of any modified diagram file in the Application Data Directory to avoid losing your work. When you restart Toad after an unexpected close, Toad checks the timestamp on the backup file against the original file, and opens the file that has the latest timestamp. The document recovery option is in Tools | Options | Environment | General.