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The Relations dialog box gives four options for maintaining referential integrity. These options are as follows:
• No action: This option, set as the default, prohibits users from updating or deleting any record in the
master table if related records exist in the transaction table.
• Update cascade: This option enables users to update or delete the referenced field, causing all related
records in any of the transaction tables to also be updated or deleted.
• Set NULL: With this option, if the master record is deleted or updated, all related fields are assigned a NULL
value.
• Set default: This option assigns a predetermined default value to all related fields if the master record is
deleted or updated.
Step 2: Select the tables in the Tables Involved section
Step 3: Select the fields from the tables in the Fields Involved section to modify the relationship.
Step 4: Click on the OK button.
Deleting the Relationship
Relationship once created can be easily removed by deleting them using the given steps:
Step 1: Click on Tools menu. A drop-down menu will appear.
Step 2: Select Relationships option from the menu. The Relation window will appear.
Step 3: Right-click on the relationship thread and select the Delete option.
The relationship between tables will be removed thus showing that now the two tables are not related.
Create a database Library with the tables - Books in stock, Books issued, Books lost/
damaged.
uiz Bee 1. Design the structure of all the 3 tables with the primary key, foreign key.
2. Link the three tables and name the relationships, if possible, between different tables in
a database.
3. Can a referential integrity be set between Books in stock and Books issued? If yes, explain
the concept with reference to the given two tables.
4. Give the steps to delete a relationship in the LibreOffice Base.
326 Trackpad Information Technology (Ver. 1.0)-X

