How to define foreign keys in database navicat

Defining foreign keys in Navicat can ensure data integrity. The steps are as follows: Edit the column and check "Foreign Keys". Select the parent table and parent column. Set update and deletion rules, such as cascading updates, prohibitions, etc. save Changes.

How to define foreign keys in Navicat

Defining foreign keys in Navicat can ensure the consistency between database tables Data integrity and consistency. The following is a step-by-step guide:

1. Create a foreign key table

In the table where you need to create a foreign key, right-click the column and select "Edit Column" .

2. Specify the foreign key column

Under the "Data Type" tab, find the "Foreign Key" option and select it.

3. Select the parent table

In the "Parent table" field, select the parent table whose primary key you want to reference.

4. Select the parent column

In the "Parent column" field, select the column in its parent table that you want to reference.

5. Set update and delete rules

In the "Update Rules" and "Delete Rules" drop-down menus, select the updates and deletes that you want to apply to the foreign key column Rules of operation.

6. Save changes

Click the Save button to save the changes to the column.

Common update and delete rules:

• Cascading updates: When the primary key value in the parent table is updated, it will also Updates the value referenced in the foreign key table.
• Cascading delete: When the primary key value in the parent table is deleted, the value referenced in the foreign key table will also be deleted.
• Prohibited: The primary key value in the parent table is not allowed to be updated or deleted because a record that references the value still exists in the foreign key table.
• Set NULL: When the primary key value in the parent table is updated or deleted, the value referenced in the foreign key table will be set to NULL.

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