How to add foreign keys to navicat model

Steps to add a foreign key in Navicat: Select the foreign key column and specify the reference table and reference field in the "Foreign Key" tab. Set delete and update operations: CASCADE, SET NULL, SET DEFAULT, or RESTRICT. Click OK to save the changes and Navicat will automatically execute the SQL statement to add the foreign key constraint.

Add foreign key in Navicat model

Foreign key is a kind of relational database to achieve data integrity constraint mechanism. The steps to add a foreign key in the Navicat model are as follows:

1. Select the foreign key column

• Right-click on the table where you want to add the foreign key and Select "Edit Table".
• In the Fields tab, select the column to be the foreign key.

2. Set foreign key properties

• In the Fields window, go to the Foreign Keys tab.
• Select the "Foreign Key" checkbox.
• In the "Referenced table" field, select the table that references the foreign key.
• In the "Reference Field" field, select the column in the table referenced by the foreign key.

3. Specify delete and update operations

• In the "Foreign Key" tab, select one of the following delete and update behaviors One:

  • ##CASCADE: When a record in the foreign key table is deleted or updated, the record that references the record is also deleted or updated.
  • SET NULL: When a record in the foreign key table is deleted, set the foreign key column of the record that refers to the record to NULL.
  • SET DEFAULT: When a record in the foreign key table is deleted, set the foreign key column of the record that refers to the record to its default value.
  • RESTRICT: When a record in the foreign key table is deleted or updated, the operation is rejected.

4. Apply changes

Click the OK button to save the changes.
• Navicat now automatically executes the necessary database ALTER statements to add foreign key constraints.

Note:

The data type of the foreign key column must be compatible with the data type of the referenced column.
• The referenced column must have a unique constraint or a primary key constraint.
• You can add foreign keys directly using SQL statements. In Navicat, right-click the table in the model and select "Edit SQL" to view or edit the SQL statement.

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