How to set constraints in navicat

Setting constraints in Navicat ensures data integrity by specifying data types, ranges, and rules to limit table data. The steps include: Open the table designer. Select the column and fill in the constraint type, value, and settings. Navicat provides several constraint types, including NOT NULL, UNIQUE, PRIMARY KEY, FOREIGN KEY, and CHECK. You can set constraint options such as primary key increment, foreign key references, and custom expressions. save Changes.

How to set constraints in Navicat

Setting constraints in Navicat can ensure the data integrity in the database table . Constraints can specify data types, ranges, or other rules to limit or control the data in a table. The following steps describe how to set constraints in Navicat:

1. Open Navicat and select the table

• Open Navicat and connect to the database you want to edit.
• In the left navigator, find and right-click the table you want to edit.

2. Select "Table Designer"

• Select "Table Designer" from the right-click menu.

3. Add column constraints

• In the "Table Designer", select the column to which you want to add constraints.
• In the Column Properties section, look for the Constraints tab.
• Fill in the constraint type, value and settings as needed.

4. Available constraint types

Navicat provides various constraint types, including:

• ##NOT NULL: Ensure that the column does not allow null values.
• UNIQUE: Ensures that the values ​​in this column are unique.
• PRIMARY KEY: Specify that this column is the primary key of the table, it must be unique and non-null.
• FOREIGN KEY: Establish a relationship between this column and the primary key in another table.
• CHECK: Use a custom expression to verify the value in this column.

5. Set constraint options

For some constraint types, you can set other options, for example:

• Primary key: After setting the primary key, you can specify whether to allow auto-increment.
• Foreign key: Specify the table and column referenced by the foreign key.
• Check: Specify a custom expression to check.

6. Save changes

Once all necessary constraints are set, click the Save button.

Notes on adding constraints:

Make sure the constraints are compatible with the data type and structure in the table.
• Consider the impact of constraints on application performance and data maintenance.
• Before modifying constraints, consider the existing data in the table.

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