Creating a Foreign Key

Create a foreign key to constrain a column or columns based on column values in another table.

Prerequisites

Before you can create a foreign key, be sure that the data server containing the table for which you are creating a foreign key is running, and you created and established a connection to the data server.

In the Databases folder in Enterprise Explorer, under the database connection profile, expand the navigation tree for the appropriate database and schema owner.

Database	Steps
From an ASE connection profile	Expand the Databases folder. Expand the tree for a database and then the tree for the appropriate schema owner.
From a SQL Anywhere or Sybase IQ connection profile	Expand the tree for a database. Expand the Schemas folder and then the tree for the appropriate schema owner.

Expand the Tables folder.
Right-click the table, and select New > Foreign Key .

Specify properties for the new foreign key.

Field	Description
Foreign Key Name	Enter a name for the foreign key in the text field, or leave the field blank for an auto-generated name.
Database	Choose a database for this data server.
Owner	Choose an owner for this data server.
Table	(Optional) Enter a filter expression for the tables to be displayed in the list of available primary tables. For example, * lists all tables for the specified database and owner combination.
Available Primary Tables	Highlight the table that you want this foreign key to reference.
Primary Key/Unique Constraints	Highlight the unique or primary key constraint in the primary table that this foreign key references.

Click Next, and specify column mappings for the foreign key.

Field	Description
Columns Mapping	Highlight the column or columns that you want subject to the foreign key constraint.
Match Full	Specify the constraint conditions on the values of the referencing columns. If all values in the referencing columns of a referencing row are: Null – the referential integrity condition is true. Non-null – the referential integrity condition is true if there is a referenced row where each corresponding column is equal in the referenced table. The referential integrity condition is false when: All values are non-null and not equal, or Some of the values in the referencing columns of a referencing row are non-null values, while others are null.
Preview	Displays the DDL for creating the foreign key.

Field

Description

Columns Mapping

Highlight the column or columns that you want subject to the foreign key constraint.

Match Full

Specify the constraint conditions on the values of the referencing columns. If all values in the referencing columns of a referencing row are:

Null – the referential integrity condition is true.
Non-null – the referential integrity condition is true if there is a referenced row where each corresponding column is equal in the referenced table.

The referential integrity condition is false when:

All values are non-null and not equal, or
Some of the values in the referencing columns of a referencing row are non-null values, while others are null.

Preview

Displays the DDL for creating the foreign key.

Click Next, and specify save and execution properties for the foreign key.

Field	Description
Generate Script	Generate DDL for the foreign key.
Enter or Select the Parent Folder	Specify an existing project or create a new project in which to save the DDL.
File Name	Enter the name of the file in which to store the DDL.
Execute Immediately	Execute the DDL immediately. If you do not select this option, you must complete execution of the DDL later to create the foreign key.
Open in Editor After Creation	Create the foreign key and open it in the Table Schema Editor.

Click Finish to create the foreign key.