Foreign Keys

This section describes how to access information about foreign keys by retrieving the ForeignKeys schema collection.

Retrieving Foreign Key Information

To retrieve the ForeignKeys schema collection, call the GetSchema method of the CompositeConnection class. You can restrict foreign key information by the table name.

Access the results in the DataTable returned. The following example lists the foreign keys for the Products table.

C#

String connectionString = "Host=myHost;Domain=myDomain;DataSource=myDataSource;User=myUser;Password=myPassword";

using (CompositeConnection conn = new CompositeConnection(connectionString)) {

  conn.Open();

  DataTable databaseSchema = conn.GetSchema("ForeignKeys", new string[] {"Products"});

  foreach (DataRow row in databaseSchema.Rows) {

    Console.WriteLine(row["CONSTRAINT_NAME"]);

    Console.WriteLine(row["TABLE_NAME"]);

  }

}

VB.NET

Dim connectionString As String = "Host=myHost;Domain=myDomain;DataSource=myDataSource;User=myUser;Password=myPassword"

Using conn As New CompositeConnection(connectionString)

  conn.Open()

  Dim databaseSchema As DataTable = conn.GetSchema("ForeignKeys",  New String() {"Products"})

    For Each row As DataRow In databaseSchema.Rows

    Console.WriteLine(row("CONSTRAINT_NAME"))

    Console.WriteLine(row("TABLE_NAME"))

  Next

End Using

Columns Returned

The ForeignKeys schema collection returns the following information about the foreign keys in TDV.

Column Name	Data Type	Description
CONSTRAINT_CATALOG	System.String	The database containing the foreign key.
CONSTRAINT_SCHEMA	System.String	The schema containing the foreign key.
CONSTRAINT_NAME	System.String	The name of the foreign key.
CONSTRAINT_TYPE	System.String	Returns FOREIGN KEY.
TABLE_CATALOG	System.String	The database of the table containing the foreign key.
TABLE_SCHEMA	System.String	The schema of the table containing the foreign key.
TABLE_NAME	System.String	The name of the table containing the foreign key.
IS_DEFERRABLE	System.String	Whether the foreign key is deferrable. This value is YES or NO.
INITIALLY_DEFERRED	System.String	Whether the foreign is initially deferrable. This value is YES or NO.