You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: spanner_drop_foreign_key_constraint_delete_cascade.go
    path of file: ./repos/golang-samples/spanner/spanner_snippets/spanner
    
    the code of the file until where you have to start completion: // Copyright 2023 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by
    
func dropForeignKeyDeleteCascade(w io.Writer, db string) error {
	// db := "projects/my-project/instances/my-instance/databases/my-database"
	ctx := context.Background()
	adminClient, err := database.NewDatabaseAdminClient(ctx)
	if err != nil {
		return err
	}
	defer adminClient.Close()

	// List of DDL statements to be applied to the database.
	// Alter the ShoppingCarts to drop foreign key constraint on CustomerName column of parent table.
	ddl := []string{
		"ALTER TABLE ShoppingCarts DROP CONSTRAINT FKShoppingCartsCustomerName",
	}
	op, err := adminClient.UpdateDatabaseDdl(ctx, &adminpb.UpdateDatabaseDdlRequest{
		Database:   db,
		Statements: ddl,
	})
	if err != nil {
		return err
	}
	// Wait for the UpdateDatabaseDdl operation to finish.
	if err := op.Wait(ctx); err != nil {
		return fmt.Errorf("waiting for operation to complete failed: %w", err)
	}
	fmt.Fprintf(w, "Altered ShoppingCarts table to drop FKShoppingCartsCustomerName foreign key constraint on database %v.\n", db)
	return err
}