*
   * <p>Being reflexive, antisymmetric and transitive, the {@code encloses} relation defines a
   * <i>partial order</i> over ranges. There exists a unique {@linkplain Range#all maximal} range
   * according to this relation, and also numerous {@linkplain #isEmpty minimal} ranges. Enclosure
   * also implies {@linkplain #isConnected connectedness}.
   */

# SQL (Relational) Databases { #sql-relational-databases }

**FastAPI** doesn't require you to use a SQL (relational) database. But you can use **any database** that you want.

Here we'll see an example using <a href="https://sqlmodel.tiangolo.com/" class="external-link" target="_blank">SQLModel</a>.

		return ns.TablePrefix + str
	}

	if ns.SingularTable {
		return ns.TablePrefix + ns.toDBName(str)
	}
	return ns.TablePrefix + inflection.Plural(ns.toDBName(str))
}

// RelationshipFKName generate fk name for relation
func (ns NamingStrategy) RelationshipFKName(rel Relationship) string {
	return ns.formatName("fk", rel.Schema.Table, ns.toDBName(rel.Name))
}

// CheckerName generate checker name

	t := tag.Get("gorm")
	if strings.Contains(t, value) {
		return tag
	}
	return reflect.StructTag(fmt.Sprintf(`gorm:"%s;%s"`, value, t))
}

// GetRelationsValues get relations's values from a reflect value
func GetRelationsValues(ctx context.Context, reflectValue reflect.Value, rels []*Relationship) (reflectResults reflect.Value) {
	for _, rel := range rels {

    * Cookies, etc.

Plus all the security features from Starlette (including **session cookies**).

All built as reusable tools and components that are easy to integrate with your systems, data stores, relational and NoSQL databases, etc.

### Dependency Injection { #dependency-injection }

        }
        return list;
    }

    /**
     * Filter out whitelisted projects with a big twist:
     * Assume we have all projects {@code a, b, c} while active are {@code a, c} and relation among all projects
     * is {@code a -> b -> c}. This method handles well the case for transitive list. But, for non-transitive we need

import com.google.common.cache.TestingCacheLoaders.IncrementingLoader;
import com.google.common.testing.FakeTicker;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;

/**
 * Tests relating to automatic cache refreshing.
 *
 * @author Charles Fry
 */
@NullUnmarked
public class CacheRefreshTest extends TestCase {
  public void testAutoRefresh() {
    FakeTicker ticker = new FakeTicker();

You will see examples of this in the next chapters, about relational and NoSQL databases, security, etc.

## **FastAPI** compatibility { #fastapi-compatibility }

The simplicity of the dependency injection system makes **FastAPI** compatible with:

* all the relational databases
* NoSQL databases
* external packages
* external APIs
* authentication and authorization systems

     * </ul>
     * @throws DuplicateProjectException if any projects are duplicated by id
     */
    // MAVENAPI FIXME: the DAG used is NOT only used to represent the dependency relation,
    // but also for <parent>, <build><plugin>, <reports>. We need multiple DAG's
    // since a DAG can only handle 1 type of relationship properly.
    // Use case:  This is detected as a cycle:

Así que usamos un import relativo con `..` para las dependencias:

{* ../../docs_src/bigger_applications/app_an_py39/routers/items.py hl[3] title["app/routers/items.py"] *}

#### Cómo funcionan los imports relativos { #how-relative-imports-work }

/// tip | Consejo

Si sabes perfectamente cómo funcionan los imports, continúa a la siguiente sección.

///

Un solo punto `.`, como en:

```Python