### Criar um Engine { #create-an-engine }
Um `engine` SQLModel (por baixo dos panos, ele é na verdade um `engine` do SQLAlchemy) é o que **mantém as conexões** com o banco de dados.

Você teria **um único objeto `engine`** para todo o seu código se conectar ao mesmo banco de dados.

{* ../../docs_src/sql_databases/tutorial001_an_py310.py ln[14:18] hl[14:15,17:18] *}

          <defaultValue>true</defaultValue>
          <type>boolean</type>
          <description>Whether to send notifications on warning.</description>
        </field>
        <!-- TODO: Remove it after continuum alpha-3 release -->
        <field>
          <name>address</name>
          <version>4.0.0+</version>
          <type>String</type>
          <description>

        valueMap.put("script", normalizeScript(script));
        log(valueMap);
    }

    /**
     * Normalize script content for logging.
     * Replaces control characters and truncates if too long.
     * @param script The script content.
     * @return The normalized script content.
     */
    protected String normalizeScript(final String script) {
        if (script == null) {
            return "-";

      return delegate;
    }

    @Override
    public int size() {
      return delegate.size() + delta;
    }
  }

  @SuppressWarnings("JoinIterableIterator") // explicitly testing iterator overload, too
  public void testNoSpecialNullBehavior() {
    checkNoOutput(J, iterable);
    checkResult(J, iterable1, "1");
    checkResult(J, iterable12, "1-2");
    checkResult(J, iterable123, "1-2-3");

    CountingRemovalListener<Integer, Integer> removalListener = countingRemovalListener();
    IdentityLoader<Integer> loader = identityLoader();

    // Even numbers are free, odd are too expensive
    Weigher<Integer, Integer> evensOnly = (k, v) -> k % 2;

    LoadingCache<Integer, Integer> cache =
        CacheBuilder.newBuilder()
            .concurrencyLevel(1)
            .maximumWeight(0)

        ndrBuffer.readOctetArray(destData, 0, sourceData.length);

        assertEquals(sourceData.length, ndrBuffer.getIndex());
        assertEquals(sourceData.length, ndrBuffer.getLength()); // Length is updated on read too
        assertArrayEquals(sourceData, destData);

        // Read with offset and length
        ndrBuffer.setIndex(0);
        Arrays.fill(destData, (byte) 0x00); // Clear destData

        assertThrows(
            IllegalArgumentException.class, () -> checkArgument(false, "A %s C", (Object) null));
    assertThat(e).hasMessageThat().isEqualTo("A null C");
  }

  @J2ktIncompatible // TODO(b/319404022): Allow passing null array as varargs
  public void testCheckArgument_singleNullArray_failure() {
    IllegalArgumentException e =
        assertThrows(

        assertThrows(
            IllegalArgumentException.class, () -> checkArgument(false, "A %s C", (Object) null));
    assertThat(e).hasMessageThat().isEqualTo("A null C");
  }

  @J2ktIncompatible // TODO(b/319404022): Allow passing null array as varargs
  public void testCheckArgument_singleNullArray_failure() {
    IllegalArgumentException e =
        assertThrows(

import com.google.common.cache.LocalCache.Strength;
import com.google.common.testing.EqualsTester;
import junit.framework.TestCase;
import org.jspecify.annotations.NullUnmarked;

/**
 * Tests CacheBuilderSpec. TODO(user): tests of a few invalid input conditions, boundary
 * conditions.
 *
 * @author Adam Winer
 */
@NullUnmarked
public class CacheBuilderSpecTest extends TestCase {
  public void testParse_empty() {

	case sqlFnLower:
		return lowerCase(argVals[0])

	case sqlFnUpper:
		return upperCase(argVals[0])

	case sqlFnUTCNow:
		return handleUTCNow()

	case sqlFnToString, sqlFnToTimestamp:
		// TODO: implement
		fallthrough

	default:
		return nil, errNotImplemented
	}
}

func coalesce(args []*Value) (res *Value, err error) {
	for _, arg := range args {
		if arg.IsNull() {
			continue