add MAX and MIN to functionbuilder

Signed-off-by: Robin Appelman <robin@icewind.nl>

lib/private/DB/QueryBuilder/FunctionBuilder/FunctionBuilder.php

@@ -76,4 +76,12 @@ class FunctionBuilder implements IFunctionBuilder {
 		$alias = $alias ? (' AS ' . $this->helper->quoteColumnName($alias)) : '';
 		return new QueryFunction('COUNT(' . $this->helper->quoteColumnName($count) . ')' . $alias);
 	}
+
+	public function max($field) {
+		return new QueryFunction('MAX(' . $this->helper->quoteColumnName($field) . ')');
+	}
+
+	public function min($field) {
+		return new QueryFunction('MIN(' . $this->helper->quoteColumnName($field) . ')');
+	}
 }

lib/public/DB/QueryBuilder/IFunctionBuilder.php

@@ -105,4 +105,24 @@ interface IFunctionBuilder {
 	 * @since 14.0.0
 	 */
 	public function count($count, $alias = '');
+
+	/**
+	 * Takes the maximum of all rows in a column
+	 *
+	 * @param mixed $field the column to maximum
+	 *
+	 * @return IQueryFunction
+	 * @since 18.0.0
+	 */
+	public function max($field);
+
+	/**
+	 * Takes the minimum of all rows in a column
+	 *
+	 * @param mixed $field the column to minimum
+	 *
+	 * @return IQueryFunction
+	 * @since 18.0.0
+	 */
+	public function min($field);
 }

tests/lib/DB/QueryBuilder/FunctionBuilderTest.php

@@ -120,4 +120,82 @@ class FunctionBuilderTest extends TestCase {
 
 		$this->assertGreaterThan(1, $query->execute()->fetchColumn());
 	}
+
+	private function setUpMinMax($value) {
+		$query = $this->connection->getQueryBuilder();
+
+		$query->insert('appconfig')
+			->values([
+				'appid' => $query->createNamedParameter('minmax'),
+				'configkey' => $query->createNamedParameter(uniqid()),
+				'configvalue' => $query->createNamedParameter((string)$value),
+			]);
+		$query->execute();
+	}
+
+	private function clearMinMax() {
+		$query = $this->connection->getQueryBuilder();
+
+		$query->delete('appconfig')
+			->where($query->expr()->eq('appid', $query->createNamedParameter('minmax')));
+		$query->execute();
+	}
+
+	public function testMaxEmpty() {
+		$this->clearMinMax();
+
+		$query = $this->connection->getQueryBuilder();
+
+		$query->select($query->func()->max($query->expr()->castColumn('configvalue', IQueryBuilder::PARAM_INT)));
+		$query->from('appconfig')
+			->where($query->expr()->eq('appid', $query->createNamedParameter('minmax')))
+			->setMaxResults(1);
+
+		$this->assertEquals(null, $query->execute()->fetchColumn());
+	}
+
+	public function testMinEmpty() {
+		$this->clearMinMax();
+
+		$query = $this->connection->getQueryBuilder();
+
+		$query->select($query->func()->min($query->expr()->castColumn('configvalue', IQueryBuilder::PARAM_INT)));
+		$query->from('appconfig')
+			->where($query->expr()->eq('appid', $query->createNamedParameter('minmax')))
+			->setMaxResults(1);
+
+		$this->assertEquals(null, $query->execute()->fetchColumn());
+	}
+
+	public function testMax() {
+		$this->clearMinMax();
+		$this->setUpMinMax(10);
+		$this->setUpMinMax(11);
+		$this->setUpMinMax(20);
+
+		$query = $this->connection->getQueryBuilder();
+
+		$query->select($query->func()->max($query->expr()->castColumn('configvalue', IQueryBuilder::PARAM_INT)));
+		$query->from('appconfig')
+			->where($query->expr()->eq('appid', $query->createNamedParameter('minmax')))
+			->setMaxResults(1);
+
+		$this->assertEquals(20, $query->execute()->fetchColumn());
+	}
+
+	public function testMin() {
+		$this->clearMinMax();
+		$this->setUpMinMax(10);
+		$this->setUpMinMax(11);
+		$this->setUpMinMax(20);
+
+		$query = $this->connection->getQueryBuilder();
+
+		$query->select($query->func()->min($query->expr()->castColumn('configvalue', IQueryBuilder::PARAM_INT)));
+		$query->from('appconfig')
+			->where($query->expr()->eq('appid', $query->createNamedParameter('minmax')))
+			->setMaxResults(1);
+
+		$this->assertEquals(10, $query->execute()->fetchColumn());
+	}
 }