New: BaseBuilder. Added methods that implement UNION.

system/Database/BaseBuilder.php

@@ -139,6 +139,34 @@ class BaseBuilder
 	 */
 	protected $QBWhereGroupCount = 0;
 
+	/**
+	 * Collection of union queries
+	 *
+	 * @var string[]
+	 */
+	protected $QBUnion = [];
+
+	/**
+	 * UNION ORDER BY data
+	 *
+	 * @var array
+	 */
+	protected $QBUnionOrderBy = [];
+
+	/**
+	 * QB UNION LIMIT data
+	 *
+	 * @var integer|boolean
+	 */
+	protected $QBUnionLimit = false;
+
+	/**
+	 * QB UNION OFFSET data
+	 *
+	 * @var integer|boolean
+	 */
+	protected $QBUnionOffset = false;
+
 	/**
 	 * Ignore data that cause certain
 	 * exceptions, for example in case of
@@ -1620,6 +1648,11 @@ public function orHaving($key, $value = null, bool $escape = null)
 	 */
 	public function orderBy(string $orderBy, string $direction = '', bool $escape = null)
 	{
+		if (count($this->QBUnion))
+		{
+			return $this->unionOrderBy($orderBy, $direction, $escape);
+		}
+
 		$direction = strtoupper(trim($direction));
 
 		if ($direction === 'RANDOM')
@@ -1686,6 +1719,11 @@ public function orderBy(string $orderBy, string $direction = '', bool $escape =
 	 */
 	public function limit(?int $value = null, ?int $offset = 0)
 	{
+		if (count($this->QBUnion))
+		{
+			return $this->unionLimit($value, $offset);
+		}
+
 		if (! is_null($value))
 		{
 			$this->QBLimit = $value;
@@ -3022,7 +3060,17 @@ protected function compileSelect($selectOverride = false): string
 		// LIMIT
 		if ($this->QBLimit)
 		{
-			return $this->_limit($sql . "\n");
+			$sql = $this->_limit($sql . "\n");
+		}
+
+		if (count($this->QBUnion))
+		{
+			if ($this->QBOrderBy || $this->QBLimit)
+			{
+				$sql = 'SELECT * FROM (' . $sql . ') as wrapper_alias';
+			}
+
+			$sql .= $this->compileUnion() . $this->compileUnionFilter();
 		}
 
 		return $sql;
@@ -3358,16 +3406,20 @@ protected function resetRun(array $qbResetItems)
 	protected function resetSelect()
 	{
 		$this->resetRun([
-			'QBSelect'   => [],
-			'QBJoin'     => [],
-			'QBWhere'    => [],
-			'QBGroupBy'  => [],
-			'QBHaving'   => [],
-			'QBOrderBy'  => [],
-			'QBNoEscape' => [],
-			'QBDistinct' => false,
-			'QBLimit'    => false,
-			'QBOffset'   => false,
+			'QBSelect'       => [],
+			'QBJoin'         => [],
+			'QBWhere'        => [],
+			'QBGroupBy'      => [],
+			'QBHaving'       => [],
+			'QBOrderBy'      => [],
+			'QBNoEscape'     => [],
+			'QBUnion'        => [],
+			'QBUnionOrderBy' => [],
+			'QBDistinct'     => false,
+			'QBLimit'        => false,
+			'QBOffset'       => false,
+			'QBUnionLimit'   => false,
+			'QBUnionOffset'  => false,
 		]);
 
 		if (! empty($this->db))
@@ -3492,6 +3544,157 @@ protected function setBind(string $key, $value = null, bool $escape = true): str
 		return $key . $count;
 	}
 
+	/**
+	 * Union queries
+	 *
+	 * @param Closure $closure Contains a query to combine
+	 *
+	 * @return static
+	 */
+	public function union(Closure $closure)
+	{
+		return $this->unionBuilder($closure);
+	}
+
+	/**
+	 * Union queries
+	 *
+	 * @param Closure $closure Contains a query to combine
+	 *
+	 * @return static
+	 */
+	public function unionAll(Closure $closure)
+	{
+		return $this->unionBuilder($closure, true);
+	}
+
+	/**
+	 * Union query builder
+	 *
+	 * @param Closure $closure Contains a query to combine
+	 * @param boolean $all     Using UNION ALL construction
+	 *
+	 * @return static
+	 */
+	protected function unionBuilder(Closure $closure, bool $all = false)
+	{
+		$builder = $closure($this->cleanClone());
+
+		if (! ($builder instanceof BaseBuilder))
+		{
+			throw new DatabaseException(
+				'BaseBuilder::union(). The closure must return an instance of the BaseBuilder class'
+			);
+		}
+
+		$sql = $builder->getCompiledSelect(false);
+
+		$all = $all ? 'ALL ' : '';
+
+		if (($builder->QBOrderBy || $builder->QBLimit || $builder->QBUnionOrderBy || $builder->QBUnionLimit)
+			&& strpos($sql, 'wrapper_alias UNION') === false)
+		{
+			$sql = 'SELECT * FROM (' . $sql . ') as wrapper_alias';
+		}
+
+		$builder->resetSelect();
+
+		$this->QBUnion[] = ' UNION ' . $all . $sql;
+
+		return $this;
+	}
+
+	/**
+	 * Compile UNION queries
+	 *
+	 * @return string
+	 */
+	protected function compileUnion() : string
+	{
+		return count($this->QBUnion) ? join('', $this->QBUnion) : '';
+	}
+
+	/**
+	 * UNION ORDER BY global
+	 *
+	 * @param string  $orderBy   Field
+	 * @param string  $direction ASC, DESC or RANDOM
+	 * @param boolean $escape    Escape
+	 *
+	 * @return $this
+	 */
+	protected function unionOrderBy(string $orderBy, string $direction = '', bool $escape = null)
+	{
+		$this->QBUnionOrderBy[] = [
+			$orderBy,
+			$direction,
+			$escape,
+		];
+
+		return $this;
+	}
+
+	/**
+	 * UNION LIMIT global
+	 *
+	 * @param integer|null $value  LIMIT value
+	 * @param integer|null $offset OFFSET value
+	 *
+	 * @return $this
+	 */
+	protected function unionLimit(?int $value = null, ?int $offset = 0)
+	{
+		if (! is_null($value))
+		{
+			$this->QBUnionLimit = $value;
+		}
+
+		return $this->unionOffset($offset);
+	}
+
+	/**
+	 * Sets the UNION OFFSET value
+	 *
+	 * @param integer $offset OFFSET value
+	 *
+	 * @return $this
+	 */
+	protected function unionOffset(int $offset)
+	{
+		if (! empty($offset))
+		{
+			$this->QBUnionOffset = (int) $offset;
+		}
+
+		return $this;
+	}
+
+	/**
+	 * Compile UNION Filter as ORDER BY and LIMIT
+	 *
+	 * @return string
+	 */
+	protected function compileUnionFilter() : string
+	{
+		$builder = $this->cleanClone();
+
+		foreach ($this->QBUnionOrderBy as $order)
+		{
+			$builder->orderBy(...$order);
+		}
+
+		$filter = $builder->compileOrderBy();
+
+		$builder->limit($this->QBUnionLimit, $this->QBUnionOffset);
+
+		if ($this->QBUnionLimit)
+		{
+			$filter = $builder->_limit($filter . "\n");
+		}
+
+		return $filter;
+	}
+
 	//--------------------------------------------------------------------
 
 	/**

system/Database/SQLSRV/Builder.php

@@ -651,7 +651,17 @@ protected function compileSelect($selectOverride = false): string
 		// LIMIT
 		if ($this->QBLimit)
 		{
-			return $sql = $this->_limit($sql . "\n");
+			$sql = $this->_limit($sql . "\n");
+		}
+
+		if ($this->QBUnion)
+		{
+			if ($this->QBOrderBy || $this->QBLimit)
+			{
+				$sql = 'SELECT * FROM (' . $sql . ') as wrapper_alias';
+			}
+
+			$sql .= $this->compileUnion() . $this->compileUnionFilter();
 		}
 
 		return $sql;