src/QueryBuilder.php
public function groupBy( $expressions /* expressions ... */ )  {
		$expressions = is_array( $expressions ) ? $expressions : func_get_args();

		$this->modifierBuilder->groupBy( $expressions );
		return $this;
	}
public function groupBy( $expressions /* expressions ... */ )  {
		$expressions = is_array( $expressions ) ? $expressions : func_get_args();

		$this->modifierBuilder->groupBy( $expressions );
		return $this;
	}
public function groupBy ( $ expressions /* expressions ... */ ) { $ expressions = is_array ( $ expressions ) ? $ expressions : func_get_args ( ) ; $ this -> modifierBuilder -> groupBy ( $ expressions ) ; return $ this ; }
Sets the GROUP BY modifier.

@param string|string[] $expressions
@return self
@throws InvalidArgumentException
Sets the GROUP BY modifier .