Support for expressions

include.php

@@ -20,6 +20,7 @@
 include_once __DIR__ . '/src/Query/WriteToFile.php';
 include_once __DIR__ . '/src/Query/WhereInFile.php';
 include_once __DIR__ . '/src/Query/Query.php';
+include_once __DIR__ . '/src/Query/Expression.php';
 // Transport
 include_once __DIR__ . '/src/Transport/Http.php';
 include_once __DIR__ . '/src/Transport/CurlerRolling.php';

src/Client.php

@@ -6,6 +6,7 @@
 
 use ClickHouseDB\Exception\QueryException;
 use ClickHouseDB\Query\Degeneration;
+use ClickHouseDB\Query\Expression;
 use ClickHouseDB\Query\Degeneration\Bindings;
 use ClickHouseDB\Query\Degeneration\Conditions;
 use ClickHouseDB\Query\WhereInFile;
@@ -888,4 +889,16 @@ public function dropOldPartitions(string $table_name, int $days_ago, int $count_
 
         return $result;
     }
+
+    /**
+     * Build sql expression to be used "as is" in a query
+     *
+     * @param string $expression
+     *
+     * @return \ClickHouseDB\Query\Expression
+     */
+    public function expr($expression)
+    {
+        return new Expression($expression);
+    }
 }

src/Query/Expression.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace ClickHouseDB\Query;
+
+/**
+ * Query expression
+ *
+ * @package ClickHouseDB
+ */
+class Expression
+{
+    /**
+     * @var string
+     */
+    protected $expression = '';
+
+    /**
+     * Expression constructor.
+     *
+     * @param $expression
+     */
+    public function __construct($expression)
+    {
+        $this->expression = $expression;
+    }
+
+    /**
+     * @return string
+     */
+    public function __toString()
+    {
+        return $this->expression;
+    }
+}