From 4a9110e120b105c0ad29d028c721c312f405f75a Mon Sep 17 00:00:00 2001
From: Shang Ning <jvyyuie@gmail.com>
Date: Tue, 29 Aug 2017 19:57:50 +0800
Subject: add NATURAL JOIN types to fix #5240

---
 system/database/DB_query_builder.php | 24 ++++++++++++++++++++----
 1 file changed, 20 insertions(+), 4 deletions(-)

(limited to 'system/database')

diff --git a/system/database/DB_query_builder.php b/system/database/DB_query_builder.php
index 102ff4ac0..98ba71dbc 100644
--- a/system/database/DB_query_builder.php
+++ b/system/database/DB_query_builder.php
@@ -525,20 +525,29 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 	 */
 	public function join($table, $cond, $type = '', $escape = NULL)
 	{
+		$natural_join = FALSE;
+
 		if ($type !== '')
 		{
 			$type = strtoupper(trim($type));
 
-			if ( ! in_array($type, array('LEFT', 'RIGHT', 'OUTER', 'INNER', 'LEFT OUTER', 'RIGHT OUTER'), TRUE))
+			if (in_array($type, array('LEFT', 'RIGHT', 'OUTER', 'INNER', 'LEFT OUTER', 'RIGHT OUTER'), TRUE))
 			{
-				$type = '';
+				$type .= ' ';
 			}
-			else
+			elseif (in_array($type, array('NATURAL', 'NATURAL LEFT', 'NATURAL RIGHT', 'NATURAL LEFT OUTER', 'NATURAL RIGHT OUTER'), TRUE))
 			{
 				$type .= ' ';
+				$natural_join = TRUE;
+			}
+			else
+			{
+				$type = '';
 			}
 		}
 
+
+
 		// Extract any aliases that might exist. We use this information
 		// in the protect_identifiers to know whether to add a table prefix
 		$this->_track_aliases($table);
@@ -594,7 +603,14 @@ abstract class CI_DB_query_builder extends CI_DB_driver {
 		}
 
 		// Assemble the JOIN statement
-		$this->qb_join[] = $join = $type.'JOIN '.$table.$cond;
+		if ($natural_join === FALSE)
+		{
+			$this->qb_join[] = $join = $type.'JOIN '.$table.$cond;
+		}
+		else
+		{
+			$this->qb_join[] = $join = $type.'JOIN '.$table;
+		}
 
 		if ($this->qb_caching === TRUE)
 		{
-- 
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