Version 4.7.0

system/Db/Select.php

@@ -53,9 +53,14 @@ class _Select implements \Iterator, \Countable
 	protected $multiDimensional = FALSE;
 	
 	/**
-	 * @brief	If read/write sepration is enabled, SELECTs normally go to the read server - this flag will set thia query to use the write server
+	 * @brief	If read/write separation is enabled, SELECTs normally go to the read server - this flag will set this query to use the write server
 	 */
 	protected $useWriteServer = FALSE;
+
+	/**
+	 * @brief   Is this a union query? - this should only be set by the UNION method in \IPS\Db
+	 */
+	public $isUnion = FALSE;
 	
 	/**
 	 * Constuctor
@@ -224,7 +229,7 @@ class _Select implements \Iterator, \Countable
 			$this->query = str_replace( $matches[0], $key, $this->query );
 		}
 
-		if ( mb_strstr( $this->query, 'UNION' ) )
+		if ( $this->isUnion )
 		{
 			$this->query = str_replace( 'derivedTable', "derivedTable {$query}", $this->query );
 		}