改进model类order方法

添加json类型支持 支持json字段查询例如 $map['user$.name'] = 'thinkphp'
escapeString方法采用PDO::quote方法

library/think/db/driver/sqlsrv.php

@@ -100,6 +100,16 @@ class Sqlsrv extends Driver
      */
     protected function parseOrder($order)
     {
+        $array = [];
+        foreach ($order as $key => $val) {
+            if (is_numeric($key)) {
+                $array[] = $this->parseKey($val);
+            } else {
+                $sort    = in_array(strtolower(trim($val)), ['asc', 'desc']) ? ' ' . $val : '';
+                $array[] = $this->parseKey($key) . ' ' . $sort;
+            }
+        }
+        $order = implode(',', $array);
         return !empty($order) ? ' ORDER BY ' . $order : ' ORDER BY rand()';
     }