ups

MysqliDb.php

@@ -215,6 +215,48 @@ class MysqliDb
         return $this->_dynamicBindResults($stmt);
     }
 
+    /**
+     * Pass in an array of subqueries for union query construction.
+     *
+     * @param array $objects Contains a user-provided array of subqueries
+     * @param $type 'ALL', 'DISTINCT', null.
+     *
+     * @return array Contains the returned rows from the query.
+     */
+    public function union ($objects, $type = null)
+    {
+        $allowedTypes = array('ALL', 'DISTINCT');
+        $type = strtoupper (trim ($type));
+
+        if ($type && !in_array ($type, $allowedTypes))
+            die ('Wrong UNION type: '.$type);
+
+        if (!is_array ($objects))
+            return;
+
+        $this->_query = "";
+        $i = 0;
+        foreach ($objects as $obj) {
+            if (!is_object ($obj))
+                continue;
+
+            if ($i++ != 0)
+                $this->_query .= " UNION {$type} ";
+
+            $subQuery = $obj->getSubQuery();
+            $this->_query .= "(" . $subQuery['query'] . ")";
+            foreach ($subQuery['params'] as $v)
+                $this->_bindParam ($v);
+        }
+        $stmt = $this->_buildQuery (null);
+        $stmt->execute();
+        $this->_stmtError = $stmt->error;
+        $this->reset();
+
+        return $this->_dynamicBindResults($stmt);
+    }
+
+
     /**
      *
      * @param string $query   Contains a user-provided select query.

readme.md

@@ -260,6 +260,21 @@ $data = Array (
 $id = $db->insert ("products", $data);
 // Gives INSERT INTO PRODUCTS (productName, userId, lastUpdated) values ("test product", (SELECT name FROM users WHERE id = 6), NOW());
 ```
+UNION queries
+```php
+$common = $db->subQuery();
+$common->where ("agentId", 10);
+
+$customers = $common->copy();
+$customers->get ("customers");
+
+$users = $common->copy();
+$users->get ("users");
+
+$db->orderBy ("lastModified");
+$res = $db->union (Array ($customers, $users, $companies), "ALL");
+GIVES (SELECT * FROM customers WHERE agentId = 10 ) UNION ALL (SELECT * FROM users WHERE agentId = 10 ) ORDER BY lastModified DESC
+```
 ### Helper commands
 Reconnect in case mysql connection died
 ```php