From e3ed50296f79ce177ca3301176dc2cf1a3cd8799 Mon Sep 17 00:00:00 2001
From: Tim Otten <totten@civicrm.org>
Date: Tue, 29 Oct 2019 17:20:46 -0700
Subject: [PATCH] CRM_Upgrade_Incremental_Base - Add helper dropTableIfEmpty()

---
 CRM/Upgrade/Incremental/Base.php | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/CRM/Upgrade/Incremental/Base.php b/CRM/Upgrade/Incremental/Base.php
index 48d8ed49ff..1f72699fea 100644
--- a/CRM/Upgrade/Incremental/Base.php
+++ b/CRM/Upgrade/Incremental/Base.php
@@ -279,6 +279,26 @@ class CRM_Upgrade_Incremental_Base {
     return TRUE;
   }
 
+  /**
+   * Drop a table... but only if it's empty.
+   *
+   * @param CRM_Queue_TaskContext $ctx
+   * @param string $table
+   * @return bool
+   */
+  public static function dropTableIfEmpty($ctx, $table) {
+    if (CRM_Core_DAO::checkTableExists($table)) {
+      if (!CRM_Core_DAO::checkTableHasData($table)) {
+        CRM_Core_BAO_SchemaHandler::dropTable($table);
+      }
+      else {
+        $ctx->log->warning("dropTableIfEmpty($table): Found data. Preserved table.");
+      }
+    }
+
+    return TRUE;
+  }
+
   /**
    * Rebuild Multilingual Schema.
    * @param CRM_Queue_TaskContext $ctx
-- 
2.25.1