fix mysql db test bug

Former-commit-id: bd5f9aba465516029e510dd5b2ca5d1ce4a17052

cpp/CHANGELOG.md

@@ -22,6 +22,7 @@ Please mark all change in change log and use the ticket from JIRA.
 - MS-461 - Mysql meta unittest failed
 - MS-462 - Run milvus server twices, should display error
 - MS-463 - Search timeout
+- MS-467 - mysql db test failed
 
 ## Improvement
 - MS-327 - Clean code for milvus

cpp/unittest/db/utils.cpp

@@ -124,7 +124,12 @@ zilliz::milvus::engine::DBMetaOptions MySQLTest::getDBMetaOptions() {
 zilliz::milvus::engine::Options MySQLDBTest::GetOptions() {
     auto options = engine::OptionsFactory::Build();
     options.meta.path = "/tmp/milvus_test";
-    options.meta.backend_uri = "mysql://root:Fantast1c@192.168.1.194:3306/";
+    options.meta.backend_uri = DBTestEnvironment::getURI();
+
+    if(options.meta.backend_uri.empty()) {
+        options.meta.backend_uri = "mysql://root:Fantast1c@192.168.1.194:3306/";
+    }
+
     return options;
 }