您好，

您可以使用为其他Web应用程序创建的现有数据库。在Azure门户中，您可以选择在创建新的webapp时选择"使用现有"数据库，如下所示

I created a web app ( example: sampleWebapp1).

Selected the  'Mysql in app' option and created database ( example: testdb ) in 'PhpMyadmin'. 

is it possible to access the database(testdb) by another web app or from local machine ?

Hello,

You may use the existing database created for another webapp. In Azure portal, you can have the option to select 'Use Existing' database when you create a new webapp as below