title: Add realtime database with android studio firebase
body: <pre><code>apply plugin: 'com.android.application'
  
  android 
  {
  
      compileSdkVersion 24
      buildToolsVersion "28.0.3"
      defaultConfig {
          applicationId "com.example.asus.salestrackingsystem"
          minSdkVersion 15
          targetSdkVersion 24
          versionCode 1
          versionName "1.0"
          testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
  
      compile fileTree(dir: 'libs', include: ['*.jar'])
      androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
          exclude group: 'com.android.support', module: 'support-annotations'
      })'
  
      compile 'com.android.support:design:25.3.1'
      compile 'com.android.support:appcompat-v7:24.2.1'
      compile 'com.google.firebase:firebase-auth:16.0.5'
      compile 'com.google.firebase:firebase-database:16.0.5'
      testCompile 'junit:junit:4.12'
  }
  
  
  
  apply plugin: 'com.google.gms.google-services'
  </code></pre>
  
  <p>but still cant success to add realtime database , firebase assistant keep asking to add the realtime database to your app . anyone can help me?</p>