Starting with Visual Studio 2017, the functionality of creating Database Projects has been integrated into the Visual Studio installation. There's no need to install the SSDT standalone installer for the core SSDT experience.
Now to create Analysis Services, Integration Services, or Reporting Services projects, you still need the SSDT standalone installer.
Install Analysis Services, Integration Services, and Reporting Services tools
To install Analysis Services, Integration Services, and Reporting Services project support, run the SSDT standalone installer.
The installer lists available Visual Studio instances to add SSDT tools. If Visual Studio isn't already installed, selecting Install a new SQL Server Data Tools instance installs SSDT with a minimal version of Visual Studio, but for the best experience, we recommend using SSDT with the latest version of Visual Studio
