Most of these comments don't seem to cover what you're asking for, which was building the schema visually. SQLEditor (https://www.malcolmhardie.com/sqleditor/

Most of these comments don't seem to cover what you're asking for, which was building the schema visually. SQLEditor (https://www.malcolmhardie.com/sqleditor/ https://www.malcolmhardie.com/sqleditor/) is quite good if you're on OS X. It'll generate entire schema or migration since last save.