This is personal study note Copyright and original reference: https://www.youtube.com/watch?v=Zn-cECPEORU&list=PLuHgQVnccGMAG1O1BRZCT3wkD_aPmPylq ================================================================================ ================================================================================ ================================================================================ Full join = left join + right join remove duplicate Many DB system doesn't support full outer join So you can use "union"