This is personal study note Copyright and original reference: https://www.youtube.com/watch?v=2cplRFxGC9o&list=PLuHgQVnccGMAG1O1BRZCT3wkD_aPmPylq ================================================================================ Splitted tables ================================================================================ After join, state as if it's before split ================================================================================ When you create "new table" by using data which is in A and B, use "INNER JOIN" table_A INNER JOIN table_B (much used) ================================================================================ table_A LEFT JOIN table_B (much used) ================================================================================ table_A FULL OUTER JOIN table_B (not much used)