Question

I’m a newbie, just learning SQL and have this question: I have two tables with the same columns. Some registers are in the two tables but others only are in one of the tables. To illustrate, suppose table A = (1,2,3,4), table B=(3,4,5,6), numbers are registers. I need to select all registers in table B if they are not in table A, that is result=(5,6). What query should I use? Maybe a join. Thanks.

Answer 1

Select register from TABLE_B b
Where not exists (Select register from TABLE_A a where a.register = b.register)

I assumed you have a column named register in TABLE_A and TABLE_B