So please give me some help, to write a SQL query,

Watch a, b, c

Table a: id, name, date of work
Table B: id, name, the salary
Table C: id, name, domicile of origin

Query: a table, the people in the native place condition: working date is earlier than "2021/1/1" and not the name in table B,

Table is just a example, to facilitate description,

For the first time to CSDN, ask everybody to help you, with efficient statement as far as possible, if you can, write four tables?