Query records in Table A but not in table B.

Query records in Table A but not in table B.

Software environment: 1. Windows NT4.0 + Oracle 8.0.4 2. Oracle installation path: C: \ orant Implementation Method: SQL> Create Table A (2 BM char (4), -- encoding 3 Mc varchar2 (20) -- name 4) 5/the table has been created. SQL> insert into a values ('20170301', '20160301'); SQL> INSERT INTO A values ('20160301', '20160301 '); SQL> insert into a values ('20170301', '20160301'); SQL> INSERT INTO A values ('20160301', '20160301 '); SQL> insert into a values ('20140901', '20160901'); SQL> Create Table B as select * from a where 1 = 2; the table has been created. SQL> insert into B values ('20170301', '20160301'); SQL> insert into B values ('20160301', '20160301 '); SQL> insert into B values ('20140901', '20160901'); SQL> insert into B values ('20160901', '20160901'); SQL> commit; completely submitted. SQL> select * From A; BM Mc ---- ------------------ 1111 11111112 11111113 11111114 11111115 1111sql> select * from B; BM Mc ---- -------------------- 1111 11111112 11111113 11111114 1111sql> select BM from a where not exists (select BM from B where. bm = B. BM); BM Mc ---- -------------------- 1115 1111