Oracle学习

Oracle从入门到放弃

《收获，不止Oracle》

1.创建表

CREATE TABLE test(
  id number(20, 0) NOT NULL PRIMARY KEY,
  FieldAA varchar2(64),
  FieldAB varchar2(64),
  flag varchar(2)
);

insert into test values(1, 'a1','b1','D');
insert into test values(2, 'a2','b2','');
insert into test values(3, 'a3','b3','');
insert into test values(4, 'a4','b4','B');
insert into test values(5, 'a5','b5','');

2. <> 和 is not null

SELECT t.* FROM test t;

SELECT t.* FROM test t where t.flag <> 'D' or t.flag is null;

SELECT t.* FROM test t where t.flag <> 'D';

3.