1.端口
Oracle—-1521 SqlServer—1433 MySQL—–3306 postgreSQL—–5432
2.自动生成主键
Oracle—-sequence—select seq.nextval from dual;select seq.currval from dual;
SqlServer—identity(1,1)–studentId int primary key identity(1,1),
MySQL—–auto_increment —-studentId int primary key auto_increment,
postgreSQL—–sequence——–select currval(‘seq’);select nextval(‘seq’)
3.分页查询11-15
Oracle—-select * from (select rownum rm,e.* from emp e) where rownum =5 and rm =11
SqlServer—select top 5 * from student where sno not in (select top 10 sno from student);
MySQL—select * from student limit 10,5;
postgreSQL—select * from student limit 5 offset 10
