select * from t1 ;

select * from t1 where age > 20;

select * from t1 where name like '李%';

select * from t1 where xh <45;

select * from t1 where age > 20;

select * from t1 where age+10>30;

select * from t1 where substr(name,1,1)='李';

select * from t1 where name like '李%';

select * from emp where to_char(hiredate,'yyyymm') >= '198210' and to_char(hiredate,'yyyymm') <='199909';create index ind_hiredate on emp(hiredate);

select * from emp where hiredate <= to_date('19990901','yyyymmdd') and hiredate >= to_date('19821001','yyyymmdd');