增
###直接插入数据 insert into t1(id,name,tel) values ('1','linux','13812341234');
INSERT INTO Employee1 VALUES(TO_DATE('19870211', 'YYYYMMDD'), '12365478', 'xs@126.com','男')
子查询插入
删
DELETE FROM Employee1 WHERE cEcode='0001'
改
##直接针对需要改动的点进行修改 update t1 set tel='15512345678' where tel='13812341234';
UPDATE Employee1 SET salary = salary +200
查
//查询多个条件 select from emp where comm is not null and sal >1500
SELECT * FROM SCJ WHERE SX IS NULL
exists替代in
#很多时候用 exists 代替 in 是一个好的选择: select num from a where num in(select num from b) #用下面的语句替换: select num from a where exists(select 1 from b where num=a.num)