CREATE TABLE emp(empno INT,ename VARCHAR(50),job VARCHAR(50),mgr INT,hiredate DATE,sal DECIMAL(7,2),comm DECIMAL(7,2),deptno INT ) ;INSERT INTO emp VALUES(7369,'SMITH','CLERK',7902,'1980-12-17',800,NULL,20); INSERT INTO emp VALUES(7499,'ALLEN','SALESMAN',7698,'1981-02-20',1600,300,30); INSERT INTO emp VALUES(7521,'WARD','SALESMAN',7698,'1981-02-22',1250,500,30); INSERT INTO emp VALUES(7566,'JONES'...
CREATE TABLE emp(empno INT,ename VARCHAR(50),job VARCHAR(50),mgr INT,hiredate DATE,sal DECIMAL(7,2),comm DECIMAL(7,2),deptno INT ) ;INSERT INTO emp VALUES(7369,'SMITH','CLERK',7902,'1980-12-17',800,NULL,20); INSERT INTO emp VALUES(7499,'ALLEN','SALESMAN',7698,'1981-02-20',1600,300,30); INSERT INTO emp VALUES(7521,'WARD','SALESMAN',7698,'1981-02-22',1250,500,30); INSERT INTO emp VALUES(7566,'JONES'...
1.建表create table Student (ID int, Name varchar(20),Age int ); 2.增insert into Student values(1,"April",21); insert into Student values(2,"Harris",22); insert into Student values(3,"Dave",19); 3.删delete from Student where Name='Dave'; 删除Name=“Dave”的行。如果没有where子句，会删除整个表中的数据。 4.改update Student set Age = 20 where ID=1; 修改ID=1的行，将年龄修改为20。如果没有where子...