Oracle 部门员工查询

CREATE TABLE dept(  
deptno INT PRIMARY KEY,
dname VARCHAR(20),
loc VARCHAR(20)   
);  
CREATE TABLE emp(
empno INT PRIMARY KEY,
ename VARCHAR(20) NOT NULL,    
job VARCHAR(20) CHECK (job IN('CLERK','SALESMAN','MANAGER','ANALYST')),
mgp INT,  
hiredate DATE ,
sal DECIMAL(10,2),
comm DECIMAL(10,2),  
deptno INT,  
CONSTRAINT pk_we FOREIGN KEY (deptno) REFERENCES dept (deptno)  
)

插入数据：

INSERT INTO dept VALUES (10,'ACCOUNTING','NEWTORK');  
INSERT INTO dept VALUES (20,'RESEARCH','DALLAS');  
INSERT INTO dept VALUES (30,'SALES','CHICAGO');  
INSERT INTO dept VALUES (40,'OPERATIONS','BOSTON');    
select * from dept
insert into emp values(7369,'SMITH','CLERK',7902,'1980-12-17',1640,NULL,20);
insert into emp values(7499,'ALLEN','SALESMAN',7698,'1981-2-20',11400,300,30);
insert into empvalues(7521,'WARD','SALESMAN',7698,'1981-2-22',5200,500,30);
insert into empvalues(7566,'JOENS','MANAGER',7839,'1981-4-2',7015,NULL,20);
insert into emp values(7654,'MARTIN','SALESMAN',7698,'1981-9-28',5200,1400,30);
insert into empvalues(7698,'BLAKE','MANAGER',7839,'1981-5-1',5900,NULL,30);
insert into empvalues(7782,'CLARK','MANAGER',7839,'1981-6-9',2470,NULL,10);
insert into emp values(7788,'SCOTT','ANALYST',7566,'1987-4-19',3040,NULL,20);

  select a.ENAME  from  emp a
             where exists(select * from  dept b where b.deptno=a.deptno and b.deptno=10);