oracle 学习笔记四

SELECT table1.column, table2.column

FROM table1

[CROSS JOIN table2] |

[NATURAL JOIN table2] |

[JOIN table2 USING (column_name)] |

[JOIN table2

ON(table1.column_name = table2.column_name)] |

[LEFT|RIGHT|FULL OUTER JOIN table2

ON (table1.column_name = table2.column_name)];

交叉连接 CROSS JOIN

oracle 8i中

select * from employees,departments;

oracle 9i中

select * from employees CROSS JOIN departments;

自然连接 NATURAL JOIN

oracle 8i

select * from emp e,dept d where e.deptno=d.deptno;

oracle 9i

select * from emp NATURAL JOIN dept;

select * from emp join dept using (deptno);

on子名

sql-1999

select * from emp;

select * from dept;

select e.ename,e.empno,d.dname,d.deptno

from emp e join dept d on(e.deptno=d.deptno);

三个表的内连接

select * from employees;

select * from location;

select * from departments;

oracle8i等值接连

select e.employee_id,e.first_name||e.last_name,d.department_id,d.department_name,l.loc,l.city

from employees e,departments d,location l where e.department_id=d.department_id and d.location_id=l.location_id;

sql-1999

select e.employee_id,e.first_name||e.last_name,d.department_id,d.department_name,l.loc,l.city

from employees e join departments d on(e.department_id=d.department_id) join location l on(d.location_id=l.location_id);

左外连接 LEFT OUTER JOIN 对连接条件中左边的表中的记录不加限制

oracle8i右外接连

select e.employee_id,e.first_name||e.last_name,d.department_id,d.department_name

from employees e, departments d where e.department_id=d.department_id(+);

sql-1999

select e.employee_id,e.first_name||e.last_name,d.department_id,d.department_name

from employees e left outer join departments d on(e.department_id=d.department_id);

右外连接 RIGHT OUTER JOIN 对连接条件中右边的表中的记录不加限制

oracle8i左外接连

select e.employee_id,e.first_name||e.last_name,d.department_id,d.department_name

from employees e, departments d where e.department_id(+)=d.department_id;

sql-1999

select e.employee_id,e.first_name||e.last_name,d.department_id,d.department_name

from employees e right outer join departments d on(e.department_id=d.department_id);

全外连接 Full outer Join 全外连接是对两个表中的记录都不加限制。

select e.employee_id,e.first_name||e.last_name,d.department_id,d.department_name

from employees e full outer join departments d on(e.department_id=d.department_id);