selecttable1.column, table2.column
fromtable1
[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)];
交叉連線 cross join
oracle 8i中
select * from employees,departments;
oracle 9i中
select * from employees cross join departments;
自然連線 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);
三個表的內連線
select * from employees;
select * from location;
select * from departments;
oracle8i等值接連
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);
左外連線 left outer join 對連線條件中左邊的表中的記錄不加限制
oracle8i右外接連
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);
右外連線 right outer join 對連線條件中右邊的表中的記錄不加限制
oracle8i左外接連
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);
全外連線 full outer join 全外連線是對兩個表中的記錄都不加限制。
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);
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