在ORACLE9i之前，oracle语法基础是SQL/86标准，9i及之后的版本中支持SQL/92标准。
基表信息：products、purchases和product_types
SQL> select * from products;
PRODUCT_ID PRODUCT_TYPE_ID NAME DESCRIPTION PRICE
---------- --------------- ------------------------------ -------------------------------------------------- ----------
1 1 Modern Science A description of modern science 19.95
2 1 Chemistry Introduction to Chemistry 30
3 2 Supernova A star explodes 25.99
4 2 Tank War Action movie about a future war 13.95
5 2 Z Files Series on mysterious activities 49.99
6 2 2412: The Return Aliens return 14.95
7 3 Space Force 9 Adventures of heroes 13.49
8 3 From Another Planet Alien from another planet lands on Earth 12.99
9 4 Classical Music The best classical music 10.99
10 4 Pop 3 The best popular music 15.99
11 4 Creative Yell Debut album 14.99
12 My Front Line Their greatest hits 13.49
已选择12行。
SQL> select * from product_types;
PRODUCT_TYPE_ID NAME
--------------- ----------
1 Book
5 Magazine
4 CD
3 DVD
2 Video
100 test
已选择6行。
SQL> SELECT * FROM PURCHASES;
PRODUCT_ID CUSTOMER_ID QUANTITY
---------- ----------- ----------
1 2 2
3 3 1
2 3 1
1 3 1
2 2 1
SQL>
1、使用Oracle连接语法(SQL/86版)
SQL> select p.name,pt.name type from products p,product_types pt where p.product_type_id=pt.product_type_id order by p.name; NAME TYPE ------------------------------ ---------- 2412: The Return Video Chemistry Book Classical Music CD Creative Yell CD From Another Planet DVD Modern Science Book Pop 3 CD Space Force 9 DVD Supernova Video Tank War Video Z Files Video 已选择11行。
2、使用SQL/92引入INNER JOIN和ON重写上面的查询
SQL> select p.name,pt.name type from products p inner join product_types pt on p.product_type_id=pt.product_type_id order by p.name; NAME TYPE ------------------------------ ---------- 2412: The Return Video Chemistry Book Classical Music CD Creative Yell CD From Another Planet DVD Modern Science Book Pop 3 CD Space Force 9 DVD Supernova Video Tank War Video Z Files Video 已选择11行。
3、SQL/92使用using代替on进行简化连接：
SQL> select p.name,pt.name type from products p inner join product_types pt using (product_type_id); NAME TYPE ------------------------------ ---------- Modern Science Book Chemistry Book Z Files Video Tank War Video Supernova Video 2412: The Return Video Space Force 9 DVD From Another Planet DVD Classical Music CD Pop 3 CD Creative Yell CD 已选择11行。 SQL>
------------USING子句不能使用表别名，否则报错：
SQL> select p.name,pt.name type,product_type_id from products p inner join product_types pt using (p.product_type_id);
select p.name,pt.name type,product_type_id from products p inner join product_types pt using (p.product_type_id)
*
第 1 行出现错误:
ORA-01748: 此处只允许简单的列名
4、同上，如果希望在查看product_type_id的值，则在SELECT子句中只能指定该列名，不能再在该列名前加表的别名
SQL> select p.name,pt.name type,product_type_id from products p inner join product_types pt using (product_type_id);
NAME TYPE PRODUCT_TYPE_ID
------------------------------ ---------- ---------------
Modern Science Book 1
Chemistry Book 1
Z Files Video 2
Tank War Video 2
Supernova Video 2
2412: The Return Video 2
Space Force 9 DVD 3
From Another Planet DVD 3
Classical Music CD 4
Pop 3 CD 4
Creative Yell CD 4
已选择11行。
SQL> select p.name,pt.name type,pt.product_type_id from products p inner join product_types pt using (product_type_id);
select p.name,pt.name type,pt.product_type_id from products p inner join product_types pt using (product_type_id)
*
第 1 行出现错误:
ORA-25154: USING 子句的列部分不能有限定词
SQL>
5、使用SQL/92执行多表内连接
SQL/86: SQL> select c.first_name,c.last_name,p.name as product,pt.name as type from customers c,purchases pr,products p,product_types pt 2 where c.customer_id=pr.customer_id and p.product_id=pr.product_id and p.product_type_id=pt.product_type_id order by p.name; FIRST_NAME LAST_NAME PRODUCT TYPE ---------- ---------- ------------------------------ ---------- Cynthis Green Chemistry Book Steve White Chemistry Book Cynthis Green Modern Science Book Steve White Modern Science Book Steve White Supernova Video SQL/92: SQL> select c.first_name,c.last_name,p.name as product,pt.name as type from customers c inner join purchases pr using(customer_id) 2 inner join products p using (product_id) inner join product_types pt using (product_type_id) order by p.name; FIRST_NAME LAST_NAME PRODUCT TYPE ---------- ---------- ------------------------------ ---------- Cynthis Green Chemistry Book Steve White Chemistry Book Cynthis Green Modern Science Book Steve White Modern Science Book Steve White Supernova Video SQL>
6、使用SQL/92执行多列内连接
SELECT……
FROM TABLE1 INNER JOIN TABLE2
ON TABLE1.COLUMN1 = TABLE2.COLUMN1
AND TABLE1.COLUMN2=TABLE2.COLUMN2;
------------使用using进一步简化
SELECT ……
FROM TABLE1 INNER JOIN TABLE2
USING (COLUMN1,COLUMN2);
7、Oracle特有语法(+)执行外连接，而SQL/92标准使用left/right/full outer join执行外连接
不能使用(+)执行全外连接
SQL> select p.name,pt.name from products p, product_types pt 2 where p.product_type_id=pt.product_type_id(+) order by p.name; NAME NAME ------------------------------ ---------- 2412: The Return Video Chemistry Book Classical Music CD Creative Yell CD From Another Planet DVD Modern Science Book My Front Line Pop 3 CD Space Force 9 DVD Supernova Video Tank War Video Z Files Video 已选择12行。
7.1--使用SQL/92标准left outer join重写上面的查询
SQL> select p.name,pt.name from products p left outer join product_types pt using (product_type_id) order by p.name; NAME NAME ------------------------------ ---------- 2412: The Return Video Chemistry Book Classical Music CD Creative Yell CD From Another Planet DVD Modern Science Book My Front Line Pop 3 CD Space Force 9 DVD Supernova Video Tank War Video Z Files Video 已选择12行。
7.2--全外连接（两个表中有空值的行全列出）
SQL> select p.name,pt.name from products p full outer join product_types pt using(product_type_id) order by p.name;
NAME NAME
------------------------------ ----------
2412: The Return Video
Chemistry Book
Classical Music CD
Creative Yell CD
From Another Planet DVD
Modern Science Book
My Front Line
Pop 3 CD
Space Force 9 DVD
Supernova Video
Tank War Video
Z Files Video
Magazine
test
已选择14行。
8、使用SQL/92执行自连接
SQL> select * from employees;
EMPLOYEE_ID MANAGER_ID FIRST_NAME LAST_NAME TITLE SALARY
----------- ---------- ---------- ---------- -------------------- ----------
1 James Smith CEO 800000
2 1 Ron Johnson Sales Manager 600000
3 2 Fred Hobbs Salesperson 150000
4 2 Susan Jones Salesperson 500000
SQL> select w.last_name || ‘ works for ‘ || m.last_name from employees w, employees m where w.manager_id=m.employee_id;
W.LAST_NAME||‘WORKSFOR‘||M.LAST
-------------------------------
Johnson works for Smith
Jones works for Johnson
Hobbs works for Johnson
SQL> select w.last_name || ‘ works for ‘ || m.last_name from employees w inner join employees m on w.manager_id=m.employee_id;
W.LAST_NAME||‘WORKSFOR‘||M.LAST
-------------------------------
Johnson works for Smith
Jones works for Johnson
Hobbs works for Johnson
9、使用SQL/92执行自连接
select * from product_types,products; --SQL/82标准
select * from product_types cross join products;--SQL/92标准
时间： 2024-10-06 15:58:01