关于Oracle SQL/82标准和SQL/92标准

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
---------- --------------- ------------------------------ -------------------------------------------------- ----------
                         Modern Science                 A description of modern science                     19.95
                         Chemistry                      Introduction to Chemistry
                         Supernova                      A star explodes                                     25.99
                         Tank War                       Action movie about a future war                     13.95
                         Z Files                        Series on mysterious activities                     49.99
                         : The Return               Aliens return                                       14.95
                         Space Force                   Adventures of heroes                                13.49
                         From Another Planet            Alien from another planet lands on Earth            12.99
                         Classical Music                The best classical music                            10.99
                        Pop                           The best popular music                              15.99
                        Creative Yell                  Debut album                                         14.99
                         My Front Line                  Their greatest hits                                 13.49

已选择12行。

SQL> select * from product_types;

PRODUCT_TYPE_ID NAME
--------------- ----------
               Book
               Magazine
               CD
               DVD
               Video
             test

已选择6行。

SQL> SELECT * FROM PURCHASES;

PRODUCT_ID CUSTOMER_ID   QUANTITY
---------- ----------- ----------

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
------------------------------ ----------
: The Return               Video
Chemistry                      Book
Classical Music                CD
Creative Yell                  CD
From Another Planet            DVD
Modern Science                 Book
Pop                           CD
Space Force                   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
------------------------------ ----------
: The Return               Video
Chemistry                      Book
Classical Music                CD
Creative Yell                  CD
From Another Planet            DVD
Modern Science                 Book
Pop                           CD
Space Force                   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
: The Return               Video
Space Force                   DVD
From Another Planet            DVD
Classical Music                CD
Pop                           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  行出现错误:
ORA-: 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
Chemistry                      Book
Z Files                        Video
Tank War                       Video
Supernova                      Video
: The Return               Video
Space Force                   DVD
From Another Planet            DVD
Classical Music                CD
Pop                           CD
Creative Yell                  CD                       

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  行出现错误:
ORA-: 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/:
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
    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/:
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)
    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
    where p.product_type_id=pt.product_type_id(+) order by p.name;

NAME                           NAME
------------------------------ ----------
: The Return               Video
Chemistry                      Book
Classical Music                CD
Creative Yell                  CD
From Another Planet            DVD
Modern Science                 Book
My Front Line
Pop                           CD
Space Force                   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
------------------------------ ----------
: The Return               Video
Chemistry                      Book
Classical Music                CD
Creative Yell                  CD
From Another Planet            DVD
Modern Science                 Book
My Front Line
Pop                           CD
Space Force                   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
------------------------------ ----------
: The Return               Video
Chemistry                      Book
Classical Music                CD
Creative Yell                  CD
From Another Planet            DVD
Modern Science                 Book
My Front Line
Pop                           CD
Space Force                   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
----------- ---------- ---------- ---------- -------------------- ----------
                      James      Smith      CEO
                     Ron        Johnson    Sales Manager
                     Fred       Hobbs      Salesperson
                     Susan      Jones      Salesperson              

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