Oracle笔记-Multitable INSERT 的用法

[转自]  http://blog.chinaunix.net/uid-8504518-id-3310531.html

为避免日趋衰退的记忆力，参考官方E文文档《Introduction to Oracle9i：SQL Ed 2.0.pdf》第20章，写成自己的文字，以供日后查阅。

一、Insert基础用法

语法：

    Insert Into 表名 (字段1,字段2,字段3...）

    Values (值1,值2,值3...）

例子：

INSERT INTO departments(department_id, department_name,
manager_id, location_id)
VALUES      (70, 'Public Relations', 100, 1700);

语法：

    Insert Into 表名 (字段1,字段2,字段3...）

    select 语句

不做任何解释，实在是没啥好说的〇_〇，注意别跟create table ...as select一样，insert中的select前面可没as ^_^

二、Unconditional INSERT ALL 用法

直接拿例子了：

INSERT  ALL
   INTO sal_history VALUES(EMPID,HIREDATE,SAL)
   INTO mgr_history VALUES(EMPID,MGR,SAL)
   SELECT employee_id EMPID, hire_date HIREDATE,
                  salary SAL, manager_id MGR
   FROM  employees
   WHERE employee_id > 200;

解释：将select查询出来的结果，每返回一行就分别插入表sal_history 和mgr_history 中，优点就是只做一次查询即可分别查询2个表，假如使用基础用法，将进行2次查询。

三、Conditional INSERT ALL

还是直接拿例子：

INSERT ALL
    WHEN SAL > 10000 THEN
        INTO sal_history VALUES(EMPID,HIREDATE,SAL)
   WHEN MGR > 200   THEN
       INTO mgr_history VALUES(EMPID,MGR,SAL)
   SELECT employee_id EMPID,hire_date HIREDATE,  
                  salary SAL, manager_id MGR
   FROM   employees
   WHERE  employee_id > 200;

解释：将select查询出来的结果，每返回一行就判断，SAL > 10000 就插入表sal_history ，MGR > 200就插入mgr_history ，优点和前面提到一样。

四、Conditional FIRST INSERT

仍然是例子：

INSERT FIRST
   WHEN SAL  > 25000          THEN
       INTO special_sal VALUES(DEPTID, SAL)
   WHEN HIREDATE like ('%00%') THEN
      INTO hiredate_history_00 VALUES(DEPTID,HIREDATE)
   WHEN HIREDATE like ('%99%') THEN
      INTO hiredate_history_99 VALUES(DEPTID, HIREDATE)
   ELSE
      INTO hiredate_history VALUES(DEPTID, HIREDATE)
   SELECT department_id DEPTID, SUM(salary) SAL,
                  MAX(hire_date) HIREDATE
   FROM   employees
   GROUP BY department_id;

解释：将select查询出来的结果，每返回一行就判断，SAL  > 25000就插入表special_sal ，否则HIREDATE like ('%00%') ，符合就插入hiredate_history_00，前面2个条件还是不成力，就判断HIREDATE like ('%99%') ，符合就插入表hiredate_history_99 ，前面3个条件都不符合，只好插入表hiredate_history 了。

打完这我都头晕了，假如学过程序设计，看下面的清晰明了：

if  SAL  > 25000 then

    INTO special_sal VALUES(DEPTID, SAL)
else

(

    if HIREDATE like ('%00%') THEN

         INTO hiredate_history_00 VALUES(DEPTID,HIREDATE)
    else

        (

            if HIREDATE like ('%99%') THEN

                INTO hiredate_history_99 VALUES(DEPTID, HIREDATE)
            else

                INTO hiredate_history VALUES(DEPTID, HIREDATE)
        )

 )

假如还看不理解，看官方的这句话吧，“If the first WHEN clause evaluates to true, the subsequent WHEN clauses for this row should be skipped.”

五、Pivoting INSERT

最后还是例子：

INSERT ALL
   INTO sales_info VALUES (employee_id,week_id,sales_MON)
   INTO sales_info VALUES (employee_id,week_id,sales_TUE)
   INTO sales_info VALUES (employee_id,week_id,sales_WED)
   INTO sales_info VALUES (employee_id,week_id,sales_THUR)
   INTO sales_info VALUES (employee_id,week_id, sales_FRI)
SELECT EMPLOYEE_ID, week_id, sales_MON, sales_TUE,
              sales_WED, sales_THUR,sales_FRI
FROM sales_source_data;

解释：老实说，看不出有啥用法，真的非要说，咱就把它当作行列转换吧，如果上面表在加多一列，比如INTO sales_info VALUES (employee_id,week_id,week_which,sales_MON) 改成 INTO sales_info VALUES (employee_id,week_id,'星期一',sales_MON)