[Oracle] Insert All神奇

转载

mb5fed6ec4336ce 2015-07-30 12:55:00

文章标签 多表数据 ico 行转列 sql 文章分类 Java 后端开发

无条件插入

Oracle中间insert all它指的是相同的数据组成不同的表。如果有需求现在：该t插入数据表t1,t2，假设你不知道insert all。您可以使用insert插入2次要，例如，见下文：

insert  into t1(object_name,object_id) select * from t;
insert  into t2(object_name,object_id) select * from t;
commit;

其实。以上这样的写法是错误的，由于在两次insert的过程中，t表的数据有可能已经发生了变化，也就是说。t1,t2表得到的数据有可能不一样。正确的写法应该是採用insert all：

insert all
into t1(object_name,object_id)
into t2(object_name,object_id)
select * from t;
commit;

有条件的插入

insert first/all 是对每一行来进行推断

两者差别：

insert first：对于每一行数据，仅仅插入到第一个when条件成立的表，不继续检查其它条件。

insert all ：对于每一行数据，对每个when条件都进行检查。假设满足条件就运行插入操作。

看以下的样例：

--insert first
--前面等于1的条件被<=5含在内，FIRST就表示前面插入了。后面不会再插入了。
insert first
when object_id = 1 then
into t1(object_name,object_id)
when object_id <=5 then                      
into t2(object_name,object_id)
select * from t;
commit;

select * from t1;

OBJECT_NAME                OBJECT_ID
--------------------------------- ---
ICOL$                              1

select * from t2;

OBJECT_NAME                OBJECT_ID
--------------------------------- ---
I_USER1                            2
CON$                               3
UNDO$                              4
C_COBJ#                            5

--insert all
insert all
when object_id = 1 then
into t1(object_name,object_id)
when object_id <=5 then                      
into t2(object_name,object_id)
select * from t;
commit;

SQL> select * from t1;

OBJECT_NAME                OBJECT_ID
--------------------------------- ---
ICOL$                              1
SQL> select * from t2;

OBJECT_NAME                OBJECT_ID
--------------------------------- ---
ICOL$                              1
I_USER1                            2
CON$                               3
UNDO$                              4
C_COBJ#                            5

行转列插入

insert all还能够实现行转列插入：

select * from sales_source_data;
EMPLOYEE_ID    WEEK_ID  SALES_MON  SALES_TUE  SALES_WED SALES_THUR  SALES_FRI
----------- ---------- ---------- ---------- ---------- ---------- ----------
        176          6       2000       3000       4000       5000       6000

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;

select * from sales_info;
EMPLOYEE_ID       WEEK      SALES
----------- ---------- ----------
        176          6       2000
        176          6       3000
        176          6       4000
        176          6       5000
        176          6       6000