oracle 常用語句彙總

一.複製表資料至另一張表

直接建相同的表並將資料複製過去：
create table students_backup as select * from students;
只建相同的表結構：
create table students_backup as select * from students where 1=2;
表已建好，直接複製資料：
insert into students_backup select * from students
二.兩表(多表)關聯update

--

這次提取的資料都是vip，且包括新增的,所以順便更新客戶類別
update customers a --
使用別名
set customer_type='01
'--01 為vip，00為普通
where
exists (select
1from
tmp_cust_city b
where b.customer_id=
a.customer_id
)

2. 被修改值由另乙個表運算而來

update customers a --

使用別名
set city_name=(select b.city_name from tmp_cust_city b where b.customer_id=
a.customer_id)
where
exists (select
1from
tmp_cust_city b
where b.customer_id=
a.customer_id)--
update 超過2個值
update customers a --
使用別名
set (city_name,customer_type)=(select
b.city_name,b.customer_type
from
tmp_cust_city b
where b.customer_id=
a.customer_id)
where
exists (select
1from
tmp_cust_city b
where b.customer_id=
a.customer_id
)

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