oracle的列轉行

首先建立測試環境

create table test1(

user_account varchar2(100),

signup_date date,

user_email varchar2(100),

friend1_email varchar2(100),

friend2_email varchar2(100),

friend3_email varchar2(100)

);insert into test1

values

('rjbryla',

to_date('2009-08-21', 'yyyy-mm-dd'),

insert into test1

values

('johndoe',

to_date('2009-08-22', 'yyyy-mm-dd'),

null,

null);

--查詢表中的內容

該語句的作用就是將列轉成行，src_col_name.friend_email是臨時變數，unpivot（聚合函式 for 列名 in（型別））是基本語法，其中 in(『』) 中可以指定別名，in中還可以指定子查詢；該語句查詢出來的結果如下圖所示：

oracle11g之前的sql語句為：

select user_account,signup_date,'user_email' as src_col_name,user_email as friend_email from test1

where user_email is not null

union

select user_account,signup_date,'friend1_email' as src_col_name,user_email as friend_email from test1

where friend1_email is not null

union

select user_account,signup_date,'friend2_email' as src_col_name,user_email as friend_email from test1

where friend2_email is not null

union

select user_account,signup_date,'friend3_email' as src_col_name,user_email as friend_email from test1

where friend3_email is not null;