sql - 列を行として選択

Question

select * from emp14;

出力：

EMPLOYEE_ID FIRST_NAME  LAST_NAME   EMAIL   
100          Steven            King         SKING   

次のように出力を列ごとに表示したい：

EMPLOYEE_ID  100
FIRST_NAME   Steven
LAST_NAME    King
EMAIL        SKING

Answer 1

これを試して

SELECT col, val
FROM
(
  SELECT to_char(EMPLOYEE_ID) AS EMPLOYEE_ID,FIRST_NAME,LAST_NAME, EMAIL FROM emp14
)t 
UNPIVOT INCLUDE NULLS
( 
  VAL FOR col IN (EMPLOYEE_ID,FIRST_NAME,LAST_NAME, EMAIL)
);

SQL フィドルのデモ

Answer 2

別のアプローチ:

-- this type is going to contain value's name and the value itself
SQL> create type t_data is object(
  2    col1 varchar2(31),
  3    col2 varchar2(31)
  4  );
  5  /

Type created


SQL> create type t_table is table of t_data;
  2  /

Type created

その後、次の方法でクエリを作成できます。

-- sample of data from the question + some extra  data 
-- just for the sake of demonstration.
SQL> with t1(EMPLOYEE_ID,FIRST_NAME,LAST_NAME,EMAIL) as
  2  (  select 100, 'Steven', 'King', 'SKING' from dual union all
  3     select 101, 'Steven1', 'King1', 'SKING1' from dual
  4   )
  5  select col1
  6       , col2
  7    from t1 t
  8    cross join table(
  9                     t_table( t_data('Employee_id', t.employee_id)
 10                             , t_data('First_name', t.first_name)
 11                             , t_data('Last_Name' , t.last_name)
 12                             , t_data('e-mail'    , t.email)
 13                             )
 14                     )
 15  ;

結果：

COL1                            COL2
------------------------------- -------------------------------
Employee_id                     100
First_name                      Steven
Last_Name                       King
e-mail                          SKING
Employee_id                     101
First_name                      Steven1
Last_Name                       King1
e-mail                          SKING1

8 rows selected

Answer 3

select concat('EMPLOYEE_ID ', EMPLOYEE_ID) as EMPLOYEE_ID,
       concat( 'FIRST_NAME ' ,   FIRST_NAME) as FIRST_NAME,
       concat('LAST_NAME ' ,  LAST_NAME) as LAST_NAME,
       concat('EMAIL ' , EMAIL)  as EMAIL 
from email