oracleのcreate table with asとinsert into with as文

oracleはwith as句を使用してテーブル構文を作成することをサポートします:create table table_name as with clause_name as (select query )[, clause_name1 as (select query ) ...]select column1,...columnn from clause_name;
構文:insert into table_name with clause_name as (select query )[, clause_name1 as (select query ) ...]select column1,...columnn from clause_name;
例:--create with文

CREATE TABLE w_test_20 AS 

WITH  data_info_19 AS 
  (SELECT 
         NVL(ename,'unknow employee') AS ename, 
         DECODE(deptno,10,'ACCOUNTING',20,'RESEARCH',30,'SALES',40,'OPERATIONS','no this department') AS dname,
         NVL(job,'unkown job') AS job ,
         substr(to_char(hiredate,'yyyy-mm-dd'),1,7) AS hiredate,
         CASE WHEN sal <= 1000 THEN 'D' 
              WHEN sal > 1000 AND sal <= 2000 THEN 'C'
              WHEN sal > 2000 AND sal <= 3000 THEN 'B'
              WHEN sal > 3000  THEN 'A'
              ELSE 'unkown grade' 
         END AS grade,
         ROUND(sal,2) AS sal,
         FLOOR(nvl(comm,0)) AS comm,
         NVL(sal,0)+NVL(comm,0) AS total_sal
     FROM emp WHERE deptno IN 
     (SELECT DISTINCT deptno FROM dept))

 SELECT * FROM data_info_19;

CREATE TABLE w_test_18 AS 
WITH dept_info AS 
(SELECT deptno AS deptno_1,dname FROM dept)
,
emp_info AS
(SELECT empno AS empno_1,ename,job,deptno FROM emp)
,
other_info AS
(SELECT empno,hiredate,NVL(sal,0)+NVL(comm,0) AS total_sal FROM emp )

SELECT * FROM dept_info d LEFT JOIN emp_info e ON d.deptno_1=e.deptno RIGHT JOIN other_info o ON e.empno_1=o.empno ;

INSERT INTO w_test_19
WITH  data_info_19 AS 
  (SELECT 
         NVL(ename,'unknow employee') AS ename, 
         DECODE(deptno,10,'ACCOUNTING',20,'RESEARCH',30,'SALES',40,'OPERATIONS','no this department') AS dname,
         NVL(job,'unkown job') AS job ,
         substr(to_char(hiredate,'yyyy-mm-dd'),1,7) AS hiredate,
         CASE WHEN sal <= 1000 THEN 'D' 
              WHEN sal > 1000 AND sal <= 2000 THEN 'C'
              WHEN sal > 2000 AND sal <= 3000 THEN 'B'
              WHEN sal > 3000  THEN 'A'
              ELSE 'unkown grade' 
         END AS grade,
         ROUND(sal,2) AS sal,
         FLOOR(nvl(comm,0)) AS comm,
         NVL(sal,0)+NVL(comm,0) AS total_sal
     FROM emp WHERE deptno IN 
     (SELECT DISTINCT deptno FROM dept))

 SELECT * FROM data_info_19;

INSERT INTO  w_test_18 
WITH dept_info AS 
(SELECT deptno AS deptno_1,dname FROM dept)
,
emp_info AS
(SELECT empno AS empno_1,ename,job,deptno FROM emp)
,
other_info AS
(SELECT empno,hiredate,NVL(sal,0)+NVL(comm,0) AS total_sal FROM emp )

SELECT * FROM dept_info d LEFT JOIN emp_info e ON d.deptno_1=e.deptno RIGHT JOIN other_info o ON e.empno_1=o.empno ;