Stored Procedures - the total amount of data synchronization

The total amount of 抽取

Will delete all the data target table, then the data source system are all inserted into the target table.
Note: This method ensures the quality of the data, but for the large amount of data tables, the poor performance.

① backup table, backup table structure

--表结构和数据一起备份到目标表
CREATE TABLE EMP_BACK AS (SELECT * FROM EMP ); 

--只备份了表结构
CREATE TABLE EMP_BACK1 AS (SELECT * FROM EMP  WHERE 1 = 2 ); 

② increase the inspection field in the target table to help us determine whether the data actually updated.

ALTER TABLE EMP_BACK1 ADD DATA_DATE  DATE; --新增时间戳字段
ALTER TABLE EMP_BACK1 ADD mark  NUMBER(10); --新增了序列字段

③ increase the master key in the target table, the data to ensure the uniqueness

ALTER TABLE EMP_BACK1 ADD CONSTRAINT PK_EMP_BACK1 PRIMARY KEY(EMPNO);

The data ④TRUNCATE TABLE EMP_BACK1 empty target table

Creating full amount of stored data synchronization process

① create full amount of synchronization stored procedure

CREATE OR REPLACE PROCEDURE SP_EMP_BACK1 --创建存储过程SP_EMP_BACK1
IS 
   V_MARK  NUMBER(10);--声明变量
BEGIN 
  -- 初始化变量
  V_MARK  :=  seq_test2.nextval;--序列下一个值
  
  -- 使用动态SQL 清空目标表，让存储过程支持重跑
  -- 第一种  删除效率比较高，但是必须使用动态SQL执行
  /*EXECUTE IMMEDIATE 'TRUNCATE TABLE EMP_BACK1 ' ;*/   
  
  -- 第二种  直接使用delete 语句删除，记得加条件。
  DELETE FROM EMP_BACK1 WHERE 1 = 1;                   
  
  INSERT INTO EMP_BACK1(empno,
                        ename,
                        job,
                        mgr,
                        hiredate,
                        sal,
                        comm,
                        deptno,
                        DATA_DATE,
                        MARK)
                     SELECT 
                     empno,
                     ename,
                     job,
                     mgr,
                     hiredate,
                     sal,
                     comm,
                     deptno,
                     SYSDATE,
                     V_MARK
                     FROM EMP_BACK  ; 
   COMMIT; --提交                               
END ;

② call a stored procedure oh the whole amount of synchronous data

BEGIN 
  SP_EMP_BACK1;
END ;

③ query whether the data has been synchronized to the target table target table

SELECT * FROM EMP_BACK1;

Exercise
build a target table EMP_SALES (DEPTNO, DNAME, SAL_L1, SAL_L2, SAL_L3, mark) SAL_L1 ~ SAL_L3 corresponding rank 1-3 pay before
check field, require the use of a sequence implemented.
Write a stored procedure, use the full amount of synchronization, updating the target table EMP_SALES

① create the table structure

create table emp_sales(
DEPTNO number(7,2),
DNAME  varchar2(20),
SAL_L1 number(7,2),
SAL_L2 number(7,2),
SAL_L3 number(7,2)，
mark   number(10)
);

② data source table

WITH E AS
(SELECT X.DEPTNO,X.DNAME,X.SAL,X.RN
FROM(
SELECT d.deptno,
       d.dname,
       e.sal,
       dense_rank()OVER(PARTITION BY d.deptno ORDER BY e.sal DESC) RN
FROM emp e,dept d
WHERE e.deptno = d.deptno) X
WHERE X.RN <=3)

SELECT E.DEPTNO,
       E.DNAME,
       MAX(CASE RN WHEN   1 THEN E.SAL END) SAL_L1,
        MAX(CASE RN WHEN 2 THEN E.SAL END) SAL_L2,
          MAX(CASE RN WHEN  3 THEN E.SAL END) SAL_L3
FROM E
GROUP BY E.DEPTNO,E.DNAME;

③ create a sequence

CREATE SEQUENCE MYSEQ
MINVALUE 1
START WITH 1
NOMAXVALUE
INCREMENT BY 1
NOCYCLE
NOCACHE

④ create full amount of synchronization stored procedure

CREATE OR REPLACE PROCEDURE SP_QL_EMP_BACK
IS
V_MARK NUMBER(10);--声明变量
BEGIN
  V_MARK := MYSEQ.NEXTVAL;
    -- 第一种  删除效率比较高，但是必须使用动态SQL执行
    --先清空目标表
  EXECUTE IMMEDIATE 'TRUNCATE TABLE EMP_SALES ' ;  
  INSERT INTO EMP_SALES(DEPTNO,
                        DNAME,
                        SAL_L1,
                        SAL_L2,
                        SAL_L3,
                        MARK)
                        SELECT 
                        DEPTNO,
                        DNAME,
                        SAL_L1,
                        SAL_L2,
                        SAL_L3,
                        V_MARK
                        FROM 
                        (WITH E AS
(SELECT X.DEPTNO,X.DNAME,X.SAL,X.RN
FROM(
SELECT d.deptno,
       d.dname,
       e.sal,
       dense_rank()OVER(PARTITION BY d.deptno ORDER BY e.sal DESC) RN
FROM emp e,dept d
WHERE e.deptno = d.deptno) X
WHERE X.RN <=3)

SELECT E.DEPTNO,
       E.DNAME,
       MAX(CASE RN WHEN   1 THEN E.SAL END) SAL_L1,
        MAX(CASE RN WHEN 2 THEN E.SAL END) SAL_L2,
          MAX(CASE RN WHEN  3 THEN E.SAL END) SAL_L3
FROM E
GROUP BY E.DEPTNO,E.DNAME
) 
COMMIT;
  END ;

⑤ call a stored procedure

 BEGIN
    SP_QL_EMP_BACK;
    END;

⑥ query whether the data has been synchronized to the target table

SELECT * FROM EMP_SALES;