使用合并在 Oracle 触发器中实现类型 II SCD

Question

我这辈子都无法使以下查询正常工作……本质上它是对以下票证的修改： .

CREATE OR REPLACE TRIGGER TABLE_UPDATE
  AFTER INSERT OR UPDATE ON DIM_TABLE
FOR EACH ROW
DECLARE
PRAGMA AUTONOMOUS_TRANSACTION;
BEGIN
IF INSERTING OR UPDATING
THEN
    MERGE INTO DIM_TABLE T_1
          USING( SELECT COL_1, max(VALID_FROM) AS LAST_DATE FROM 
DIM_TABLE
          GROUP BY COL_1) T_2
          ON (T_1. COL_1= T_2. COL_1)

    WHEN NOT MATCHED THEN INSERT (T_1. VALID_FROM) VALUES(SYSDATE)

    WHEN MATCHED THEN
      UPDATE
      SET T_1.VALID_UNTIL = T_2.LAST_DATE
      WHERE T_1. VALID_UNTIL is null 
      AND T_1. VALID_FROM <> T_2.LAST_DATE;
   COMMIT;
 END IF; 
END;

所需功能：将值输入数据库 (COL_1)。如果该列没有匹配项，则 VALID_FROM 日期将作为 sysdate 输入。如果存在匹配项，则脚本应更新前一行的 VALID_UNTIL 值（直到现在为空，因为它仍然有效）。

我不断收到以下错误：死锁和递归的最大级别超过 (50)

Answer 1

我真的很难满足你的要求。在我看来，您似乎希望 VALID_FROM 成为 sysdate 或每个 COL_1.

的最大值

我会通过使用 :NEW 来操作当前行

set linesize 250
drop table dim_Table;
create table dim_table (col_1 varchar2(50), valid_from timestamp);

CREATE OR REPLACE TRIGGER TABLE_UPDATE
  before INSERT OR UPDATE ON DIM_TABLE
FOR EACH ROW
DECLARE
  l_valid_from date;
BEGIN
  select max(valid_from) 
    into l_valid_from
   from  dim_table t1
   where t1.col_1 = :new.col_1;
   if l_valid_from is null then
     :new.valid_from := sysdate;
   else
     :new.valid_from := l_valid_from;
   end if;
END;

insert into dim_table (col_1) values ('TEST1');
select * from dim_table;
exec dbms_lock.sleep(1);
insert into dim_table (col_1) values ('TEST1');
select * from dim_table;
exec dbms_lock.sleep(1);
insert into dim_table (col_1) values ('TEST2');
select * from dim_table;
exec dbms_lock.sleep(1);
insert into dim_table (col_1) values ('TEST1');
select * from dim_table;
exec dbms_lock.sleep(1);
insert into dim_table (col_1) values ('TEST2');
select * from dim_table;

输出：

Table dropped.
Table created.
Trigger created.
1 row created.

COL_1                                              VALID_FROM                                        
-------------------------------------------------- --------------------------------------------------
TEST1                                              30/04/2019 09:13:10.000000                        
1 row selected.
 PL/SQL procedure successfully completed.
1 row created.

COL_1                                              VALID_FROM                                        
-------------------------------------------------- --------------------------------------------------
TEST1                                              30/04/2019 09:13:10.000000                        
TEST1                                              30/04/2019 09:13:10.000000                        

2 rows selected.
 PL/SQL procedure successfully completed.
1 row created.

COL_1                                              VALID_FROM                                        
-------------------------------------------------- --------------------------------------------------
TEST1                                              30/04/2019 09:13:10.000000                        
TEST1                                              30/04/2019 09:13:10.000000                        
TEST2                                              30/04/2019 09:13:12.000000                        

3 rows selected.
 PL/SQL procedure successfully completed.
1 row created.

COL_1                                              VALID_FROM                                        
-------------------------------------------------- --------------------------------------------------
TEST1                                              30/04/2019 09:13:10.000000                        
TEST1                                              30/04/2019 09:13:10.000000                        
TEST2                                              30/04/2019 09:13:12.000000                        
TEST1                                              30/04/2019 09:13:10.000000                        

4 rows selected.
 PL/SQL procedure successfully completed.
1 row created.

COL_1                                              VALID_FROM                                        
-------------------------------------------------- --------------------------------------------------
TEST1                                              30/04/2019 09:13:10.000000                        
TEST1                                              30/04/2019 09:13:10.000000                        
TEST2                                              30/04/2019 09:13:12.000000                        
TEST1                                              30/04/2019 09:13:10.000000                        
TEST2                                              30/04/2019 09:13:12.000000                        

5 rows selected.

Answer 2

谢谢@hol，@Alex Poole，我想我破解了它。每次添加任何内容时，我都使用触发器将数据插入 VALID_FROM：

 CREATE TABLE "DIM_TEST" (  "COL_1" VARCHAR2(20 BYTE), "VALID_UNTIL" TIMESTAMP (6), 
"DIM_TEST_PK" NUMBER, "VALID_FROM" TIMESTAMP (6) DEFAULT NULL) 

  create or replace TRIGGER T_DIM_TEST_DATE_INSERT
  BEFORE INSERT ON DIM_TEST
  FOR EACH ROW
  BEGIN
    :new.VALID_FROM := sysdate;
  END;

对于在添加重复项时更新前一行 VALID_FROM 的部分，我有以下触发器：

 create or replace TRIGGER TABLE_UPDATE
 after INSERT or update
 ON DIM_TEST
 FOR EACH ROW
 DECLARE
 PRAGMA AUTONOMOUS_TRANSACTION;
 BEGIN
 IF INSERTING
 THEN
    MERGE INTO DIM_TEST T_1
    USING (select :new.COL_1 from DUAL) T_2
      ON (T_1.COL_1 = :new.COL_1)

WHEN MATCHED THEN
  UPDATE
  SET T_1.VALID_UNTIL = (SYSDATE)
  WHERE T_1. VALID_UNTIL is null;
  --AND T_1. VALID_FROM <> (SELECT max(VALID_FROM) FROM DIM_TEST);
 END IF;  
COMMIT;
END;

唯一的缺点是，如果将现有行更新为重复行，则第二个触发器将不会触发，因为 IF INSERTING 子句...当我将其更改为 IF INSERTING or UPDATING 那么它会产生一个无限循环...但我可以限制用户只能插入所以这应该不是问题。

使用合并在 Oracle 触发器中实现类型 II SCD

Implement type II SCD in Oracle trigger with using merge

oracle

triggers

plsql

database-trigger

scd