Row compare and insert into log table only changed data - sql

Question

I'm trying to compare a global temporary table to another table and want to insert into a log table but can not seem to find the best/most efficient way to accomplish this.
Log Table
CREATE TABLE LogTable
(
Date_Time DATETIME,
Name VARCHAR2(10 CHAR),
old VARCHAR2(20 CHAR),
new VARCHAR2(20 CHAR),
)
Object Type
CREATE OR REPLACE type dbo.P_REC AS OBJECT
(
ATTR1 VARCHAR2(10 CHAR),
ATTR2 VARCHAR2(20 CHAR),
ATTR3 VARCHAR2(20 CHAR),
ATTR4 VARCHAR2(20 CHAR)
);
Collection Type
CREATE OR REPLACE type dbo.P_REC_LIST IS TABLE OF P_REC;
Stored Procedure
PROCEDURE PASSPEOPLETOORACLE(tmpCollection IN P_REC_LIST , resultCursor out sys_refcursor)
IS
BEGIN
IF tmpCollection .count > 0 THEN
INSERT INTO tmpPTbl SELECT * FROM table1; <--tmpPTbl is a copy of table1 before the merge statement.
MERGE INTO table1 MKTP
USING (
WITH tmpTBL AS
(
SELECT ADCOLL.ATTR1,
ADCOLL.ATTR2,
MV.ATTR3,
MV.ATTR4
FROM TABLE(tmpCollection) ADCOLL
LEFT JOIN materializedView MV
ON ADCOLL.ATTR1 = MV.ATTR1
)
SELECT DISTINCT COALESCE(tmpTBL.ATTR1,MKtmpTBL.ATTR1) AS ATTR1,
tmpTBL.ATTR2,
tmpTBL.ATTR3,
tmpTBL.ATTR4,
CASE WHEN tmpTBL.ATTR1 IS NULL
THEN 'Y' ELSE 'N' END
match_flag FROM tmpTBL
FULL JOIN table1 MKtmpTBL
ON MKtmpTBL.ATTR1 = tmpTBL.ATTR1
) usingTBL
ON (MKTP.ATTR1 = usingTBL.ATTR1)
WHEN MATCHED THEN
UPDATE SET MKTP.ATTR2 = usingTBL.ATTR2,
MKTP.ATTR3 = usingTBL.ATTR3,
MKTP.ATTR4 = usingTBL.ATTR4,
DELETE WHERE match_flag = 'Y'
WHEN NOT MATCHED THEN
INSERT (ATTR1)
VALUES (usingTBL.ATTR1);
END IF;
END;
Id like a way to compare the newly update records in table1 to the prior records in tmpPTbl and where the old and new values differ, insert a new row into the log table.
2019-02-14 23:59:59,jdoe,abcd,efgh would be an example of a record inserted into the log table.
tmpPTbl & table1 both have 50 columns in them & about 16k rows on average.

Answer 1

The best solution for you would be to create a Trigger on table Table1. So that any operation occurs on Table1 it can be logged to Logtable. See below demo:
CREATE TABLE table1
(col1 VARCHAR2(10),
col2 VARCHAR2(10),
col3 VARCHAR2(10) );
/
--Trigger
CREATE OR REPLACE TRIGGER Log_Entry before
INSERT OR
UPDATE ON table1 FOR EACH row
BEGIN
IF INSERTING THEN
INSERT INTO LogTable VALUES
(sysdate, :new.col1, :new.col2, :new.col3
);
ELSIF UPDATING THEN
INSERT INTO LogTable VALUES
(sysdate, :old.col1, :old.col2, :old.col3
);
END IF;
END;
/
Execution:
SQL> Insert into table1 values ('A','B','C');
SQL>Update table1
set col1 ='Z'
where col1 = 'A';
SQL> Merge INTO table1 tb1 USING
(SELECT 'Z' col1 , 'D' col2, 'K' col3 FROM dual
) tb2 ON (tb1.col1 = tb2.col1)
WHEN matched THEN
UPDATE SET tb1.col2=tb2.col2 WHEN NOT matched THEN
INSERT VALUES
(tb2.col1,tb2.col2,tb2.col3
);
SQL>Commit;
SQL> Select * from logtable;
DATE_TIME NAME OLD NEW
--------- ---------- -------------------- --------------------
15-FEB-19 A B C
15-FEB-19 Z B C
15-FEB-19 Z B C
Note there is no need to copy data to tmpPTbl table as well.