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Applications often use some form of temporary data store for processes that are to complicated to complete in a single pass.

All INSTEAD OF triggers are fired for each row and you cannot narrow down the event by column.

Instead you can check to see what columns are updated in the body of the trigger by using the UPDATING ('column_name') clause.

INSERT INTO my_temp_table WITH data AS ( SELECT 1 AS id FROM dual CONNECT BY level A new variation of temporary tables has been introduced in Oracle 18c.

A private temporary table is a memory-based temporary table that is dropped at the end of the session or transaction depending on the setup.

tablespace_name, s.extent_management FROM user_tables t, user_tablespaces s WHERE t.tablespace_name = s.

A has two string columns, Text and Match where Match is the "best" prefix for Text, i.e., the foreign key of B which is largest prefix of Text. I'm programming in Delphi and, so far, I'm iterating through A and updating each row with the corresponding match from B. Initially, I wrote a query using the LIKE operator select prefix from B where :text like concat(prefix, '%') order by length(prefix) desc limit 1 I got a 15% gain with select prefix from B where left(:text, length(prefix)) = prefix order by length(prefix) desc limit 1 I don't know how to improve it more.

INSERT INTO my_temp_table WITH data AS ( SELECT 1 AS id FROM dual CONNECT BY level DROP TABLE my_temp_table PURGE; -- Create GTT.

CREATE GLOBAL TEMPORARY TABLE my_temp_table ( id NUMBER, description VARCHAR2(20) ) ON COMMIT PRESERVE ROWS; -- Populate GTT.

create table Employee( 2 ID VARCHAR2(4 BYTE) NOT NULL, 3 First_Name VARCHAR2(10 BYTE), 4 Last_Name VARCHAR2(10 BYTE), 5 Start_Date DATE, 6 End_Date DATE, 7 Salary Number(8,2), 8 City VARCHAR2(10 BYTE), 9 Description VARCHAR2(15 BYTE) 10 ) 11 / Table created.

SQL select * from Employee 2 / ID FIRST_NAME LAST_NAME START_DAT END_DATE SALARY CITY DESCRIPTION ---- -------------------- -------------------- --------- --------- ---------- ---------- --------------- 01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester 8 rows selected.

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DROP TABLE my_temp_table PURGE; -- Create conventional table.