Oracle Merge Statements

General Information
Library Note Morgan's Library Page Header
Coming to OpenWorld 2018? Be sure to visit the TidalScale booth in Moscone South and learn how to solve performance problems and lower costs with Software Defined Servers. Before you visit the booth, or if you can't make it this year, check out TidalScale at Be sure to click on the Solutions link and look through the Oracle resources.
Usage Note Primarily of value when moving large amounts of data in data warehouse situations according to some people but in my opinion these statements don't belong anywhere unless the data volumes are so small as to be almost laughable. The reason I will not use these statements is very simply that they are brain dead. By which I mean that they assume there is an equal probability of the record being inserted or updated or deleted: This is never the case.

If the probability is that the record exists to be updated then use a FORALL UPDATE with SAVE EXCEPTIONS or an error logging table (DBMS_ERRLOG) and clean up the small number of failures that occur.
Demo tables and data conn uwclass/uwclass@pdbdev

CREATE TABLE employee (
employee_id NUMBER(5),
first_name  VARCHAR2(20),
last_name   VARCHAR2(20),
dept_no     NUMBER(2),
salary      NUMBER(10));

INSERT INTO employee VALUES (1, 'Dan', 'Morgan', 10, 100000);
INSERT INTO employee VALUES (2, 'Helen', 'Lofstrom', 20, 100000);
INSERT INTO employee VALUES (3, 'Akiko', 'Toyota', 20, 50000);
INSERT INTO employee VALUES (4, 'Jackie', 'Stough', 20, 40000);
INSERT INTO employee VALUES (5, 'Richard', 'Foote', 20, 70000);
INSERT INTO employee VALUES (6, 'Joe', 'Johnson', 20, 30000);
INSERT INTO employee VALUES (7, 'Clark', 'Urling', 20, 90000);

CREATE TABLE bonuses (
employee_id NUMBER, bonus NUMBER DEFAULT 100);

INSERT INTO bonuses (employee_id) VALUES (1);
INSERT INTO bonuses (employee_id) VALUES (2);
INSERT INTO bonuses (employee_id) VALUES (4);
INSERT INTO bonuses (employee_id) VALUES (6);
INSERT INTO bonuses (employee_id) VALUES (7);

SELECT * FROM employee;

SELECT * FROM bonuses;
Merge Statement
Conditional INSERT,  UPDATE, or DELETE MERGE <hint> INTO <table_name>
USING <table_view_or_query>
ON (<condition>)
WHEN MATCHED THEN <update_clause>
DELETE <where_clause>
WHEN NOT MATCHED THEN <insert_clause>
[LOG ERRORS <log_errors_clause> <reject limit <integer | unlimited>];
MERGE INTO bonuses b
  SELECT employee_id, salary, dept_no
  FROM employee
  WHERE dept_no =20) e
ON (b.employee_id = e.employee_id)
  UPDATE SET b.bonus = e.salary * 0.1
  DELETE WHERE (e.salary < 40000)
  INSERT (b.employee_id, b.bonus)
  VALUES (e.employee_id, e.salary * 0.05)
  WHERE (e.salary > 40000);

SELECT * FROM bonuses;

Related Topics
Array Processing
Error Logging
Insert Statements
Oracle Built-in Functions
Update Statements
What's New In 12cR1
What's New In 12cR2

Morgan's Library Page Footer
This site is maintained by Dan Morgan. Last Updated: This site is protected by copyright and trademark laws under U.S. and International law. © 1998-2017 Daniel A. Morgan All Rights Reserved