Oracle merge where clause example

You can add an optional DELETE WHERE clause to the MATCHED clause to clean up after a merge operation. The DELETE clause deletes only the rows in the target table that match both ON and DELETE WHERE clauses. Oracle MERGE prerequisites. To execute the MERGE statement, you must have the INSERT and UPDATE object privileges on the source tables.

If you use the DELETE clause, you must also have the DELETE object privilege on the target table. I have noticed WHERE clause can be used in different ways in a MERGE statement.

Though both statements give the same result in this example , is there a recommended way to use WHERE clause in MERGE statement ? It’s a bit smarter than an INSERT INTO SELECT statement. You can analyse records to see if they match between a source and a target table. Use a single merge statement to update the upd_services table with the data in the table upd_services_changes_2.

This merge will include updates , deletes and inserts. For this task, a delete is indicated by a negative price in the changes table. Consider the following example where data from the HR_RECORDS table is merged into the EMPLOYEES table. MERGE INTO employees e USING hr_records h ON (e.id = h.emp_id) WHEN MATCHED THEN UPDATE SET e. Secon the WHERE clause filtered rows based on the condition e.

Thir the SELECT clause chose the columns that should be returned. Note: Primarily of value when moving large amounts of data in data warehouse situations. Description This example creates item price table catalogto capture the price of various items. A second table is created with updated item and price information.

In order to roll all the info into the original catalogtable, merge is use since this is a standard UPDATE-else-INSERT task. To insert all of the source rows into the table, you can use a constant filter predicate in the ON clause condition. An example of a constant filter predicate is ON ( 0=).

First, the FROM clause specified the table for querying data. MERGE INTO payments p USING new_payments np ON (p.id = np.id) WHEN NOT MATCHED THEN WHEN MATCHED THEN UPDATE SET p. Examples of Merge Statement’s Output Clause We are using the same tables and merge statement as used in an example previously. Below are just four simple ways you can use output clause with the merge statement.

Let us discuss a few examples on the MERGE statement using demo tables. Below is the syntax of the MERGE statement in SQL Server. Example of Merge Statement Let us take a simple example of merge statement : There are two tables Mobiles and Mobiles_New. We have to update the Mobiles table based on the Mobiles_New table so that: 1. Mobiles that exist in both the Mobiles_New table and the Mobiles table are updated in the Mobiles table with new names.

Statement Merge all the new info into the original catalogtable MERGE INTO catalogsUSING catalogsON (s1.id = s2.id) WHEN MATCHED THEN UPDATE SET s1. There is no WHERE in that part of the MERGE statement. See MERGE (Transact-SQL) in the documentation for syntax help.

The UPDATE or INSERT clauses became optional, so you could do either or both. Also, a DELETE capability was added to the.