This allows you to clean up data while you’re updating it. This clause lets you delete data from the target table after it is updated, if it meets a condition you specify. If this condition is true, the data is updated, otherwise no data is updated. You can add a WHERE clause into this update clause to update data if another condition is true. For example, if the source row already exists in the target table. The WHEN MATCHED means that this clause only occurs if the ON condition is TRUE for a particular row. This clause specifies the columns and their new values in the target table. This is often done on some kind of ID field, but can be done on other fields that identify the record. If it is false, then the record is inserted, based on what you specify in the insert clause. If it is true, then the record in the target table is updated, based on what you specify in the update clause. This is where you specify the condition that determines if the MERGE statement updates or inserts a row.Įach row in the source table is checked against this condition. It can be a table, a view, or a subquery. This is where you define where the data comes from. You also need to have INSERT and UPDATE privileges on this table to be able to perform a MERGE on it. If you’re using a view, the view needs to be an updatable view. This clause lets you specify the target table name or view name that you are updating or inserting data into. Where the data is being inserted or updated to.The syntax of a MERGE statement in SQL looks like this: MERGE INTO table_name daily, weekly, monthly), and you want to update some record and insert new records. It’s often useful when you need to synchronise data regularly from a source table (e.g. It’s an alternative to a combination of INSERT and UPDATE statements, and it’s faster, and easier to code. The MERGE statement is useful for ETL processes, where you need to move large amounts of data. It’s often called an “upsert”, which is a combination of the word “update” and “insert”, which is what the MERGE statement does. If the record is not found, then an insert can be performed. If the record is found, then an update can be performed. You can analyse records to see if they match between a source and a target table. SQL MERGE is available in Oracle, SQL Server, and Postgres (not MySQL). It’s a bit smarter than an INSERT INTO SELECT statement. The MERGE statement is a type of statement that lets you either insert data or update data, depending on if it already exists. Things to Be Aware Of With the SQL MERGE Statement.Can the Database Update Multiple Tables as Part of the MERGE Statement?.
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