You cannot use an update query to add new records to a database, or to delete entire records from a database.
To add new records to a database you use an append query, and to delete whole records from a database you use a delete query.
As a best practice, there are two main steps that you must follow to create and run an update query: create a select query that identifies the records that you want to update, and then convert that query to an update query that you can run to update the records.
Tip: You might want to back up your database before you run an update query.
Also, if the table you're updating is the same as the table in the FROM clause and the FROM clause contains only one reference to the table, an alias might not be specified.Our goal here is to add a new temporary column to contain the sales information.We do not want to overwrite any of the existing columns in the UK Regions table.The sample code in Listing 1 demonstrates that you can use the FROM clause combined with a JOIN operation to update specified columns from a second table.When you design relational expressions, you have to decide whether you want a single row to match multiple rows (in a one-to-many—1: M—relationship) or you want many rows to match a single row in the joined table (i.e., you want to update all rows).