Sql updating primary key value
This “all or nothing” behavior can be modified for arithmetic errors. An exclusive (X) lock is always placed on a table when an update is run.
The lock is held in place until the update statement completes.
In this article we’ll explore how to use the UPDATE statement.
We discuss some best practices, limitations, and wrap-up with several examples.
Suppose you were asked to provide a list of all Adventure Works2012 product categories and subcategories.To do this you could write two separate queries and provide two separate results, such as two spreadsheets, or you could use the UNION clause to deliver one result.When rows are combined duplicate rows are eliminated.Some of the common ones are: In these cases, the UPDATE statement execution stops and the UPDATE generates an error.No rows from the UPDATE statement are saved into the table, even those rows that didn’t generate an error.
If a table has a primary key defined on any field(s), then you cannot have two records having the same value of that field(s).