Sql updating primary key value
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).Note − You would use these concepts while creating database tables.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.
This is usually the result of denormalizing (reversing normalization) and involves using the foreign key in one table to look up column values by using the primary key in another.A primary key is a field in a table which uniquely identifies each row/record in a database table. When multiple fields are used as a primary key, they are called a composite key.