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Do primary keys provide meaningful business information?
A logical primary key meaningful to the business is critical for properly normalizing the data. A physical primary key and its corresponding foreign key are critical for properly navigating a database to store and retrieve data.
Can address be used as a primary key?
Yes, it is a bad primary key because your users will want to update their email addresses. yes, it is better if you use an integer instead. you can also set your email column as unique constraint. Another reason why integer primary key is better is when you refer to email address in different table.
Can an email be used as a primary key?
Which one of the following can be taken as a primary key?
Answer: C. The attributes name, street, and department can repeat for some tuples. But the id attribute has to be unique.So it forms a primary key.
Which one of the following should be taken as a primary key?
Which one of the following attribute can be taken as a primary key? Explanation: The attributes name, street and department can repeat for some tuples. But the id attribute has to be unique. So it forms a primary key.
Is there a limit to the number of foreign key references?
Greater than 253 foreign key references are not currently available for columnstore indexes, memory-optimized tables, Stretch Database, or partitioned foreign key tables. Unlike primary key constraints, creating a foreign key constraint does not automatically create a corresponding index.
Can a table have more than one primary key?
Remember there is nothing special about a primary key, except that it is labelled as such. It is nothing more than a NOT NULL UNIQUE constraint, and a table can have more than one. If you use a surrogate key, you still want a business key to ensure uniqueness according to the business rules.
When do primary key constraints guarantee unique data?
Because primary key constraints guarantee unique data, they are frequently defined on an identity column. When you specify a primary key constraint for a table, the Database Engine enforces data uniqueness by automatically creating a unique index for the primary key columns.
When do you add foreign key rules to referential integrity?
Additional foreign key rules may be added when setting referential integrity, such as what to do with the child rows (in the Orders table) when the record with the PK, part of the parent (Customer), is deleted or changed (updated).