Question

Which of the following are considered as
constraints?
Select one or more:
O a. NULL
O b. Check
O c. Unique
O d. NOT NULL

Answer 1

Answer:

option d is correct answer

Answer 2

Check,Unique, NOT NULL are considered as constraints.

• Unique constraints make guarantee that for every entry in the table, there are unique values for a certain set of columns and no null values. A unique constraint must provide columns that are defined as NOT NULL. When changing the columns of the unique constraint, the database manager utilises a unique index to maintain the key's uniqueness.
• A unique value makes sure that each value in a column is distinct.
• CHECK - Verifies if the values in a column meet a certain requirement.

• A column's values must all be unique according to the UNIQUE constraint. A database table's PRIMARY Key uniquely identifies each row or record. A row or record in any of the provided database tables is uniquely identified by a FOREIGN key.

• The information that can be stored in a column is governed by these criteria. For instance, a column cannot store NULL values if it has a NOT NULL constraint.

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