COMPUTER SCIENCE AND ENGINEERING
SQL
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
TRUE
|
|
|
FALSE
|
|
|
Either A or B
|
|
|
None of the above
|
Detailed explanation-1: -The NOT NULL constraint enforces a column to NOT accept NULL values. This enforces a field to always contain a value, which means that you cannot insert a new record, or update a record without adding a value to this field.
Detailed explanation-2: -The NOT NULL constraint is used to ensure that a given column of a table is never assigned the null value. Once a NOT NULL constraint has been defined for a particular column, any insert or update operation that attempts to place a null value in that column will fail.
Detailed explanation-3: -A NOT NULL constraint is a rule that prevents null values from being entered into one or more columns within a table. A unique constraint (also referred to as a unique key constraint) is a rule that forbids duplicate values in one or more columns within a table.
Detailed explanation-4: -The NOT NULL constraint enforces a column to not accept NULL values, which means that you cannot insert or update a record without adding a value to this field.
Detailed explanation-5: -To enforce NOT NULL for a column in SQL Server, use the ALTER TABLE .. ALTER COLUMN command and restate the column definition, adding the NOT NULL attribute.