What Is The NULL Keyword Used For?

The null keyword is a literal that represents a null reference, one that does not refer to any object. null is the default value of reference-type variables. Ordinary value types cannot be null, except for nullable value types.



Is NULL 0 justify?

Explanation: NULL basically means no value, or unknown, it is not to be confused with 0 which is a numeric value by itself. NULL value could be either empty, meaningless, or not even initialized.


Is NULL or empty in SQL?

NULL is used in SQL to indicate that a value doesn't exist in the database. It's not to be confused with an empty string or a zero value. While NULL indicates the absence of a value, the empty string and zero both represent actual values.


What is NULL attribute?

In general, a null attribute value is the equivalent of nothing. However, it's important to be precise in our terminology because there are many ways to represent nothing: An attribute has a value that indicates nothingness (null) An attribute exists but has no value (empty) An attribute doesn't exist (missing)


What is NULL attribute example?

The value of any operation on a NULL value is also defined as NULL. For example, if a record has a value of 4 for Quantity and a NULL value for Price, then the value of Quantity + Price is considered to be NULL.


How do we represent NULL values?

A NULL value is used to represent a missing value, but that it usually has one of three different interpretations:

  1. The value unknown (value exists but is not known)
  2. Value not available (exists but is purposely withheld)
  3. Attribute not applicable (undefined for this tuple)


What does NULL value mean?

A null value in a relational database is used when the value in a column is unknown or missing. A null is neither an empty string (for character or datetime data types) nor a zero value (for numeric data types).


What is the NULL keyword used for?

The null keyword is a literal that represents a null reference, one that does not refer to any object. null is the default value of reference-type variables. Ordinary value types cannot be null, except for nullable value types.


Does NULL and zero give reason?

No its not the same as null means a value that is unavailable unassigned or unknown and zero is a defined value.


WHAT IS NULL value logic?

The SQL null value basically means “could be anything”. It is therefore impossible to tell whether a comparison to null is true or false. That's where the third logical value, unknown, comes in. Unknown means “true or false, depending on the null values”.


WHAT IS NULL value in Java?

In Java, a null value can be assigned to an object reference of any type to indicate that it points to nothing. Calling a method on a null reference will throw a NullPointerException : Blog blog = null; long id = blog. getId(); // NullPointerException.


What is the use of NULL value give example?

What is a NULL Value? A field with a NULL value is a field with no value. If a field in a table is optional, it is possible to insert a new record or update a record without adding a value to this field. Then, the field will be saved with a NULL value.


IS NULL means blank?

Answer: Null indicates there is no value within a database field for a given record. It does not mean zero because zero is a value. Blank indicates there is a value within a database but the field is blank.


What is NULL and NOT NULL in database?

When creating a table or adding a column to a table, you need to specify the column value optionality using either NULL or NOT NULL . NOT NULL means that the column can not have a NULL value for any record; NULL means NULL is an allowable value (even when the column has a foreign key constraint).


Dated : 21-Jul-2022

Category : Education