SQL NULL Vs EMPTY Statement

The major distinction between NULL refers to nothing, whereas EMPTY refers to a single string of zero length.

A string is a collection of characters. "Programming," for example, is a String .

Strings are supported by the Java programming language and are considered as objects.

The String class is unchangeable.

As a result, once an item is created, it cannot be modified. Strings can be null or empty at times.

When you assign null to a String variable, it means the variable isn't actually referring to any memory location in the heap.

The assignment of an empty String to a String variable, on the other hand, implies that the reference variable is pointing to a memory address of a String of zero length .

SQL NULL Statement

Nothing is referred to as null. NULL indicates that we have no idea what the value is; it may or may not exist; we just don't know. Take note of the following two statements.

The variable s1 is a String. It's been given the value of null. As a result, the JVM will not allocate any memory, and the variable s1 will be null.

String s1 = null;

this is also equivalent to String s1; When printing function does not count the length of a string.

Example: Let's start by looking at an example that shows how to use the IS NULL condition in a SELECT statement.

In this example, we have a table called Country with the following data:

ID	Code	Name	Continent
1	TJK	Tajikistan	Asia
2	SYR	Syria	Asia
3	MYS	Malaysia	Asia
4	FRA	France

Enter the following SQL statement:

//Mysql,Sql-server,Sqlite,Ms access

SELECT *
FROM Country
WHERE Continent IS NULL;

When testing for a NULL value, IS NULL is the recommended comparison operator to use in SQL. There will be 1 record selected.

Output: This example will return all records from the Country table where the Continent contains a NULL value.

ID	Code	Name	Continent
4	FRA	France

SQL EMPTY

Empty-String denotes that we are aware of the value and that it is zero. The term "empty" refers to a string that has no length. Please see the code below.

The variable s2 is a String. It is given the value "" as an empty string.

As a result, the JVM will set aside memory for an empty string. That empty string will be referred to by s2.

It will print 0 when the length of the String s2 is printed.

This is because s1 refers to a String, but there are no characters in it to count the length.

SQL DIFFERENCE BETWEEN NULL AND EMPTY FUNCTION

In below table we will discusse the distinguish between null & empty function:-

Column 1	Column 2
NULL is a phrase used to denote that an object refers to nothing on the heap.	EMPTY is a word that denotes that an object refers to a single zero-length string in the heap.
A null pointer exception will be thrown if the length of the null string is printed.	If you print the length of an empty string, you'll get a zero.
Null can refer to an unknown value or a value that does not exist.	An empty or blank string is a value that is just that: it is empty.
Null can be used to represent a string, an integer, a date, or any other field in a database.	For string fields, the value empty is used.
Because NULL is an unknown value, no memory is allocated to a field with NULL.	EMPTY fields have no value and are assigned memory space.
If you don't allow empty strings but don't require the user to enter a value, NULL is a good option.	If you need a value but it can be empty, `NOT NULL` is appropriate, and a value of "" is appropriate.

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