There are two ways to represent null values in Oracle: NULL represents missing or unknown information, which is not equal to any value. The empty string ('') represents a text value without any characters, is not equal to NULL, and can be compared with other strings.
Representation of null values in Oracle
There are two ways to represent null values in Oracle: NULL and null characters string('').
NULL
- NULL is a special value that represents missing or unknown information.
- It cannot be equal to any other value (including itself).
- In SQL statements, NULL is usually used as a placeholder to indicate that no data exists.
- For example:
SELECT * FROM table_name WHERE column_name IS NULL;
Empty string
- ##The empty string ('') represents a text value in which there is no any character.
- It is essentially a string of length 0.
- Empty strings are not equal to NULL and can be compared with other strings.
- For example:
SELECT * FROM table_name WHERE column_name = '';
Distinguish between NULL and empty string
It is very important to distinguish between NULL and empty string because they are used in SQL statements The functions in are different:- NULL is used to represent missing or unknown information.
- The empty string is used to represent a value without characters.
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