Is there a difference between null and 0 in sql?

NULL and 0 are different values ​​in SQL: NULL represents an unknown or non-existent value, and 0 represents the numeric value zero. NULL cannot be compared with any value and returns NULL when participating in arithmetic operations; 0 can be compared and participated in arithmetic operations. NULL returns NULL when participating in logical operations, and 0 is considered false. NULL and numeric values ​​are handled differently in database operations, such as in conditional checks.

The difference between NULL and 0 in SQL

In SQL, NULL and 0 are two different values. Have different meanings and treatments.

Definition

• NULL: Represents an unknown or non-existent value. It is not a number or string, but a special value that means no data.
• 0: is the numeric value zero. It represents the absence of an integer or real number.

Processing

• Comparison: NULL Comparison with any value (including itself) will return NULL. This is because NULL represents an unknown value that cannot be compared with other values. On the other hand, 0 can be compared to other numeric values.
• Arithmetic operations: When NULL participates in arithmetic operations, the result will always be NULL. This is because NULL represents an unknown value and cannot participate in the calculation. On the other hand, when 0 is involved in an arithmetic operation, the result will depend on the operator.
• Logical operations: When NULL is logically operated with a Boolean value (true or false), the result will always be NULL. This is because NULL represents an unknown value whose authenticity cannot be determined. On the other hand, 0 is considered a Boolean value of false.
• Database Operations: NULL values ​​are handled differently in database operations. For example, in a conditional check, a NULL value will not match any other value. On the other hand, a value of 0 can match other numeric values.

Examples

Here are some examples that illustrate the difference between NULL and 0:

• SELECT * FROM table WHERE column IS NULL: This will return records for all rows with NULL values.
• SELECT * FROM table WHERE column = 0: This will return records for all rows with a column that has an exact value of 0.
• SELECT column 0 FROM table: This returns the column value of all rows plus 0.
• SELECT NOT column IS NULL: This will return records for all rows where the column value is not NULL.

Conclusion

Understanding the difference between NULL and 0 in SQL is critical to writing efficient and accurate SQL queries. NULL represents an unknown or non-existent value, while 0 represents the numeric value zero. The two values ​​behave differently during comparisons, arithmetic operations, logical operations, and database operations.

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