Why having NULL values in your database is a problem?

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Why having NULL values in your database is a problem?

33 Answers. Nulls are negatively viewed from the perspective of database normalization. The idea being that if a value can be nothing, then you really should split that out into another sparse table such that you don’t require rows for items which have no value. It’s an effort to make sure all data is valid and valued.

What does a null value represent in a database?

The SQL NULL is the term used to represent a missing value. A NULL value in a table is a value in a field that appears to be blank. A field with a NULL value is a field with no value. It is very important to understand that a NULL value is different than a zero value or a field that contains spaces.

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When NULL is used in a SQL statement it is treated as?

SQL Server treats null values as being equal in context of unique constraints: only one null is allowed per column.

Can database have NULL values?

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 purpose of null character?

A null character is a character with all its bits set to zero. Therefore, it has a numeric value of zero and can be used to represent the end of a string of characters, such as a word or phrase. This helps programmers determine the length of strings.

How are nulls treated when aggregate functions are applied in an SQL query?

How are NULLs treated when aggregate functions are applied in an SQL query? They are separated into a group created for all tuples with a NULL value in grouping attribute.

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How is NULL stored in database?

It stores an array of bits (one per column) with the data for each row to indicate which columns are null and then leaves the data for that field blank.

Is NULL the same as blank?

NULL means the absence of any value. You can’t do anything with it except test for it. Blank is ill-defined. It means different things in different contexts to different people.