What is Null?

Null, in a Database Context, is the full absence of a price in a positive discipline and means that the sector price is unknown. Null isn't always the same as a zero value for a numerical area, text subject or area value. Null implies that a Database Field cost has now not been saved.

What Does Null Mean?

A null can not be as compared to a value. For example, if a question is directed to a Customer_Addresses Table to retrieve all Clients without e-mail addresses, then the Structured Query Language (SQL) question cannot be written as follows: SELECT * FROM Customer_ Addresses WHERE Email_Address=null. Instead, in order not to introduce a assessment with a null, the Query have to be written as follows: SELECT * FROM Customer_ Addresses WHERE Email_Address IS null.

When the values in a column containing nulls are counted, nulls aren't Protected in the outcomes. For example, there are 200 customers inside the Customer_ Addresses table, and 30 have nulls inside the Email_Address column. Doing a be counted using the Email_Address column will return a result of one hundred sEventy.