Null or NULL is a special marker used in Structured Query Language to indicate that a data value does not exist in the database.
IS null in SQL in where clause?
Generally, NULL data represents data does not exist or missing data or unknown data. IS NULL & IS NOT NULL in SQL is used with a WHERE clause in SELECT, UPDATE and DELETE statements/queries to validate whether column has some value or data does not exist for that column. Please note that NULL and 0 are not same.
How do I check if an attribute is null in SQL?
How to Test for NULL Values?
- SELECT column_names. FROM table_name. WHERE column_name IS NULL;
- SELECT column_names. FROM table_name. WHERE column_name IS NOT NULL;
- Example. SELECT CustomerName, ContactName, Address. FROM Customers. WHERE Address IS NULL; ...
- Example. SELECT CustomerName, ContactName, Address. FROM Customers.
