What is NULL

Null is undefined value. If do not have any data for any column and we also don’t have any default value for that column, then we insert null in that column.

Example of IS NULL

Check the data of following table:-

		
records

		Figure 1

		

In this table you can see that in enq_type column we have entered null as we don’t have any value for this row.

IS NULL Operator

Now if we need to select data which is have Null in enq_type then we will use IS NULL operator in the following manner

		
		select * from enqdata where enq_type is null
		
		

After running this query it will show result as follows:-

		
isnull output

		Figure 2
		
		

IS NOT NULL Operator

Now if you want to select all data except null then we will use this operator with not in the following manner

		
select * from enqdata where enq_type is not null
		
		

and you will get following output: -

		
is not null operator

		Figure 3
		
		

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