mysql – SQL – How to select or exclude a column with value equal to null in a select query

Question:

I have a table in a MySQL database that has 5 fields. This would be a model query:

select * from myTable where campo1= 4 and campo2=1 and campo3 =7.

However, field3 can have a null value and I would need to select or exclude combinations that involve this value.

Example1:

select * from myTable where campo1= 4 and campo2=1 and campo3 = null.

Example2:

select * from myTable where campo1= 4 and campo2=1 and campo3 <> null.

The problem is that these two examples don't work. I've tried using "null" and 'null' but I can't select.

Any idea?

In case campo3 = null and you don't want to show it:

select * from myTable where campo1= 4 and campo2=1 where campo3 is not null

In case you want to show only when campo3<>null :

select * from myTable where campo1= 4 and campo2=1 where campo3 is null

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