What is the role of NOTNULL in the statement 'AAA' varchar (11) NOTNULL when creating a field? What is the function of the statement 'AAA' & nbsp; varchar (11) & nbsp; NOT & nbsp; NULL in "NOT & nbsp; NULL" when creating a field? NOT & nbsp; NULL? ------ Solution ------------------ what is the role of not null in the statement 'AAA' varchar (11) not null when creating a field?
When creating a field, what is the function of the statement 'AAA' varchar (11) not null?
Not null?
------ Solution ----------------------
This field cannot be blank (null). That is, when a record is inserted, this field must have a value.
Not null? Yes, of course, but it depends on your business.
------ Solution ----------------------
Not null indicates that this field cannot be null when you insert it.
Remember, null is different from null. the null string is :''
The database can declare not null default''
In this case, data is inserted. if this field is not declared, it is stored as a null string by default.
There are many reasons for not null. one of the reasons is that a field in the database is null, which indicates null, the string is null after you obtain it.
------ Solution ----------------------
When inserting data, the field cannot be blank and must have a value.
