NOT NULL in SQL.txt

// NOT NULL
-> By default a tables column can hold NULL values.
The NOT NULL constraint enforces a field to always contain a vlaue. This means that you cannot insert a new record, or update a record without 
adding a value to this field.
ex:create table example(name varchar (30),roll int (10), number int(10)
NOT NULL);

// output
desc example;
+--------+-------------+------+-----+---------+-------+
| Field  | Type        | Null | Key | Default | Extra |
+--------+-------------+------+-----+---------+-------+
| name   | varchar(30) | YES  |     | NULL    |       |
| roll   | int         | YES  |     | NULL    |       |
| number | int         | NO   |     | NULL    |       |
+--------+-------------+------+-----+---------+-------+

msg :  INSERT INTO example (name,roll) VALUES('Ram',10);
ERROR 1364 (HY000): Field 'number' doesn't have a default value
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