1. Execute following statement: 
"CREATE TABLE animals (
     id MEDIUMINT NOT NULL AUTO_INCREMENT,
     name CHAR(30) NOT NULL,
     PRIMARY KEY (id)
 );"
2. Refresh "Tables" node, rightclick animals and choose "View Data".
3. Press "Insert a record." button.
4. Enter string 'dog' for "name" field and click "Execute".

Result: Message "Please enter valid values for not nullable columns" appears and record isn't inserted. Field "id" isn't
editable.