Question: How to make sure that field is mandatory ? Here is what I mean

I have the following mysql table structure:

```
CREATE TABLE `new` (
  `id` int(11) DEFAULT NULL,
  `name` int(11) DEFAULT NULL,
  `phone` int(11) NOT NULL
) ENGINE=MyISAM DEFAULT CHARSET=latin1;

```

Here is query with no data for phone

```
insert into new values(1, 'm', '');

```

But the query runs fine. What should be done so that mysql returns an error if there is no data for phone field? I can do that validation by php, but I'm curious how to do that in mysql.

Answer: 
```
INSERT INTO new VALUES(1,'m',NULL)

```

will cause error.  

If you want to check whether is the phone number field is a blank string,  

you can use a trigger in MySQL.
'' as the 3rd option doesnt make the value of phone null.. It is just equal to a blank string thats all.
if you want to see an error, replace '' with NULL.