Automatically Increment ID

[Dysan]

I have the following code that creates a table.
Can the ID field be made as an auto-incrementing field?

mysql_select_db("DB", $con);
$sql = "CREATE TABLE Data 
(
ID int,
Firstname text,
Lastname text,
Age int,

)";
mysql_query($sql,$con);

[NogDog]

ID INT AUTO_INCREMENT PRIMARY KEY,

However, I would also recommend the following changes:

CREATE TABLE Data 
(
ID INT UNSIGNED AUTO_INCREMENT PRIMARY KEY,
Firstname VARCHAR(30) NOT NULL,
Lastname VARCHAR(30) NOT NULL,
Age TINYINT UNSIGNED NOT NULL
)

(Change the NOT NULL to NULL on any field for which null values are to be allowed. Change the "(30)" values to whatever max length you want to impose on those name columns.)

[Dysan]

What does the unsigned bit mean?

[bradgrafelman]

It extends the range of the values accepted from -2147483648 through 2147483647 to 0 through 4294967295. Obviously, UNSIGNED means that the values are sign-less - there are no negative values accepted.

For more information on numeric column types, see this page in the MySQL manual.