Page 240 - Open Soource Technologies 304.indd

Unit 14: Connecting to MySQL with PHP

The CREATE TABLE statement for the student table look like this Notes

mysql>CREATE TABLE student
(

roll_no INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY ,
name VARCHAR(20) NOT NULL,

specialization VARCHAR(6) NOT NULL,

dob DATE NOT NULL);
In the above insert statement:

• INT signifies that the column holds integers (value with no fractional part).
• UNSIGNED disallows negative numbers.

• NOT NULL means that the column value must be filled in. (No student can be without
a roll number).

• AUTO_INCREMENT works like this: If the value for the roll_no column is missing
(or NULL) when you create a new student table record, MySQL automatically generates
a unique number that is one greater than the maximum value currently in the column.

• PRIMARY KEY means each value in the column must be unique. This prevents us for using
the roll number twice by mistake, which is desirable property for student roll number.
(Not only that, but MySQL requires every AUTO_INCREMENT column have a unique
index).
• VARCHAR(n) means the column contains variable-length character values, with a
maximum length of n characters.
• Column type DATE holds the value in the format “YYYY-MM-DD”(for example,”
1983-10-24”)

LOVELY PROFESSIONAL UNIVERSITY 235