How to update multiple rows in one query using php

Question

i am new to this can any one help me how to update multiple rows at a time i am doing an school attendance page

Answer 1

Often the situation is such that you have multiple courses across a range of dates.So students may take more than one course, and you need to track attendance for each course date. The following graphic demonstrates this:
In such a situation, you need four database tables as follows:
students (student_id, student_name, etc.)
courses (course_id, course_name, etc.)
students_courses (student_id, course_id)
attendance (student_id, course_id, dater)
A fifth table may also be needed to define the dates of courses, but you may also be able to build this array programmatically by using PHP's robust date functions, which can give you, for instance, all the Tuesdays and Thursdays between a start date and end date.
The students_courses table simply keeps track of which students are taking which courses, so it has just two columns for the primary keys of both of the main tables. The attendance table is similar, but it also includes a date field. The following view of the attendance table demonstrates this:
So if David's solution does cover your needs, consider yourself lucky, because this could quickly grow from a beginner-appropriate project to a moderately advanced one.