Add 7 days to a date variable

Databases
1

I’m posting a form with a date variable in it (date_start). The posted date format is YYYYMMDD.

When writing to the datebase, I want to add 7 days to this date and write it to the date_end column.

Basically, I want to write date_end = date_start + 7 days.

I have tried several PHP and MySQL solutions, weeded through countless forum postings and not found the solution that works.

My latest try is this:

INSERT INTO table ( date_end )
VALUES (
DATE_ADD( ‘$date_start’, INTERVAL 7
DAY )

but it gives me an error:
#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘’ at line 4

My server is running PHP 4.4.9 and MYSQL 5.0.67,

Thanks for any help.

2

Echo the query and check that $date_start actually contains a value

3

Thanks, my $date_start was empty because of a typo further up in the code. Stupid mistake. Thanks for your help.