Checking for existence PHP

Question

I'm trying to check for the existence of certain data in the database before performing a function, my code looks like this at the moment. I can't seem to figure this out.

Answer 1

One option you might want to be aware of is an "upsert": Insert a new row (of the column doesn't exist); otherwise, update the existing row:

• How to Perform an UPSERT so that I can use both new and old values in update part
• How to INSERT If Row Does Not Exist (UPSERT) in MySQL

EXAMPLE:

SET @id = 1,
    @title = 'In Search of Lost Time',
    @author = 'Marcel Proust',
    @year_published = 1913;
INSERT INTO books
    (id, title, author, year_published)
VALUES
    (@id, @title, @author, @year_published)
ON DUPLICATE KEY UPDATE
    title = @title,
    author = @author,
    year_published = @year_published;

Another caveat, since you're updating your database with respect to a PHP (possibly internet-facing) app: ALWAYS use a prepared statement (as opposed to a raw SQL "insert" or "update"):

• PHP - Prepared Statements

This will help mitigate SQL injection attacks.