How do I update if exists, insert if not (AKA "upsert" or "merge") in MySQL?

Question

Is there an easy way to `INSERT` a row when it does not exist, or to `UPDATE` if it exists, using one MySQL query?

Answer 1

I use MySql almost exclusively, and for that system the query would look like this:

Insert into tablename(col1, col2, col3) values(val1,val2,val3) on duplicate key update col3=col3+1;

Other systems might have a slightly different syntax so you should check the documentation for the DBMS you are using.