SQL select from data in query where this data is not already in the database?

Question

I want to check my database for records that I already have recorded before making a web service call.

Here is what I imagine the query to look like, I just can\'t

Answer 1

Use:

   SELECT x.id
     FROM (SELECT @param_1 AS id
             FROM DUAL
           UNION ALL
           SELECT @param_2
             FROM DUAL
           UNION ALL
           SELECT @param_3
             FROM DUAL
           UNION ALL
           SELECT @param_4
             FROM DUAL) x
LEFT JOIN TABLE t ON t.id = x.id
    WHERE x.id IS NULL

If you need to support a varying number of parameters, you can either use:

• a temporary table to populate & join to
• MySQL's Prepared Statements to dynamically construct the UNION ALL statement