Insert into a table with a select statement in mysql

Question

I have a table that has training history that has been modified by many different users over the years. This has cause the same training record to be entered twice. I want to create a table that replicates the main table and insert all duplicate records.

What constitutes a duplicate record is if the employee_id, course_code, and completion_date all match.

I can create the duplicate table and I have a select statement that appears to pull duplicates, but it pulls only one of them and I need it to pull both (or more) of them. This is because one person may have entered the training record with a different course name but the id, code, and date are the same so it is a duplicate entry. So by pulling all the duplicates I can validate that that is the case.

Here is my SELECT statement:

SELECT * 
FROM 
    training_table p1
JOIN 
    training_table p2 ON (
        p1.employee_id = p2.employee_id
        AND p1.course_code = p2.course_code
        AND p1.completion.date = p2.completion_date)
GROUP BY p1.ssn;

The query runs and returns what appear to be unique rows. I would like all of the duplicates. And whenever I try to INSERT it into an identical table I get an error stating my column count doesn't match my value count.

Any help would be great.

Answer 1

This will select any duplicate rows for insertion into your new table.

SELECT p1.* 

FROM   training_table p1

JOIN   
       (SELECT employee_id, course_code, completion_date
        FROM   training_table 
        GROUP BY employee_id, course_code, completion_date
        HAVING COUNT(*) > 1
       ) dups 
        ON  p1.employee_id = dups.employee_id
        AND p1.course_code = dups.course_code
        AND p1.completion_date = dups.completion_date
;

Answer 2

Try to use CROSS JOIN (Cartesian Product Join) instead JOIN only. For insert try INSERT INTO TABLE (column1, column2, column3) SELECT column1, column2, column3 FROM TABLE; in same order.

Answer 3

Thanks for the help. I had discovered the answer shortly after I posted the question (even though I had looked for the answer for over an hour :) ) Here is what I used:

 SELECT  *
    FROM    training_table mto
    WHERE   EXISTS
            (
    SELECT  1
    FROM    training_table mti


    WHERE   mti.employee_id = mto.employee_ie
    AND mti.course_code = mto.course_code
    AND mti.completion_date = mto.completion_date
            LIMIT 1, 1
            )

I just added the INSERT statement and it worked. Thanks.