Question

I have a table with way too many columns and a couple million rows that I need to query for differences.

On these rows there will hopefully be only one column that is different and that should be the Auto incremented id field.

What I need to do is check to see if these rows ARE actually the same and if there are any that have any differences in any of the fields.

So for example, if the “Name” column is supposed to be “Peter, Paul and Mary” and the “Order #” column is supposed to be “132” I need to find any rows where those values aren’t true, but I need to find it for every column in the table AND I don’t actually know what the correct values are (meaning I can’t just create a “SELECT…WHERE Name=’This'” for each column).

So how can I find the rows that are different? (using straight SQL, no programming)

Answer 1

Would you think this answer is what you are looking for and would help you? here’s a Link to find the appropriate sql query.

Let’s suppose you coded a email newsletter signup form, but you forgot to double check that the email address was not a duplicate, or already in the database. We can write a query to find all the emails in our table that are duplicates, or occurs in more than one row.

The following SQL query works great for finding duplicate values in a table.

SELECT email, 
 COUNT(email) AS NumOccurrences
FROM users
GROUP BY email
HAVING ( COUNT(email) > 1 )

By using group by and then having a count greater than one, we find rows with with duplicate email addresses using the above SQL.
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