Question

The table contains numerous rows for the same person and all columns contain the same data. For Instance:

FullName       Gender     DOB
---------------------------------
Mary Jones     Female     2012-05-01

I would like to select one row for each individual to appear in a report. I thought the easiest way might be to us an if statment to check if the next row is the same as the first unique row.

Answer 1

As others have said, since all the rows are the same you can use the distinct keyword:

SELECT DISTINCT <columns>
FROM table

However, you’re likely to find that the reason for these duplicate records is that at least one column somewhere in the table is different. In that case, you may need to use GROUP BY instead:

SELECT <columns>
FROM table
GROUP BY <columns>

If you need to show data that is not part of the grouped columns, you only list the columns that match in the GROUP BY clause and then you have to use an aggregate function or sub query to bring data from the unique columns into the select list. GROUP BY queries can get really complex and make your head hurt.

If the columns really are consistently the same, something in your schema or application design isn’t right. It’s rare that you should ever have truly duplicate records in a table, and it’s more likely to mean something is wrong.

Finally, I need to comment about your IF/THEN request. This idea is way off. SQL has a SET-based or declarative programming style. Thinking about problems using procedural tools like IF/THEN will only lead to trouble. Even if you really do need a conditional expression, the way to do it within an SQL statement is via a CASE expression.