如何在SQL的行中查找重复项？

Question

I see lot's of questions and answers about duplicate rows, but mine is different.

I have a table with 15 columns that should be unique with respect to each other, so within a row these 15 fields should all have different values.

How can I check this, or more precisely, I want to select all the rows that do have one or more duplicate values within those 15 fields.

Any pointers?

Answer 1

You can use a giant where condition:

where col1 in (col2, col3, . . . , col15) or
      col2 in (col3, col4, . . ., col15) or
      col14 in (col15)

This assumes that none of the values are NULL .

You should probably fix the data structure. The data in the 15 columns should probably be in 15 rows in a junction table.