select all columns with one column has different value

Question

In my table,some records have all column values are the same, except one. I need write a query to get those records. what's the best way to do it? the table is like this:

 colA  colB colC
   a     b    c
   a     b    d
   a     b    e

What's the best way to get all records with all the columns? Thanks for everyone's help.

Answer 1

Assuming you know that column3 will always be different, to get the rows that have more than one value:

SELECT Col1, Col2
FROM Table t
GROUP BY Col1, Col2
HAVING COUNT(distinct col3) > 1

If you need all the values in the three columns, then you can join this back to the original table:

SELECT t.*
FROM table t join
     (SELECT Col1, Col2
      FROM Table t
      GROUP BY Col1, Col2
      HAVING COUNT(distinct col3) > 1
     ) cols
     on t.col1 = cols.col1 and t.col2 = cols.col2

Answer 2

Just select those rows that have the different values:

SELECT col1, col2
FROM myTable
WHERE colWanted != knownValue

If this is not what you are looking for, please post examples of the data in the table and the wanted output.