I have an attribute table where 2 columns have values in common. What I need is to Select by attributes the rows that have the same values, for this I'm doing:

"w_min"= "MIN_W_MIN" AND "MIN_W_MIN" <> 0

Because I want to select the rows that have the same values in field w_min and field MIN_W_MIN.

What's happening is that it's not selecting those rows and I don't know why. It only select the rows that have 0 in this two fields. Because of that I put the query MIN_W_MIN <> 0

What could be the cause of that failure in selection?

1 Answer 1


What can cause the failure is that the two fields have not the same data type (ex : : integer and text). You could for example have NULL or "" values hidden. What I suggest :

  • Check datatypes of the two columns

  • If similar, select "MIN_W_MIN" <> 0 - see if it works

  • Select "w_min"= "MIN_W_MIN" - see if it works

  • If not similar, create new columns to match the right datatype (integer or float ?) then retry previous tests.

When both tests are passed, you should be able to run a single query or rerun a query on the result of the first query to mimic the clause AND.

  • w_min is float and MIN_W_MIN is double. Is this the cause?
    – AndM
    Sep 17, 2015 at 10:32

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