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My goal is two divide two integers in Presto 0.212, e. g. 1/2. The naive approach SELECT 1/2 returns 0. Next, I tried SELECT CAST(1/2 AS DOUBLE), but this also returns 0. How to divide 1/2 such that 0.5 is returned?

Joe
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1 Answers1

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I'm not familiar with Presto, but my guess is that in the example you've provided 1/2 is being evaluated as an integer then is being cast as a double. Maybe something along the lines of SELECT CAST(1 AS DOUBLE)/CAST(2 AS DOUBLE) or you maybe you could just add .0 to the end of your numbers like SELECT 1.0/2.0. Just a few shots in the dark from me.

glenjaminlatrobe
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  • Both work, but as I want to divide columns I choose the first one. – Joe Dec 04 '18 at 19:42
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    In Presto (following SQL standard), `2.0` is not a `double`, it's of `decimal(2,1)` type. This affects results: `10 / 3e0` prints `3.3333333333333335`, while `10 / 3.0` prints `3.3`. Use scientific notation or explicit type construct to get "2 as double": `2e0` or `double '2'`. – Piotr Findeisen Dec 05 '18 at 07:43