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I have a table software and columns in it as dev_cost, sell_cost. If dev_cost is 16000 and sell_cost is 7500, how do I find the quantity of software to be sold in order to recover the dev_cost?

I have queried as below:

select dev_cost / sell_cost from software ;

It is returning 2 as the answer. But we need to get 3, right?

What would be the query for that?

cottontail
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zeewagon
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4 Answers4

276

Your columns have integer types, and integer division truncates the result towards zero. To get an accurate result, you'll need to cast at least one of the values to float or decimal:

select cast(dev_cost as decimal) / sell_cost from software ;

or just:

select dev_cost::decimal / sell_cost from software ;

You can then round the result up to the nearest integer using the ceil() function:

select ceil(dev_cost::decimal / sell_cost) from software ;

(See demo on SQLFiddle.)

Ilmari Karonen
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  • We're talking about money. Cast to decimal, not float. – Mike Sherrill 'Cat Recall' Dec 29 '15 at 04:47
  • @Mike: Good point, although unlikely to matter in the OP's case. (All they're asking for is integer division that rounds up; floats will do just fine as an intermediate type for that, at least unless the original values are bigints.) Still, fixed. – Ilmari Karonen Dec 29 '15 at 04:56
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    @MRah: Glad to be of assistance. :) BTW, instead of commenting on answers that you find useful, you can vote them up by clicking the upwards-pointing triangle icon in the top left corner of the answer. This will reward the answerer with reputation points and lets them know that their answer is appreciated, and it also [helps the best answers rise to the top of the page.](http://stackoverflow.com/help/why-vote) – Ilmari Karonen Jan 09 '17 at 21:45
12

You can cast integer type to numeric and use ceil() function to get the desired output

The PostgreSQL ceil function returns the smallest integer value that is greater than or equal to a number.

SELECT 16000::NUMERIC / 7500 col 
      ,ceil(16000::NUMERIC / 7500)

Result:

col                  ceil 
------------------   ---- 
2.1333333333333333     3

So your query should be

select ceil(dev_cost::numeric/sell_cost) 
from software
Vivek S.
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10

You can also cast your variable to the desired type, then apply division:

 SELECT (dev_cost::numeric/sell_cost::numeric);

You can round your value , and specify the number of digits after point:

SELECT TRUNC((dev_cost::numeric/sell_cost::numeric),2);
AdagioDev
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1

This query will round result to next integer 

select round(dev_cost ::decimal / sell_cost + 0.5)
Abylay Sabirgaliyev
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  • This will give the wrong result if `dev_cost` happens to be an integer multiple of `sell_cost`: [see example](http://sqlfiddle.com/#!15/56439/1/0). – Ilmari Karonen Dec 29 '15 at 05:02
  • This query is ok. But if the table more values, say for example, dev_cost is 6000 and sell_cost is 400, the answer 15 would be correct. But your query gives 16 as the answer. What should we do? I am new to SQL, correct me if I am wrong. – zeewagon Dec 29 '15 at 05:44
  • Either round() or floor(x + 0.5), but not round(x + 0.5) – J. B. Rainsberger Apr 17 '22 at 13:26