CODEWITHSUNDEEP
sqlt-sqlfloating-point
Vaso Miruashvili
Vaso Miruashvili

Reputation: 109

T-SQL different result on same query with float variable

Why do I get different results from this two queries?

First query:

  DECLARE @b FLOAT;
  SET @b = 100

  SELECT @b / 3 + @b / 3 + @b / 3

Second query:

  DECLARE @flt FLOAT; 
  SET @flt = 100 / 3

  SELECT @flt + @flt + @flt

I read much about float type in SQL but didn't get what is difference in this two query

(result of first one is 100 and on second 99)

Upvotes: 1

Views: 201

Answers (1)

Killer Queen
Killer Queen

Reputation: 806

It looks like the calculation is made first, then it is rounded according to the highest type. Ie.

In the first case :

First, we have performed calculations, i.e. @ b / 3 (33.33333333333) + @ b / 3 (33.33333333333) + @ b / 3 (33.3333333333333)

And now we round it, so we have 100

In the second case :

At first we have performed calculations, i.e. 100/3 ((33.33333333333)) rounded up to the highest type, i.e. rounded to 33

And now we have further calculations @ flt + @ flt + @ flt (33 + 33 + 33) so we have 99

Upvotes: 2

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