是否可以在保持小数形式的同时在 SQL 中舍入小于 1 的数字

Question

I am not finding the solution to this issue despite looking specifically for it.

The below query is me trying to get the last decimal places to appear properly.

select CAST(CAST(33 as float)/100 as decimal(5,3))

From here I am looking for how to round properly to .33 or if the result were .339 to round up to .34

What I am finding is that it will only round down to 0 because it is not a whole number.

Can someone point me in the right direction or if there is no good way let me know.

Answer 1

Make sure your denominator isn't treated as an integer. You could tack on a .0 or CAST or CONVERT it. In the case where you'd expect rounding down to occur:

SELECT 331 / 1000.0;
-- gives 0.331000

SELECT ROUND(331 / 1000.0, 2);
-- gives 0.330000

SELECT CAST(ROUND(331 / 1000.0, 2) AS DECIMAL(5, 2));
-- gives 0.33

In the case where you'd be expect rounding up to occur:

SELECT 339 / 1000.0;
-- gives 0.339000

SELECT ROUND(339 / 1000.0, 2);
-- gives 0.340000

SELECT CAST(ROUND(339 / 1000.0, 2) AS DECIMAL(5, 2));
-- gives 0.34

Note: you may not need to do both ROUND and CAST since I believe the rounding occurs implicitly, but it makes the intent more clear if you choose to write it as such.

Answer 2

You can try this:

MySQL:

select ROUND(339/1000,2)
0.34

select ROUND(33/100,2)
0.33

SQL Server:

select ROUND(339/1000.0,2)
0.340000

select ROUND(33/100.0,2)
0.330000