Collectives™ on Stack Overflow
Find centralized, trusted content and collaborate around the technologies you use most.
Learn more about Collectives
Teams
Q&A for work
Connect and share knowledge within a single location that is structured and easy to search.
Learn more about Teams
I have a float column with numbers of different length and I'm trying to convert them to varchar.
Some values exceed bigint max size, so I can't do something like this
cast(cast(float_field as bigint) as varchar(100))
I've tried using decimal, but numbers aren't of the same size, so this doesn't help too
CONVERT(varchar(100), Cast(float_field as decimal(38, 0)))
Any help is appreciated.
UPDATE:
Sample value is 2.2000012095022E+26.
Another note: this pads on the left with spaces. If this is a problem combine with LTRIM:
SELECT LTRIM(STR(float_field, 25, 5))
–
–
–
The only query bit I found that returns the EXACT same original number is
CONVERT (VARCHAR(50), float_field,128)
See http://www.connectsql.com/2011/04/normal-0-microsoftinternetexplorer4.html
The other solutions above will sometimes round or add digits at the end
UPDATE: As per comments below and what I can see in https://msdn.microsoft.com/en-us/library/ms187928.aspx:
CONVERT (VARCHAR(50), float_field,3)
Should be used in new SQL Server versions (Azure SQL Database, and starting in SQL Server 2016 RC3)
–
–
–
–
this is the solution I ended up using in sqlserver 2012 (since all the other suggestions had the drawback of truncating fractional part or some other drawback).
declare @float float = 1000000000.1234;
select format(@float, N'#.##############################');
output:
1000000000.1234
this has the further advantage (in my case) to make thousands separator and localization easy:
select format(@float, N'#,##0.##########', 'de-DE');
output:
1.000.000.000,1234
–
–
–
–
select @test
set @test1 = convert (decimal(10,5), @test)
select cast((@test1) as varchar(12))
Select LEFT(cast((@test1) as varchar(12)),LEN(cast((@test1) as varchar(12)))-1)
Returns nvarchar if one of the input arguments is of the nvarchar data type; otherwise, REPLACE returns varchar.
Returns NULL if any one of the arguments is NULL.
tests:
null ==> [NULL]
1.11 ==> 1.11
1.10 ==> 1.1
1.00 ==> 1
0.00 ==> 0
-1.10 ==> -1.1
0.00001 ==> 1e-005
0.000011 ==> 1.1e-005
If you use a CLR function, you can convert the float to a string that looks just like the float, without all the extra 0's at the end.
CLR Function
[Microsoft.SqlServer.Server.SqlFunction(DataAccess = DataAccessKind.Read)]
[return: SqlFacet(MaxSize = 50)]
public static SqlString float_to_str(double Value, int TruncAfter)
string rtn1 = Value.ToString("R");
string rtn2 = Value.ToString("0." + new string('0', TruncAfter));
if (rtn1.Length < rtn2.Length) { return rtn1; } else { return rtn2; }
Example
create table #temp (value float)
insert into #temp values (0.73), (0), (0.63921), (-0.70945), (0.28), (0.72000002861023), (3.7), (-0.01), (0.86), (0.55489), (0.439999997615814)
select value,
dbo.float_to_str(value, 18) as converted,
case when value = cast(dbo.float_to_str(value, 18) as float) then 1 else 0 end as same
from #temp
drop table #temp
Output
value converted same
---------------------- -------------------------- -----------
0.73 0.73 1
0 0 1
0.63921 0.63921 1
-0.70945 -0.70945 1
0.28 0.28 1
0.72000002861023 0.72000002861023 1
3.7 3.7 1
-0.01 -0.01 1
0.86 0.86 1
0.55489 0.55489 1
0.439999997615814 0.439999997615814 1
Caveat
All converted strings are truncated at 18 decimal places, and there are no trailing zeros. 18 digits of precision is not a problem for us. And, 100% of our FP numbers (close to 100,000 values) look identical as string values as they do in the database as FP numbers.
Modified Axel's response a bit as it for certain cases will produce undesirable results.
DECLARE @MyFloat [float];
SET @MyFloat = 1000109360.050;
SELECT REPLACE(RTRIM(REPLACE(REPLACE(RTRIM((REPLACE(CAST(CAST(@MyFloat AS DECIMAL(38,18)) AS VARCHAR(max)), '0', ' '))), ' ', '0'),'.',' ')),' ','.')
DECLARE @F FLOAT = 1000000000.1234;
SELECT @F AS Original, CAST(FORMAT(@F, N'#.##############################') AS VARCHAR) AS Formatted;
SET @F = 823399066925.049
SELECT @F AS Original, CAST(@F AS VARCHAR) AS Formatted
UNION ALL SELECT @F AS Original, CONVERT(VARCHAR(128), @F, 128) AS Formatted
UNION ALL SELECT @F AS Original, CAST(FORMAT(@F, N'G') AS VARCHAR) AS Formatted;
SET @F = 0.502184537571209
SELECT @F AS Original, CAST(@F AS VARCHAR) AS Formatted
UNION ALL SELECT @F AS Original, CONVERT(VARCHAR(128), @F, 128) AS Formatted
UNION ALL SELECT @F AS Original, CAST(FORMAT(@F, N'G') AS VARCHAR) AS Formatted;
I just came across a similar situation and was surprised at the rounding issues of 'very large numbers' presented within SSMS v17.9.1 / SQL 2017.
I am not suggesting I have a solution, however I have observed that FORMAT presents a number which appears correct. I can not imply this reduces further rounding issues or is useful within a complicated mathematical function.
T SQL Code supplied which should clearly demonstrate my observations while enabling others to test their code and ideas should the need arise.
WITH Units AS
SELECT 1.0 AS [RaisedPower] , 'Ten' As UnitDescription
UNION ALL
SELECT 2.0 AS [RaisedPower] , 'Hundred' As UnitDescription
UNION ALL
SELECT 3.0 AS [RaisedPower] , 'Thousand' As UnitDescription
UNION ALL
SELECT 6.0 AS [RaisedPower] , 'Million' As UnitDescription
UNION ALL
SELECT 9.0 AS [RaisedPower] , 'Billion' As UnitDescription
UNION ALL
SELECT 12.0 AS [RaisedPower] , 'Trillion' As UnitDescription
UNION ALL
SELECT 15.0 AS [RaisedPower] , 'Quadrillion' As UnitDescription
UNION ALL
SELECT 18.0 AS [RaisedPower] , 'Quintillion' As UnitDescription
UNION ALL
SELECT 21.0 AS [RaisedPower] , 'Sextillion' As UnitDescription
UNION ALL
SELECT 24.0 AS [RaisedPower] , 'Septillion' As UnitDescription
UNION ALL
SELECT 27.0 AS [RaisedPower] , 'Octillion' As UnitDescription
UNION ALL
SELECT 30.0 AS [RaisedPower] , 'Nonillion' As UnitDescription
UNION ALL
SELECT 33.0 AS [RaisedPower] , 'Decillion' As UnitDescription
SELECT UnitDescription
, POWER( CAST(10.0 AS FLOAT(53)) , [RaisedPower] ) AS ReturnsFloat
, CAST( POWER( CAST(10.0 AS FLOAT(53)) , [RaisedPower] ) AS NUMERIC (38,0) ) AS RoundingIssues
, STR( CAST( POWER( CAST(10.0 AS FLOAT(53)) , [RaisedPower] ) AS NUMERIC (38,0) ) , CAST([RaisedPower] AS INT) + 2, 0) AS LessRoundingIssues
, FORMAT( POWER( CAST(10.0 AS FLOAT(53)) , [RaisedPower] ) , '0') AS NicelyFormatted
FROM Units
ORDER BY [RaisedPower]
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
