How to convert float to varchar in SQL Server

user_294554 0
Viewed 546030

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.

sql-server-2008
15 Answers
SELECT LTRIM(STR(float_field, 25, 0))

is the best way so you do not add .0000 and any digit at the end of the value.

user_67493770

Based on molecular's answer:

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;
user_86424580

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]
user_102976650
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