Convert VarChar to Float with different culture format - sql

Question

From different external sources I get data where some numbers are in a NVarChar field. Until now I used a REPLACE with a CAST to ensure that numbers with a "," where cast the right way. Like this:
select cast(replace('12,5',',','.') as float)
select cast(replace('12.5',',','.') as float)
This has worked just fine, but now I get data where there is also a thousand separator in. Like this:
select cast(replace('2.012,5',',','.') as float)
select cast(replace('2,012.5',',','.') as float)
It' broken.
Is there a way to detect which data format is used in a NVarChar with a number?
I have tried to use TRY_PARSE with a culture parameter, it works well if there is a thousand separator but not without:
SELECT #Fuelunits =
CASE
WHEN ISNUMERIC(TRY_PARSE(#Hoeveelheid AS decimal(9,2) USING 'nl-NL')) = 1
THEN CAST(TRY_PARSE(#Hoeveelheid AS decimal(9,2) USING 'nl-NL') AS FLOAT)
ELSE CAST(TRY_PARSE(#Hoeveelheid AS decimal(9,2) USING 'en-US') AS FLOAT)
END
The problem is that I have to use this in an UPDATE and that that the data format can differ in the same table.
Any suggestions?

Answer 1

You can use CHARINDEX() to work out what separators are present and where they are in the string along with a CASE expression to handle different cases before you REPLACE and CAST to FLOAT:
CREATE TABLE #vals (val NVARCHAR(10));
INSERT INTO #vals
(
val
)
VALUES
(N'2.012,5'),
(N'2,012.5');
SELECT CAST(CASE
-- is there a '.' in a position before a ','?
WHEN CHARINDEX('.', val) < CHARINDEX(',', val) THEN
-- yes - remove the '.' and replace the ',' with '.'
REPLACE(REPLACE(val, '.', ''), ',', '.')
ELSE
-- no - just remove the ','
REPLACE(v.val, ',', '')
END AS FLOAT)
FROM #vals AS v;
DROP TABLE #vals;
References:
CHARINDEX (Transact-SQL)
Searches an expression for another expression and returns its starting position if found.