TSQL - Problem converting and updating a float column - tsql

Question

I have tried many ways but could not find the answer. My problem is:
there is Table ORG_DATA_AS_VARCHAR with a columnFLOATNMBRS (varchar)
FLOATNMBRS
--------------------------
0
0
*0,25 /*Yeah, there is a star in data ... bad data quality ....*/
*0,31
0
Now, my aim is to convert this strings to a float and update these new float values to a new (existing) table CONVERTED_DATA:
FLOATNMBRS (float)
--------------------------
0
0
0.25
0.31
0
...
What I have tried:
UPDATE CONVERTED_DATA
SET
FLOATNMBRS = b.newValue
FROM
(
Select convert (float, replace(replace(FLOATNMBRS, '*', ''),',','.')) as newValue from
ORG_DATA_AS_VARCHAR
) b
or
Replacing and converting it and create a #Temp Table with the new Values and Update CONVERTED_DATA with values from #Temp.
but everytime I ended up like:
FLOATNMBRS (float)
--------------------------
0
0
0
0
0
All values were updated as 0.
When I tried:
Select convert (float, replace(replace(FLOATNMBRS, '*', ''),',','.')) as newValue from
ORG_DATA_AS_VARCHAR
the result is correct. Even when I copy the value to #Temp. All values are correct.
Does someone know what I m doing wrong ???

Answer 1

You are possibly not matching the records in the 2 tables. It is not clear from your example how the rows are identified (what's the key).
Assuming you have the same ID in ORG_DATA_AS_VARCHAR and CONVERTED_DATA tables, this works:
create table #ORG_DATA_AS_VARCHAR (ID int, floatnmbrs_varchar varchar(128))
create table #CONVERTED_DATA (ID int, floatnmbrs float)
go
insert into #ORG_DATA_AS_VARCHAR (ID, floatnmbrs_varchar)
values (1, '0'), (2, '0'), (3, '*0,25'), (4, '*0.31'), (5, '0')
insert into #CONVERTED_DATA (ID, floatnmbrs)
values (1, 0), (2, 0), (3, 0), (4, 0), (5, 0)
go
update #CONVERTED_DATA
set floatnmbrs = x.converted
from (
select ID, converted = convert(float, replace(replace(floatnmbrs_varchar, '*', ''), ',', '.'))
from #ORG_DATA_AS_VARCHAR
) as x
where x.ID = #CONVERTED_DATA.ID
select * from #CONVERTED_DATA
go
drop table #ORG_DATA_AS_VARCHAR
drop table #CONVERTED_DATA
go