How to convert a column wit varchar(max) in int

Question

I have the following problem:

I have a table ArticleDescription with columns like this:

ID (int)            Description (varchar(max))
1                   Muller Bogen, chrome-14440416700-55
2                   Muller Bogen, chrome-14440416700-55
3                   Muller Geruchverschluss 1 1/4¨, black-11188870-00
                    Muller Ma.02 Waschtisch-Wand-Einhandbatterie ohne Ablaufgarnitur, white-12345678-08

I only want to convert the datatype of the column Description to int.

I have tried:

SELECT (case when isnumeric(Description) = 1 then cast(Description as int) end)
FROM   ArticleDescription

But I get the following message:

Meldung 245, Ebene 16, Status 1, Zeile 20 Fehler beim Konvertieren des varchar-Werts "Dornbracht Bogen-04240418900-00" in den int-Datentyp.

Answer 1

Data columns must all be of the same type. In order to do this, you will need to have an acceptable alternative value for the remainder of the rows.

declare @foo table(
    ID int,
    Description varchar(20) null
)

insert into @foo
values(1,'one')
,(2,'2')
,(3,'')
,(4,null)

select 
ID,
CASE WHEN ISNUMERIC(Description) = 1 then CAST(Description as INT) ELSE null END as [Parsed Description]
from @foo

or you can add a where clause to only select numeric descriptions

select 
ID,
CAST(Description as INT)  as parsed_pescription
from @foo foo
where ISNUMERIC(Description) = 1