Convert varchar to float IF ISNUMERIC

Question

I have a column that contains characters and numbers

12
13
14
19K/YR
22

So the column type is varchar. But then I'm also doing some computations with this column, so I'm trying to convert the data to float if it is numeric.

This gives me an error though:

SELECT CASE ISNUMERIC(QTY) 
         WHEN 1 THEN CAST(QTY AS float) 
         ELSE QTY 
       END AS test

Answer 1

You can't cast to float and keep the string in the same column. You can do like this to get null when isnumeric returns 0.

SELECT CASE ISNUMERIC(QTY) WHEN 1 THEN CAST(QTY AS float) ELSE null END