将文本或Varchar转换为十进制类型

Question

In the column [Return rate] , I have values like :

20.0%
17.1% 
etc

In my query, I want to use this values in a calculation.

So first, I replace the '%' by an empty string '' :

REPLACE([Return Rate], '%' ,'') AS [Test]

This works, and I get values like '20.0' when [Return rate] was '20.0%'.

Then I try to use this [Test] value in a calculation, for instance:

(REPLACE([Return Rate], '%' ,'') * 10) AS [Test]

But I logically obtain an error, so I try to convert this text value to perform my calculation:

CAST ( REPLACE([Current Xelus FE Return Rate], '%' ,'') AS decimal(2,1))  [Decimal Test]

And it's here that I get the error:

 Arithmetic overflow error converting varchar to data type numeric. Warning: Null value is eliminated by an aggregate or other SET operation. 

Has someone the answer to this error? Thanks a lot,

Answer 1

If any of your rows contain null values, you will get this error. Try an IsNull, like this:

CAST( 
 IsNull( 
  REPLACE([Current Xelus FE Return Rate], '%' ,'') 
 , '0.0')
AS decimal(5,1))  [Decimal Test]

If your data contains non-numeric values (as you mentioned, values like 'N/A'), you can elimimate them with the IsNumeric() function:

CAST( 
  CASE WHEN IsNumeric(
    IsNull( 
      REPLACE([Current Xelus FE Return Rate], '%' ,'') 
    , '0.0')
  ) = 1 THEN IsNull(REPLACE([Current Xelus FE Return Rate], '%' ,''),'0.0')
  ELSE '0.0' 
  END
AS decimal(5,1))  [Decimal Test]

Answer 2

Try casting it to FLOAT - decimal(2,1) is not enough:

CAST ( REPLACE([Current Xelus FE Return Rate], '%' ,'') AS FLOAT)

Then you should be able to do further calculations

CAST ( REPLACE([Current Xelus FE Return Rate], '%' ,'') AS FLOAT) * 10