SQL Server 2008: Error converting data type nvarchar to float

Question

Presently troubleshooting a problem where running this SQL query:

UPDATE tblBenchmarkData 
SET OriginalValue = DataValue, OriginalUnitID = DataUnitID, 
    D         


        

Answer 1

So starting with your update query that's giving an error (please forgive me for rewriting it for my own clarity):

UPDATE B
SET
   OriginalValue = DataValue,
   OriginalUnitID = DataUnitID,
   DataValue = CAST(DataValue AS float) * 1.335
FROM
   dbo.tblBenchmarkData B
   INNER JOIN dbo.tblZEGCode Z
      ON B.ZEGCodeID = Z.ZEGCodeID
WHERE
   B.FieldDataSetID = '6956beeb-a1e7-47f2-96db-0044746ad6d5'
   AND (
      Z.ZEGCode = 'C004' OR 
      Z.ZEGParentCode LIKE 'C004%'
   )

I think you'll find that a SELECT statement with exactly the same expressions will give the same error:

SELECT
   OriginalValue,
   DataValue NewOriginalValue,
   OriginalUnitID,
   DataUnitID OriginalUnitID,
   DataValue,
   CAST(DataValue AS float) * 1.335 NewDataValue
FROM
   dbo.tblBenchmarkData B
   INNER JOIN dbo.tblZEGCode Z
      ON B.ZEGCodeID = Z.ZEGCodeID
WHERE
   B.FieldDataSetID = '6956beeb-a1e7-47f2-96db-0044746ad6d5'
   AND (
      Z.ZEGCode = 'C004' OR 
      Z.ZEGParentCode LIKE 'C004%'
   )

This should show you the rows that can't convert:

SELECT
    B.*
 FROM
    dbo.tblBenchmarkData B
    INNER JOIN dbo.tblZEGCode Z
       ON B.ZEGCodeID = Z.ZEGCodeID
 WHERE
    B.FieldDataSetID = '6956beeb-a1e7-47f2-96db-0044746ad6d5'
    AND (
       Z.ZEGCode = 'C004' OR 
       Z.ZEGParentCode LIKE 'C004%'
    )
    AND IsNumeric(DataValue) = 0
    -- AND IsNumeric(DataValue + 'E0') = 0 -- try this if the prior doesn't work

The trick in the last commented line is to tack on things to the string to force only valid numbers to be numeric. For example, if you wanted only integers, IsNumeric(DataValue + '.0E0') = 0 would show you those that aren't.