Error converting data type varchar

Question

I currently have a table with a column as varchar. This column can hold numbers or text. During certain queries I treat it as a bigint column (I do

Answer 1

Try using this:

SELECT 
  ID, 
  CAST(MyCol AS bigint) as MyCol
FROM
(
  SELECT TOP (100) PERCENT 
      ID, 
      MyCol 
  FROM 
      MyTable 
  WHERE 
      (isnumeric(MyCol) = 1)
) as tmp

This should work since the inner select only return numeric values and the outer select can therefore convert all values from the first select into a numeric. It seems that in your own code SQL tries to cast before executing the isnumeric function (maybe it has something to do with optimizing).

Answer 2

Try doing the select in 2 stages.

first create a view that selects all columns where my col is nummeric.

Then do a select in that view where you cast the varchar field.

The other thing you could look at is your design of tables to remove the need for the cast.

EDIT

• Are some of the numbers larger than bigint?
• Are there any spaces, leading, trailing or in the number?
• Are there any format characters? Decimal points?