Cast from CHAR(20) to SMALLINT - response (10) by mandeep_m91

when you are dealing with char/varchar columns and trying to convert them to numbers, you might try the below to filter out alpha-numeral values
 
select *
from table_name
where upper(column) <> lower(column)
 
Where "column" is of the type char/varchar which you want to convert to integer data type.