Pipeline failed for the data type


My pipeline failed due to the different data type between staging table and target table. Here is how my pipeline work:
I loaded the data from csv files into staging table, then I tried to find if the field calls “code” from staging table match the code from target table. But the data type for the field “code” from staging table is varchar2(4000) and the data type for the column in target table is char(10). It works if I setup the field “code” from staging to special value like “123” and it can find such code in target table, but it always failed if I chose the field “code” and tried to find the mapping code in target, even there is the such code in the target. I tried to use function substr(0,10) to change the data type for the column in staging, also use function toString().trim() for the column in target, it does not work. Any suggestions?