Change the length of a Column

Hi All,

I have created a table with Product_Name of Length 100 and loaded the data. Now I would like the chage the length to 20. But I am getting the error. Is it like I should drop the column, again add the column with length 20 and load the data again. Is it the only way I can do. Please advise.

alter table "Sales-Product"."PRODUCT" alter (PRODUCT_NAME NVARCHAR(20));

Error: SAP DBTech JDBC: [7] (at 45): feature not supported: cannot shorten the field length: PRODUCT_NAME: line 1 col 46 (at pos 45)