For Back up I have used the following commands.
mysqldump -u root -p[root_password] [database_name] > dumpfilename.sql
mysqldump -u [username] -p[root_password] --single-transaction
--routines --triggers --lock-tables [database_name] > backup.sql;
Getting same error:
mysqldump: Couldn't execute 'show table status like 'uc_order_products_pair_vw'': SELECT command denied to user 'username'@'localhost' for column 'nid' in table 'uc_order_products' (1143)
After running select * from mysql.tables_priv;