How to import an SQL file using the command line in MySQL?

Try:

mysql -u username -p database_name < file.sql

Check MySQL Options.
Note-1: It is better to use the full path of the SQL file file.sql.
Note-2: Use -R and --triggers to keep the routines and triggers of original database. They are not copied by default.
 

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A common use of mysqldump is for making a backup of an entire database:

shell> mysqldump db_name > backup-file.sql

You can load the dump file back into the server like this:
UNIX

shell> mysql db_name < backup-file.sql

The same in Windows command prompt:

mysql -p -u [user] [database] < backup-file.sql

PowerShell

C:\> cmd.exe /c "mysql -u root -p db_name < backup-file.sql"

MySQL command line

mysql> use db_name;
mysql> source backup-file.sql;

 

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mysql> use db_name;

mysql> SET autocommit=0 ; source the_sql_file.sql ; COMMIT ;