What does mysqldump do when trying to restore a database?|

Question

I've been trying to find a good way to back up and restore a database and came upon the mysqldump . I've been using the command prompt to access the executable and I'm able to create a back up of the database in an sql file using the command:

mysqldump.exe -u [username] -p [databasename] -h localhost > [path]\backup.sql  

then I enter my password for it to execute.
Incase it wasn't understood:

[username]=my username for accessing the database  
[databasename]=my name for the database that I'm trying to back up  
[path]=the folder path to where I want to save my back up.  

With this command I'm able to create a back up and I've looked and found that the way to restore it would just be to flip the > to < so you would get this:

mysqldump.exe -u [username] -p [databasename] -h localhost > [path]\backup.sql  

then I enter my password for it to execute.
When it executes it prints out what it's dumping (doesn't create new tables if I deleted some that were supposed to be restored). I think it only adds values not already in the table since I added a row and it wasn't deleted when I tried restoring a previous version of the database.
I can execute the backup.sql file normally using a client or command prompt commands, but I just want to understand why the mysqldump isn't doing what I expect.

Answer 1

mysqldump is for backup only, you can't use it to load the data from dump. mysqldump produces a dump file, which just contains SQL commands necessary to recreate database structure and repopulate it with data.

To restore feed the dump into mysql.exe .

When you do

mysql -u[username] -p[root_password] [database_name] < dumpfile.sql

you basically login into MySQL, then you ask it to perform all the SQL operations saved in the dumpfile.sql It's that simple.