A SQL question to test your database's ability to use

Title: In the database, such as the following data, the user finally remaining amount.

User	Type	Amount
A	Deposit	100
A	Deposit	200
A	Remove	100
A	Remove	200
A	Deposit	300
A	Remove	300

I have more contact with Oracle, so give an Oracle solution:

Sum (Decode (...)) Can solve all of the above similar problems, specific I will not write, you write your own based on will be profound!

If you have a better way, please leave a message!

The best way to achieve MySQL, because the next will be using MySQL database!

A SQL question to test your database's ability to use