Java runtime code when connecting to MySQL prompt: class error not found

Write code using the IntelliJ idea Community edition.

When I use the code to connect to MySQL, it appears: Java.lang.ClassNotFoundException:com.mysql.jdbc.Driver error

Then it's curious that import imports data.

Later, using the idea tool to open the previous exercise, found that the rack is also present.

But the new practice didn't get the bag in. Then there is this type of error:

The reason: When using the idea tool development, if the previous practice has added the corresponding data, then in the external libraries can be displayed, but not normal use.

Scenario: Re-add the MySQL JDK to the new exercise and rerun it to normal.

Oolong a game, the same tool run, between different exercises if you use the same jra, it is best to add two practice places

Java runtime code when connecting to MySQL prompt: class error not found