不带参数，直接启动，报错：
1 | Caused by: org.datanucleus.store.rdbms.connectionpool.DatastoreDriverNotFoundException: The specified datastore driver ("com.mysql.jdbc.Driver") was not found in the CLASSPATH. Please check your CLASSPATH specification, and the name of the driver. |
带参数启动成功：
1 | spark-sql --master local[2] --jars ~/lib/mysql-connector-java-5.1.47.jar --driver-class-path ~/lib/mysql-connector-java-5.1.47.jar |